[PATCH v2 0/3] media: uvcvideo: use vb2 ioctl and fop helpers

[PATCH v2 0/3] media: uvcvideo: use vb2 ioctl and fop helpers

[Ricardo Ribalda]

This is a rebump of a 4 years old patch from Hans.
https://lore.kernel.org/linux-media/20210618122923.385938-21-ribalda@chromium.org/

It brings "new" helpers to the uvcdriver and removes tons of code.

The patch:
media: uvcvideo: Refactor uvc_queue_streamon
Is already in the uvc tree. It is here just for CI purposes, do not
review.

I have uploaded my working tree at:
https://gitlab.freedesktop.org/linux-media/users/ribalda/-/commits/b4/uvc-fop
which shows the differences from the original patch, this is mainly for
helping the review to people familiar with the previous patch.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
Changes in v2, Thanks HansV:
- Fix typos
- Use start_streaming and stop_streaming for managing pm
- Link to v1: https://lore.kernel.org/r/20250522-uvc-fop-v1-0-3bfe7a00f31d@chromium.org

---
Hans Verkuil (1):
      media: uvcvideo: Use vb2 ioctl and fop helpers

Ricardo Ribalda (2):
      media: uvcvideo: Refactor uvc_queue_streamon
      media: uvcvideo: Remove stream->is_streaming field

 drivers/media/usb/uvc/uvc_driver.c   |  34 +---
 drivers/media/usb/uvc/uvc_metadata.c |   8 +-
 drivers/media/usb/uvc/uvc_queue.c    | 154 ++----------------
 drivers/media/usb/uvc/uvc_v4l2.c     | 291 ++---------------------------------
 drivers/media/usb/uvc/uvcvideo.h     |  38 +----
 5 files changed, 37 insertions(+), 488 deletions(-)
---
base-commit: 5e1ff2314797bf53636468a97719a8222deca9ae
change-id: 20250521-uvc-fop-b74e9007dd51

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>

[PATCH v2 1/3] media: uvcvideo: Refactor uvc_queue_streamon

[Ricardo Ribalda]

Do uvc_pm_get before we call uvc_queue_streamon. Although the current
code is correct, uvc_ioctl_streamon is always called after uvc_pm_get,
this change makes the code more resiliant to future changes.

This change also avoids calling streamoff, which is a rather ugly thing
to do.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_v4l2.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 668a4e9d772c6d91f045ca75e2744b3a6c69da6b..862b4e34e5b629cf324479a9bb59ebe8784ccd5d 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -853,15 +853,16 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
 	if (handle->is_streaming)
 		return 0;
 
-	ret = uvc_queue_streamon(&stream->queue, type);
+	ret = uvc_pm_get(stream->dev);
 	if (ret)
 		return ret;
 
-	ret = uvc_pm_get(stream->dev);
+	ret = uvc_queue_streamon(&stream->queue, type);
 	if (ret) {
-		uvc_queue_streamoff(&stream->queue, type);
+		uvc_pm_put(stream->dev);
 		return ret;
 	}
+
 	handle->is_streaming = true;
 
 	return 0;

-- 
2.49.0.1266.g31b7d2e469-goog

[PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Ricardo Ribalda]

From: Hans Verkuil <hans@jjverkuil.nl>

When uvc was written the vb2 ioctl and file operation helpers didn't exist.

This patch switches uvc over to those helpers, which removes a lot of
boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling and allows us
to drop the 'privileges' scheme, since that's now handled inside the vb2
helpers.

This makes it possible for uvc to fix the v4l2-compliance streaming tests:
 warn: v4l2-test-formats.cpp(1075): Could not set fmt2

This patch introduces a change on behavior on the uvcdriver to be
aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
S_FORMAT do no grant exclusive ownership of the device.

Reviewed-by: Hans de Goede <hansg@kernel.org>
Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c   |  34 +----
 drivers/media/usb/uvc/uvc_metadata.c |   8 +-
 drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
 drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
 drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
 5 files changed, 30 insertions(+), 443 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
 	INIT_LIST_HEAD(&chain->entities);
 	mutex_init(&chain->ctrl_mutex);
 	chain->dev = dev;
-	v4l2_prio_init(&chain->prio);
 
 	return chain;
 }
@@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
 		if (!video_is_registered(&stream->vdev))
 			continue;
 
-		/*
-		 * For stream->vdev we follow the same logic as:
-		 * vb2_video_unregister_device().
-		 */
-
-		/* 1. Take a reference to vdev */
-		get_device(&stream->vdev.dev);
-
-		/* 2. Ensure that no new ioctls can be called. */
-		video_unregister_device(&stream->vdev);
-
-		/* 3. Wait for old ioctls to finish. */
-		mutex_lock(&stream->mutex);
-
-		/* 4. Stop streaming. */
-		uvc_queue_release(&stream->queue);
-
-		mutex_unlock(&stream->mutex);
-
-		put_device(&stream->vdev.dev);
-
-		/*
-		 * For stream->meta.vdev we can directly call:
-		 * vb2_video_unregister_device().
-		 */
+		vb2_video_unregister_device(&stream->vdev);
 		vb2_video_unregister_device(&stream->meta.vdev);
 
 		/*
@@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
 	vdev->fops = fops;
 	vdev->ioctl_ops = ioctl_ops;
 	vdev->release = uvc_release;
-	vdev->prio = &stream->chain->prio;
+	vdev->queue = &queue->queue;
+	vdev->lock = &queue->mutex;
 	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
 		vdev->vfl_dir = VFL_DIR_TX;
 	else
@@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
 		if (stream->intf == intf) {
 			ret = uvc_video_resume(stream, reset);
 			if (ret < 0)
-				uvc_queue_streamoff(&stream->queue,
-						    stream->queue.queue.type);
+				vb2_streamoff(&stream->queue.queue,
+					      stream->queue.queue.type);
 			return ret;
 		}
 	}
diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
--- a/drivers/media/usb/uvc/uvc_metadata.c
+++ b/drivers/media/usb/uvc/uvc_metadata.c
@@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
 	 */
 	mutex_lock(&stream->mutex);
 
-	if (uvc_queue_allocated(&stream->queue))
+	if (vb2_is_busy(&stream->meta.queue.queue))
 		ret = -EBUSY;
 	else
 		stream->meta.format = fmt->dataformat;
@@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
 
 	stream->meta.format = V4L2_META_FMT_UVC;
 
-	/*
-	 * The video interface queue uses manual locking and thus does not set
-	 * the queue pointer. Set it manually here.
-	 */
-	vdev->queue = &queue->queue;
-
 	return uvc_register_video_device(dev, stream, vdev, queue,
 					 V4L2_BUF_TYPE_META_CAPTURE,
 					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
 	return 0;
 }
 
-void uvc_queue_release(struct uvc_video_queue *queue)
-{
-	mutex_lock(&queue->mutex);
-	vb2_queue_release(&queue->queue);
-	mutex_unlock(&queue->mutex);
-}
-
-/* -----------------------------------------------------------------------------
- * V4L2 queue operations
- */
-
-int uvc_request_buffers(struct uvc_video_queue *queue,
-			struct v4l2_requestbuffers *rb)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_reqbufs(&queue->queue, rb);
-	mutex_unlock(&queue->mutex);
-
-	return ret ? ret : rb->count;
-}
-
-int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_querybuf(&queue->queue, buf);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_create_buffers(struct uvc_video_queue *queue,
-		       struct v4l2_create_buffers *cb)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_create_bufs(&queue->queue, cb);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_buffer(struct uvc_video_queue *queue,
-		     struct media_device *mdev, struct v4l2_buffer *buf)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_qbuf(&queue->queue, mdev, buf);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_export_buffer(struct uvc_video_queue *queue,
-		      struct v4l2_exportbuffer *exp)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_expbuf(&queue->queue, exp);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
-		       int nonblocking)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_streamon(&queue->queue, type);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
-{
-	int ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_streamoff(&queue->queue, type);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
-int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
-{
-	return vb2_mmap(&queue->queue, vma);
-}
-
-#ifndef CONFIG_MMU
-unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
-		unsigned long pgoff)
-{
-	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
-}
-#endif
-
-__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
-			    poll_table *wait)
-{
-	__poll_t ret;
-
-	mutex_lock(&queue->mutex);
-	ret = vb2_poll(&queue->queue, file, wait);
-	mutex_unlock(&queue->mutex);
-
-	return ret;
-}
-
 /* -----------------------------------------------------------------------------
  *
  */
 
-/*
- * Check if buffers have been allocated.
- */
-int uvc_queue_allocated(struct uvc_video_queue *queue)
-{
-	int allocated;
-
-	mutex_lock(&queue->mutex);
-	allocated = vb2_is_busy(&queue->queue);
-	mutex_unlock(&queue->mutex);
-
-	return allocated;
-}
-
 /*
  * Cancel the video buffers queue.
  *
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
 	usb_autopm_put_interface(dev->intf);
 }
 
-static int uvc_acquire_privileges(struct uvc_fh *handle);
-
 static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
 				      struct uvc_control_mapping *map,
 				      const struct uvc_xu_control_mapping *xmap)
@@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
 	const struct uvc_frame *frame;
 	int ret;
 
-	ret = uvc_acquire_privileges(handle);
-	if (ret < 0)
-		return ret;
-
 	if (fmt->type != stream->type)
 		return -EINVAL;
 
@@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
 		return ret;
 
 	mutex_lock(&stream->mutex);
-
-	if (uvc_queue_allocated(&stream->queue)) {
+	if (vb2_is_busy(&stream->queue.queue)) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
 	unsigned int i;
 	int ret;
 
-	ret = uvc_acquire_privileges(handle);
-	if (ret < 0)
-		return ret;
-
 	if (parm->type != stream->type)
 		return -EINVAL;
 
@@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
 	return 0;
 }
 
-/* ------------------------------------------------------------------------
- * Privilege management
- */
-
-/*
- * Privilege management is the multiple-open implementation basis. The current
- * implementation is completely transparent for the end-user and doesn't
- * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
- * Those ioctls enable finer control on the device (by making possible for a
- * user to request exclusive access to a device), but are not mature yet.
- * Switching to the V4L2 priority mechanism might be considered in the future
- * if this situation changes.
- *
- * Each open instance of a UVC device can either be in a privileged or
- * unprivileged state. Only a single instance can be in a privileged state at
- * a given time. Trying to perform an operation that requires privileges will
- * automatically acquire the required privileges if possible, or return -EBUSY
- * otherwise. Privileges are dismissed when closing the instance or when
- * freeing the video buffers using VIDIOC_REQBUFS.
- *
- * Operations that require privileges are:
- *
- * - VIDIOC_S_INPUT
- * - VIDIOC_S_PARM
- * - VIDIOC_S_FMT
- * - VIDIOC_CREATE_BUFS
- * - VIDIOC_REQBUFS
- */
-static int uvc_acquire_privileges(struct uvc_fh *handle)
-{
-	/* Always succeed if the handle is already privileged. */
-	if (handle->state == UVC_HANDLE_ACTIVE)
-		return 0;
-
-	/* Check if the device already has a privileged handle. */
-	if (atomic_inc_return(&handle->stream->active) != 1) {
-		atomic_dec(&handle->stream->active);
-		return -EBUSY;
-	}
-
-	handle->state = UVC_HANDLE_ACTIVE;
-	return 0;
-}
-
-static void uvc_dismiss_privileges(struct uvc_fh *handle)
-{
-	if (handle->state == UVC_HANDLE_ACTIVE)
-		atomic_dec(&handle->stream->active);
-
-	handle->state = UVC_HANDLE_PASSIVE;
-}
-
-static int uvc_has_privileges(struct uvc_fh *handle)
-{
-	return handle->state == UVC_HANDLE_ACTIVE;
-}
-
 /* ------------------------------------------------------------------------
  * V4L2 file operations
  */
@@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
 	v4l2_fh_add(&handle->vfh);
 	handle->chain = stream->chain;
 	handle->stream = stream;
-	handle->state = UVC_HANDLE_PASSIVE;
 	file->private_data = handle;
 
 	return 0;
@@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
 
 	uvc_ctrl_cleanup_fh(handle);
 
-	/* Only free resources if this is a privileged handle. */
-	if (uvc_has_privileges(handle))
-		uvc_queue_release(&stream->queue);
-
 	if (handle->is_streaming)
 		uvc_pm_put(stream->dev);
 
 	/* Release the file handle. */
-	uvc_dismiss_privileges(handle);
-	v4l2_fh_del(&handle->vfh);
-	v4l2_fh_exit(&handle->vfh);
-	kfree(handle);
+	vb2_fop_release(file);
 	file->private_data = NULL;
 
 	return 0;
@@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
 	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
 }
 
-static int uvc_ioctl_reqbufs(struct file *file, void *fh,
-			     struct v4l2_requestbuffers *rb)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-	int ret;
-
-	ret = uvc_acquire_privileges(handle);
-	if (ret < 0)
-		return ret;
-
-	mutex_lock(&stream->mutex);
-	ret = uvc_request_buffers(&stream->queue, rb);
-	mutex_unlock(&stream->mutex);
-	if (ret < 0)
-		return ret;
-
-	if (ret == 0)
-		uvc_dismiss_privileges(handle);
-
-	return 0;
-}
-
-static int uvc_ioctl_querybuf(struct file *file, void *fh,
-			      struct v4l2_buffer *buf)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	return uvc_query_buffer(&stream->queue, buf);
-}
-
-static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	return uvc_queue_buffer(&stream->queue,
-				stream->vdev.v4l2_dev->mdev, buf);
-}
-
-static int uvc_ioctl_expbuf(struct file *file, void *fh,
-			    struct v4l2_exportbuffer *exp)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	return uvc_export_buffer(&stream->queue, exp);
-}
-
-static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	return uvc_dequeue_buffer(&stream->queue, buf,
-				  file->f_flags & O_NONBLOCK);
-}
-
-static int uvc_ioctl_create_bufs(struct file *file, void *fh,
-				  struct v4l2_create_buffers *cb)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-	int ret;
-
-	ret = uvc_acquire_privileges(handle);
-	if (ret < 0)
-		return ret;
-
-	return uvc_create_buffers(&stream->queue, cb);
-}
-
 static int uvc_ioctl_streamon(struct file *file, void *fh,
 			      enum v4l2_buf_type type)
 {
@@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
 	struct uvc_streaming *stream = handle->stream;
 	int ret;
 
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	guard(mutex)(&stream->mutex);
-
 	if (handle->is_streaming)
 		return 0;
 
@@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
 	if (ret)
 		return ret;
 
-	ret = uvc_queue_streamon(&stream->queue, type);
+	ret = vb2_ioctl_streamon(file, fh, type);
 	if (ret) {
 		uvc_pm_put(stream->dev);
 		return ret;
@@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
 {
 	struct uvc_fh *handle = fh;
 	struct uvc_streaming *stream = handle->stream;
+	int ret;
 
-	if (!uvc_has_privileges(handle))
-		return -EBUSY;
-
-	guard(mutex)(&stream->mutex);
+	ret = vb2_ioctl_streamoff(file, fh, type);
+	if (ret)
+		return ret;
 
-	uvc_queue_streamoff(&stream->queue, type);
 	if (handle->is_streaming) {
 		handle->is_streaming = false;
 		uvc_pm_put(stream->dev);
@@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
 static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
 {
 	struct uvc_fh *handle = fh;
+	struct uvc_streaming *stream = handle->stream;
 	struct uvc_video_chain *chain = handle->chain;
 	u8 *buf;
 	int ret;
 
-	ret = uvc_acquire_privileges(handle);
-	if (ret < 0)
-		return ret;
+	if (vb2_is_busy(&stream->queue.queue))
+		return -EBUSY;
 
 	if (chain->selector == NULL ||
 	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
@@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
 	return ret;
 }
 
-static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
-		    size_t count, loff_t *ppos)
-{
-	struct uvc_fh *handle = file->private_data;
-	struct uvc_streaming *stream = handle->stream;
-
-	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
-	return -EINVAL;
-}
-
-static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	struct uvc_fh *handle = file->private_data;
-	struct uvc_streaming *stream = handle->stream;
-
-	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
-
-	return uvc_queue_mmap(&stream->queue, vma);
-}
-
-static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
-{
-	struct uvc_fh *handle = file->private_data;
-	struct uvc_streaming *stream = handle->stream;
-
-	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
-
-	return uvc_queue_poll(&stream->queue, file, wait);
-}
-
-#ifndef CONFIG_MMU
-static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
-		unsigned long addr, unsigned long len, unsigned long pgoff,
-		unsigned long flags)
-{
-	struct uvc_fh *handle = file->private_data;
-	struct uvc_streaming *stream = handle->stream;
-
-	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
-
-	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
-}
-#endif
-
 const struct v4l2_ioctl_ops uvc_ioctl_ops = {
 	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
 	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
@@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
 	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
 	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
 	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
-	.vidioc_reqbufs = uvc_ioctl_reqbufs,
-	.vidioc_querybuf = uvc_ioctl_querybuf,
-	.vidioc_qbuf = uvc_ioctl_qbuf,
-	.vidioc_expbuf = uvc_ioctl_expbuf,
-	.vidioc_dqbuf = uvc_ioctl_dqbuf,
-	.vidioc_create_bufs = uvc_ioctl_create_bufs,
+	.vidioc_reqbufs = vb2_ioctl_reqbufs,
+	.vidioc_querybuf = vb2_ioctl_querybuf,
+	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
+	.vidioc_qbuf = vb2_ioctl_qbuf,
+	.vidioc_expbuf = vb2_ioctl_expbuf,
+	.vidioc_dqbuf = vb2_ioctl_dqbuf,
+	.vidioc_create_bufs = vb2_ioctl_create_bufs,
 	.vidioc_streamon = uvc_ioctl_streamon,
 	.vidioc_streamoff = uvc_ioctl_streamoff,
 	.vidioc_enum_input = uvc_ioctl_enum_input,
@@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
 #endif
-	.read		= uvc_v4l2_read,
-	.mmap		= uvc_v4l2_mmap,
-	.poll		= uvc_v4l2_poll,
+	.mmap		= vb2_fop_mmap,
+	.poll		= vb2_fop_poll,
 #ifndef CONFIG_MMU
-	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
+	.get_unmapped_area = vb2_fop_get_unmapped_area,
 #endif
 };
 
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -326,7 +326,10 @@ struct uvc_buffer {
 
 struct uvc_video_queue {
 	struct vb2_queue queue;
-	struct mutex mutex;			/* Protects queue */
+	struct mutex mutex;			/*
+						 * Serializes vb2_queue and
+						 * fops
+						 */
 
 	unsigned int flags;
 	unsigned int buf_used;
@@ -349,7 +352,6 @@ struct uvc_video_chain {
 						 * uvc_fh.pending_async_ctrls
 						 */
 
-	struct v4l2_prio_state prio;		/* V4L2 priority state */
 	u32 caps;				/* V4L2 chain-wide caps */
 	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
 };
@@ -619,16 +621,10 @@ struct uvc_device {
 	struct uvc_entity *gpio_unit;
 };
 
-enum uvc_handle_state {
-	UVC_HANDLE_PASSIVE	= 0,
-	UVC_HANDLE_ACTIVE	= 1,
-};
-
 struct uvc_fh {
 	struct v4l2_fh vfh;
 	struct uvc_video_chain *chain;
 	struct uvc_streaming *stream;
-	enum uvc_handle_state state;
 	unsigned int pending_async_ctrls;
 	bool is_streaming;
 };
@@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
 
 /* Video buffers queue management. */
 int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
-void uvc_queue_release(struct uvc_video_queue *queue);
-int uvc_request_buffers(struct uvc_video_queue *queue,
-			struct v4l2_requestbuffers *rb);
-int uvc_query_buffer(struct uvc_video_queue *queue,
-		     struct v4l2_buffer *v4l2_buf);
-int uvc_create_buffers(struct uvc_video_queue *queue,
-		       struct v4l2_create_buffers *v4l2_cb);
-int uvc_queue_buffer(struct uvc_video_queue *queue,
-		     struct media_device *mdev,
-		     struct v4l2_buffer *v4l2_buf);
-int uvc_export_buffer(struct uvc_video_queue *queue,
-		      struct v4l2_exportbuffer *exp);
-int uvc_dequeue_buffer(struct uvc_video_queue *queue,
-		       struct v4l2_buffer *v4l2_buf, int nonblocking);
-int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
-int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
 void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
 struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
 					 struct uvc_buffer *buf);
 struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
 void uvc_queue_buffer_release(struct uvc_buffer *buf);
-int uvc_queue_mmap(struct uvc_video_queue *queue,
-		   struct vm_area_struct *vma);
-__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
-			poll_table *wait);
-#ifndef CONFIG_MMU
-unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
-					  unsigned long pgoff);
-#endif
-int uvc_queue_allocated(struct uvc_video_queue *queue);
 static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
 {
 	return vb2_is_streaming(&queue->queue);

-- 
2.49.0.1266.g31b7d2e469-goog

[PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Ricardo Ribalda]

The is_streaming field is used by modular PM to know if the device is
currently streaming or not.

With the transition to vb2 and fop helpers, we can use vb2 functions for
the same functionality. The great benefit is that vb2 already takes
track of the streaming state for us.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_queue.c | 11 ++++++++-
 drivers/media/usb/uvc/uvc_v4l2.c  | 51 ++-------------------------------------
 drivers/media/usb/uvc/uvcvideo.h  |  1 -
 3 files changed, 12 insertions(+), 51 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 72c5494dee9f46ff61072e7d293bfaddda40e615..dff93bec204428b8aebc09332e0322fa68823fa4 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -165,12 +165,18 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	lockdep_assert_irqs_enabled();
 
+	ret = uvc_pm_get(stream->dev);
+	if (ret)
+		return ret;
+
 	queue->buf_used = 0;
 
 	ret = uvc_video_start_streaming(stream);
 	if (ret == 0)
 		return 0;
 
+	uvc_pm_put(stream->dev);
+
 	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
 	spin_unlock_irq(&queue->irqlock);
@@ -181,11 +187,14 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 static void uvc_stop_streaming(struct vb2_queue *vq)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
+	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
 
 	lockdep_assert_irqs_enabled();
 
-	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
+	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
+		uvc_pm_put(stream->dev);
 		uvc_video_stop_streaming(uvc_queue_to_stream(queue));
+	}
 
 	spin_lock_irq(&queue->irqlock);
 	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 7a5ecbefa32c0a6b74c85d7f77a25b433598471e..d4bee0d4334b764c0cf02363b573b55fb44eb228 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -617,9 +617,6 @@ static int uvc_v4l2_release(struct file *file)
 
 	uvc_ctrl_cleanup_fh(handle);
 
-	if (handle->is_streaming)
-		uvc_pm_put(stream->dev);
-
 	/* Release the file handle. */
 	vb2_fop_release(file);
 	file->private_data = NULL;
@@ -677,50 +674,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
 	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
 }
 
-static int uvc_ioctl_streamon(struct file *file, void *fh,
-			      enum v4l2_buf_type type)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-	int ret;
-
-	if (handle->is_streaming)
-		return 0;
-
-	ret = uvc_pm_get(stream->dev);
-	if (ret)
-		return ret;
-
-	ret = vb2_ioctl_streamon(file, fh, type);
-	if (ret) {
-		uvc_pm_put(stream->dev);
-		return ret;
-	}
-
-	handle->is_streaming = true;
-
-	return 0;
-}
-
-static int uvc_ioctl_streamoff(struct file *file, void *fh,
-			       enum v4l2_buf_type type)
-{
-	struct uvc_fh *handle = fh;
-	struct uvc_streaming *stream = handle->stream;
-	int ret;
-
-	ret = vb2_ioctl_streamoff(file, fh, type);
-	if (ret)
-		return ret;
-
-	if (handle->is_streaming) {
-		handle->is_streaming = false;
-		uvc_pm_put(stream->dev);
-	}
-
-	return 0;
-}
-
 static int uvc_ioctl_enum_input(struct file *file, void *fh,
 				struct v4l2_input *input)
 {
@@ -1323,8 +1276,8 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
 	.vidioc_expbuf = vb2_ioctl_expbuf,
 	.vidioc_dqbuf = vb2_ioctl_dqbuf,
 	.vidioc_create_bufs = vb2_ioctl_create_bufs,
-	.vidioc_streamon = uvc_ioctl_streamon,
-	.vidioc_streamoff = uvc_ioctl_streamoff,
+	.vidioc_streamon = vb2_ioctl_streamon,
+	.vidioc_streamoff = vb2_ioctl_streamoff,
 	.vidioc_enum_input = uvc_ioctl_enum_input,
 	.vidioc_g_input = uvc_ioctl_g_input,
 	.vidioc_s_input = uvc_ioctl_s_input,
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 3ddbf065a2cbae40ee48cb06f84ca8f0052990c4..f895f690f7cdc1af942d5f3a5f10e9dd1c956a35 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -626,7 +626,6 @@ struct uvc_fh {
 	struct uvc_video_chain *chain;
 	struct uvc_streaming *stream;
 	unsigned int pending_async_ctrls;
-	bool is_streaming;
 };
 
 /* ------------------------------------------------------------------------

-- 
2.49.0.1266.g31b7d2e469-goog

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Hans Verkuil]

On 02/06/2025 14:59, Ricardo Ribalda wrote:
> The is_streaming field is used by modular PM to know if the device is
> currently streaming or not.
> 
> With the transition to vb2 and fop helpers, we can use vb2 functions for
> the same functionality. The great benefit is that vb2 already takes
> track of the streaming state for us.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_queue.c | 11 ++++++++-
>  drivers/media/usb/uvc/uvc_v4l2.c  | 51 ++-------------------------------------
>  drivers/media/usb/uvc/uvcvideo.h  |  1 -
>  3 files changed, 12 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> index 72c5494dee9f46ff61072e7d293bfaddda40e615..dff93bec204428b8aebc09332e0322fa68823fa4 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -165,12 +165,18 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
>  
>  	lockdep_assert_irqs_enabled();
>  
> +	ret = uvc_pm_get(stream->dev);
> +	if (ret)
> +		return ret;
> +
>  	queue->buf_used = 0;
>  
>  	ret = uvc_video_start_streaming(stream);

I'm not sure this is correct. See comments below.

>  	if (ret == 0)
>  		return 0;
>  
> +	uvc_pm_put(stream->dev);
> +
>  	spin_lock_irq(&queue->irqlock);
>  	uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
>  	spin_unlock_irq(&queue->irqlock);
> @@ -181,11 +187,14 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
>  static void uvc_stop_streaming(struct vb2_queue *vq)
>  {
>  	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> +	struct uvc_streaming *stream = uvc_queue_to_stream(queue);
>  
>  	lockdep_assert_irqs_enabled();
>  
> -	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
> +	if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
> +		uvc_pm_put(stream->dev);

This doesn't look right, for both video and metadata uvc_pm_get is called,
but only for video is put called.

>  		uvc_video_stop_streaming(uvc_queue_to_stream(queue));

And this is odd too.

> +	}

My assumption is that uvc_video_start_streaming and uvc_video_stop_streaming
are valid for both video and meta: i.e. the first time you start streaming
(either video or meta) you call uvc_video_start_streaming. If you were already
streaming for e.g. video, then start streaming metadata (or vice versa), then
you don't need to do anything in start_streaming.

Same for stop_streaming: only if both video and metadata stopped streaming
is uvc_video_stop_streaming called.

Please correct me if I am wrong.

In any case, if I am right, then you have to rework this code accordingly.

Regardless, you need to test various sequences of streaming video and metadata
in different orders and make sure this is handled correctly.

Regards,

	Hans

>  
>  	spin_lock_irq(&queue->irqlock);
>  	uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 7a5ecbefa32c0a6b74c85d7f77a25b433598471e..d4bee0d4334b764c0cf02363b573b55fb44eb228 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -617,9 +617,6 @@ static int uvc_v4l2_release(struct file *file)
>  
>  	uvc_ctrl_cleanup_fh(handle);
>  
> -	if (handle->is_streaming)
> -		uvc_pm_put(stream->dev);
> -
>  	/* Release the file handle. */
>  	vb2_fop_release(file);
>  	file->private_data = NULL;
> @@ -677,50 +674,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>  }
>  
> -static int uvc_ioctl_streamon(struct file *file, void *fh,
> -			      enum v4l2_buf_type type)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -	int ret;
> -
> -	if (handle->is_streaming)
> -		return 0;
> -
> -	ret = uvc_pm_get(stream->dev);
> -	if (ret)
> -		return ret;
> -
> -	ret = vb2_ioctl_streamon(file, fh, type);
> -	if (ret) {
> -		uvc_pm_put(stream->dev);
> -		return ret;
> -	}
> -
> -	handle->is_streaming = true;
> -
> -	return 0;
> -}
> -
> -static int uvc_ioctl_streamoff(struct file *file, void *fh,
> -			       enum v4l2_buf_type type)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -	int ret;
> -
> -	ret = vb2_ioctl_streamoff(file, fh, type);
> -	if (ret)
> -		return ret;
> -
> -	if (handle->is_streaming) {
> -		handle->is_streaming = false;
> -		uvc_pm_put(stream->dev);
> -	}
> -
> -	return 0;
> -}
> -
>  static int uvc_ioctl_enum_input(struct file *file, void *fh,
>  				struct v4l2_input *input)
>  {
> @@ -1323,8 +1276,8 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>  	.vidioc_expbuf = vb2_ioctl_expbuf,
>  	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>  	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> -	.vidioc_streamon = uvc_ioctl_streamon,
> -	.vidioc_streamoff = uvc_ioctl_streamoff,
> +	.vidioc_streamon = vb2_ioctl_streamon,
> +	.vidioc_streamoff = vb2_ioctl_streamoff,
>  	.vidioc_enum_input = uvc_ioctl_enum_input,
>  	.vidioc_g_input = uvc_ioctl_g_input,
>  	.vidioc_s_input = uvc_ioctl_s_input,
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 3ddbf065a2cbae40ee48cb06f84ca8f0052990c4..f895f690f7cdc1af942d5f3a5f10e9dd1c956a35 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -626,7 +626,6 @@ struct uvc_fh {
>  	struct uvc_video_chain *chain;
>  	struct uvc_streaming *stream;
>  	unsigned int pending_async_ctrls;
> -	bool is_streaming;
>  };
>  
>  /* ------------------------------------------------------------------------
> 

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Ricardo Ribalda]

Hi Hans

On Mon, 2 Jun 2025 at 15:23, Hans Verkuil <hans@jjverkuil.nl> wrote:
>
> On 02/06/2025 14:59, Ricardo Ribalda wrote:
> > The is_streaming field is used by modular PM to know if the device is
> > currently streaming or not.
> >
> > With the transition to vb2 and fop helpers, we can use vb2 functions for
> > the same functionality. The great benefit is that vb2 already takes
> > track of the streaming state for us.
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_queue.c | 11 ++++++++-
> >  drivers/media/usb/uvc/uvc_v4l2.c  | 51 ++-------------------------------------
> >  drivers/media/usb/uvc/uvcvideo.h  |  1 -
> >  3 files changed, 12 insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > index 72c5494dee9f46ff61072e7d293bfaddda40e615..dff93bec204428b8aebc09332e0322fa68823fa4 100644
> > --- a/drivers/media/usb/uvc/uvc_queue.c
> > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > @@ -165,12 +165,18 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >
> >       lockdep_assert_irqs_enabled();
> >
> > +     ret = uvc_pm_get(stream->dev);
> > +     if (ret)
> > +             return ret;
> > +
> >       queue->buf_used = 0;
> >
> >       ret = uvc_video_start_streaming(stream);
>
> I'm not sure this is correct. See comments below.
>
> >       if (ret == 0)
> >               return 0;
> >
> > +     uvc_pm_put(stream->dev);
> > +
> >       spin_lock_irq(&queue->irqlock);
> >       uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
> >       spin_unlock_irq(&queue->irqlock);
> > @@ -181,11 +187,14 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >  static void uvc_stop_streaming(struct vb2_queue *vq)
> >  {
> >       struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> > +     struct uvc_streaming *stream = uvc_queue_to_stream(queue);
> >
> >       lockdep_assert_irqs_enabled();
> >
> > -     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
> > +     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
> > +             uvc_pm_put(stream->dev);
>
> This doesn't look right, for both video and metadata uvc_pm_get is called,
> but only for video is put called.

Please take a look at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/usb/uvc/uvc_queue.c#n195

start_streaming is not called for metadata nodes, only for video nodes.



>
> >               uvc_video_stop_streaming(uvc_queue_to_stream(queue));
>
> And this is odd too.
>
> > +     }
>
> My assumption is that uvc_video_start_streaming and uvc_video_stop_streaming
> are valid for both video and meta: i.e. the first time you start streaming
> (either video or meta) you call uvc_video_start_streaming. If you were already
> streaming for e.g. video, then start streaming metadata (or vice versa), then
> you don't need to do anything in start_streaming.
>
> Same for stop_streaming: only if both video and metadata stopped streaming
> is uvc_video_stop_streaming called.
>
> Please correct me if I am wrong.
>
> In any case, if I am right, then you have to rework this code accordingly.
>
> Regardless, you need to test various sequences of streaming video and metadata
> in different orders and make sure this is handled correctly.

I have tried streaming and getting frames. After some seconds the
device turns off as expected.

>
> Regards,
>
>         Hans
>
> >
> >       spin_lock_irq(&queue->irqlock);
> >       uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > index 7a5ecbefa32c0a6b74c85d7f77a25b433598471e..d4bee0d4334b764c0cf02363b573b55fb44eb228 100644
> > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > @@ -617,9 +617,6 @@ static int uvc_v4l2_release(struct file *file)
> >
> >       uvc_ctrl_cleanup_fh(handle);
> >
> > -     if (handle->is_streaming)
> > -             uvc_pm_put(stream->dev);
> > -
> >       /* Release the file handle. */
> >       vb2_fop_release(file);
> >       file->private_data = NULL;
> > @@ -677,50 +674,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> >       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> >  }
> >
> > -static int uvc_ioctl_streamon(struct file *file, void *fh,
> > -                           enum v4l2_buf_type type)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -     int ret;
> > -
> > -     if (handle->is_streaming)
> > -             return 0;
> > -
> > -     ret = uvc_pm_get(stream->dev);
> > -     if (ret)
> > -             return ret;
> > -
> > -     ret = vb2_ioctl_streamon(file, fh, type);
> > -     if (ret) {
> > -             uvc_pm_put(stream->dev);
> > -             return ret;
> > -     }
> > -
> > -     handle->is_streaming = true;
> > -
> > -     return 0;
> > -}
> > -
> > -static int uvc_ioctl_streamoff(struct file *file, void *fh,
> > -                            enum v4l2_buf_type type)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -     int ret;
> > -
> > -     ret = vb2_ioctl_streamoff(file, fh, type);
> > -     if (ret)
> > -             return ret;
> > -
> > -     if (handle->is_streaming) {
> > -             handle->is_streaming = false;
> > -             uvc_pm_put(stream->dev);
> > -     }
> > -
> > -     return 0;
> > -}
> > -
> >  static int uvc_ioctl_enum_input(struct file *file, void *fh,
> >                               struct v4l2_input *input)
> >  {
> > @@ -1323,8 +1276,8 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >       .vidioc_expbuf = vb2_ioctl_expbuf,
> >       .vidioc_dqbuf = vb2_ioctl_dqbuf,
> >       .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > -     .vidioc_streamon = uvc_ioctl_streamon,
> > -     .vidioc_streamoff = uvc_ioctl_streamoff,
> > +     .vidioc_streamon = vb2_ioctl_streamon,
> > +     .vidioc_streamoff = vb2_ioctl_streamoff,
> >       .vidioc_enum_input = uvc_ioctl_enum_input,
> >       .vidioc_g_input = uvc_ioctl_g_input,
> >       .vidioc_s_input = uvc_ioctl_s_input,
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index 3ddbf065a2cbae40ee48cb06f84ca8f0052990c4..f895f690f7cdc1af942d5f3a5f10e9dd1c956a35 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -626,7 +626,6 @@ struct uvc_fh {
> >       struct uvc_video_chain *chain;
> >       struct uvc_streaming *stream;
> >       unsigned int pending_async_ctrls;
> > -     bool is_streaming;
> >  };
> >
> >  /* ------------------------------------------------------------------------
> >
>


-- 
Ricardo Ribalda

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Hans Verkuil]

On 02/06/2025 15:33, Ricardo Ribalda wrote:
> Hi Hans
> 
> On Mon, 2 Jun 2025 at 15:23, Hans Verkuil <hans@jjverkuil.nl> wrote:
>>
>> On 02/06/2025 14:59, Ricardo Ribalda wrote:
>>> The is_streaming field is used by modular PM to know if the device is
>>> currently streaming or not.
>>>
>>> With the transition to vb2 and fop helpers, we can use vb2 functions for
>>> the same functionality. The great benefit is that vb2 already takes
>>> track of the streaming state for us.
>>>
>>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>>> ---
>>>  drivers/media/usb/uvc/uvc_queue.c | 11 ++++++++-
>>>  drivers/media/usb/uvc/uvc_v4l2.c  | 51 ++-------------------------------------
>>>  drivers/media/usb/uvc/uvcvideo.h  |  1 -
>>>  3 files changed, 12 insertions(+), 51 deletions(-)
>>>
>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
>>> index 72c5494dee9f46ff61072e7d293bfaddda40e615..dff93bec204428b8aebc09332e0322fa68823fa4 100644
>>> --- a/drivers/media/usb/uvc/uvc_queue.c
>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
>>> @@ -165,12 +165,18 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
>>>
>>>       lockdep_assert_irqs_enabled();
>>>
>>> +     ret = uvc_pm_get(stream->dev);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>>       queue->buf_used = 0;
>>>
>>>       ret = uvc_video_start_streaming(stream);
>>
>> I'm not sure this is correct. See comments below.
>>
>>>       if (ret == 0)
>>>               return 0;
>>>
>>> +     uvc_pm_put(stream->dev);
>>> +
>>>       spin_lock_irq(&queue->irqlock);
>>>       uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
>>>       spin_unlock_irq(&queue->irqlock);
>>> @@ -181,11 +187,14 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
>>>  static void uvc_stop_streaming(struct vb2_queue *vq)
>>>  {
>>>       struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
>>> +     struct uvc_streaming *stream = uvc_queue_to_stream(queue);
>>>
>>>       lockdep_assert_irqs_enabled();
>>>
>>> -     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
>>> +     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
>>> +             uvc_pm_put(stream->dev);
>>
>> This doesn't look right, for both video and metadata uvc_pm_get is called,
>> but only for video is put called.
> 
> Please take a look at
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/usb/uvc/uvc_queue.c#n195
> 
> start_streaming is not called for metadata nodes, only for video nodes.

So when you start streaming metadata and no video is streaming, then nothing
happens. I noticed this before, in fact. Only after you also start to stream
video will the metadata start to arrive. And it stops again as soon as you
stop streaming video.

That's not really how it is supposed to work: whoever starts streaming first
is the one that calls uvc_video_start_streaming. And only when nobody is streaming
should uvc_video_stop_streaming be called. That's how it works in other drivers
(e.g. those that stream both video and vbi, or even more different types of data).

Fixing this would change the behavior of uvc, and I'm not sure if this is
something we want. I leave that to Laurent and Hans.

If this isn't fixed, then at least add a comment explaining why you test for
!= V4L2_BUF_TYPE_META_CAPTURE before calling uvc_pm_put. It's not obvious.

Regards,

	Hans

> 
> 
> 
>>
>>>               uvc_video_stop_streaming(uvc_queue_to_stream(queue));
>>
>> And this is odd too.
>>
>>> +     }
>>
>> My assumption is that uvc_video_start_streaming and uvc_video_stop_streaming
>> are valid for both video and meta: i.e. the first time you start streaming
>> (either video or meta) you call uvc_video_start_streaming. If you were already
>> streaming for e.g. video, then start streaming metadata (or vice versa), then
>> you don't need to do anything in start_streaming.
>>
>> Same for stop_streaming: only if both video and metadata stopped streaming
>> is uvc_video_stop_streaming called.
>>
>> Please correct me if I am wrong.
>>
>> In any case, if I am right, then you have to rework this code accordingly.
>>
>> Regardless, you need to test various sequences of streaming video and metadata
>> in different orders and make sure this is handled correctly.
> 
> I have tried streaming and getting frames. After some seconds the
> device turns off as expected.
> 
>>
>> Regards,
>>
>>         Hans
>>
>>>
>>>       spin_lock_irq(&queue->irqlock);
>>>       uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
>>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
>>> index 7a5ecbefa32c0a6b74c85d7f77a25b433598471e..d4bee0d4334b764c0cf02363b573b55fb44eb228 100644
>>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>>> @@ -617,9 +617,6 @@ static int uvc_v4l2_release(struct file *file)
>>>
>>>       uvc_ctrl_cleanup_fh(handle);
>>>
>>> -     if (handle->is_streaming)
>>> -             uvc_pm_put(stream->dev);
>>> -
>>>       /* Release the file handle. */
>>>       vb2_fop_release(file);
>>>       file->private_data = NULL;
>>> @@ -677,50 +674,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>>>       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>>>  }
>>>
>>> -static int uvc_ioctl_streamon(struct file *file, void *fh,
>>> -                           enum v4l2_buf_type type)
>>> -{
>>> -     struct uvc_fh *handle = fh;
>>> -     struct uvc_streaming *stream = handle->stream;
>>> -     int ret;
>>> -
>>> -     if (handle->is_streaming)
>>> -             return 0;
>>> -
>>> -     ret = uvc_pm_get(stream->dev);
>>> -     if (ret)
>>> -             return ret;
>>> -
>>> -     ret = vb2_ioctl_streamon(file, fh, type);
>>> -     if (ret) {
>>> -             uvc_pm_put(stream->dev);
>>> -             return ret;
>>> -     }
>>> -
>>> -     handle->is_streaming = true;
>>> -
>>> -     return 0;
>>> -}
>>> -
>>> -static int uvc_ioctl_streamoff(struct file *file, void *fh,
>>> -                            enum v4l2_buf_type type)
>>> -{
>>> -     struct uvc_fh *handle = fh;
>>> -     struct uvc_streaming *stream = handle->stream;
>>> -     int ret;
>>> -
>>> -     ret = vb2_ioctl_streamoff(file, fh, type);
>>> -     if (ret)
>>> -             return ret;
>>> -
>>> -     if (handle->is_streaming) {
>>> -             handle->is_streaming = false;
>>> -             uvc_pm_put(stream->dev);
>>> -     }
>>> -
>>> -     return 0;
>>> -}
>>> -
>>>  static int uvc_ioctl_enum_input(struct file *file, void *fh,
>>>                               struct v4l2_input *input)
>>>  {
>>> @@ -1323,8 +1276,8 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>       .vidioc_expbuf = vb2_ioctl_expbuf,
>>>       .vidioc_dqbuf = vb2_ioctl_dqbuf,
>>>       .vidioc_create_bufs = vb2_ioctl_create_bufs,
>>> -     .vidioc_streamon = uvc_ioctl_streamon,
>>> -     .vidioc_streamoff = uvc_ioctl_streamoff,
>>> +     .vidioc_streamon = vb2_ioctl_streamon,
>>> +     .vidioc_streamoff = vb2_ioctl_streamoff,
>>>       .vidioc_enum_input = uvc_ioctl_enum_input,
>>>       .vidioc_g_input = uvc_ioctl_g_input,
>>>       .vidioc_s_input = uvc_ioctl_s_input,
>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
>>> index 3ddbf065a2cbae40ee48cb06f84ca8f0052990c4..f895f690f7cdc1af942d5f3a5f10e9dd1c956a35 100644
>>> --- a/drivers/media/usb/uvc/uvcvideo.h
>>> +++ b/drivers/media/usb/uvc/uvcvideo.h
>>> @@ -626,7 +626,6 @@ struct uvc_fh {
>>>       struct uvc_video_chain *chain;
>>>       struct uvc_streaming *stream;
>>>       unsigned int pending_async_ctrls;
>>> -     bool is_streaming;
>>>  };
>>>
>>>  /* ------------------------------------------------------------------------
>>>
>>
> 
> 

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Laurent Pinchart]

On Mon, Jun 02, 2025 at 03:47:50PM +0200, Hans Verkuil wrote:
> On 02/06/2025 15:33, Ricardo Ribalda wrote:
> > On Mon, 2 Jun 2025 at 15:23, Hans Verkuil wrote:
> >> On 02/06/2025 14:59, Ricardo Ribalda wrote:
> >>> The is_streaming field is used by modular PM to know if the device is
> >>> currently streaming or not.
> >>>
> >>> With the transition to vb2 and fop helpers, we can use vb2 functions for
> >>> the same functionality. The great benefit is that vb2 already takes
> >>> track of the streaming state for us.
> >>>
> >>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> >>> ---
> >>>  drivers/media/usb/uvc/uvc_queue.c | 11 ++++++++-
> >>>  drivers/media/usb/uvc/uvc_v4l2.c  | 51 ++-------------------------------------
> >>>  drivers/media/usb/uvc/uvcvideo.h  |  1 -
> >>>  3 files changed, 12 insertions(+), 51 deletions(-)
> >>>
> >>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> >>> index 72c5494dee9f46ff61072e7d293bfaddda40e615..dff93bec204428b8aebc09332e0322fa68823fa4 100644
> >>> --- a/drivers/media/usb/uvc/uvc_queue.c
> >>> +++ b/drivers/media/usb/uvc/uvc_queue.c
> >>> @@ -165,12 +165,18 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >>>
> >>>       lockdep_assert_irqs_enabled();
> >>>
> >>> +     ret = uvc_pm_get(stream->dev);
> >>> +     if (ret)
> >>> +             return ret;
> >>> +
> >>>       queue->buf_used = 0;
> >>>
> >>>       ret = uvc_video_start_streaming(stream);
> >>
> >> I'm not sure this is correct. See comments below.
> >>
> >>>       if (ret == 0)
> >>>               return 0;
> >>>
> >>> +     uvc_pm_put(stream->dev);
> >>> +
> >>>       spin_lock_irq(&queue->irqlock);
> >>>       uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
> >>>       spin_unlock_irq(&queue->irqlock);
> >>> @@ -181,11 +187,14 @@ static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> >>>  static void uvc_stop_streaming(struct vb2_queue *vq)
> >>>  {
> >>>       struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> >>> +     struct uvc_streaming *stream = uvc_queue_to_stream(queue);
> >>>
> >>>       lockdep_assert_irqs_enabled();
> >>>
> >>> -     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
> >>> +     if (vq->type != V4L2_BUF_TYPE_META_CAPTURE) {
> >>> +             uvc_pm_put(stream->dev);
> >>
> >> This doesn't look right, for both video and metadata uvc_pm_get is called,
> >> but only for video is put called.
> > 
> > Please take a look at
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/media/usb/uvc/uvc_queue.c#n195
> > 
> > start_streaming is not called for metadata nodes, only for video nodes.
> 
> So when you start streaming metadata and no video is streaming, then nothing
> happens. I noticed this before, in fact. Only after you also start to stream
> video will the metadata start to arrive. And it stops again as soon as you
> stop streaming video.
> 
> That's not really how it is supposed to work: whoever starts streaming first
> is the one that calls uvc_video_start_streaming. And only when nobody is streaming
> should uvc_video_stop_streaming be called. That's how it works in other drivers
> (e.g. those that stream both video and vbi, or even more different types of data).
> 
> Fixing this would change the behavior of uvc, and I'm not sure if this is
> something we want. I leave that to Laurent and Hans.

I don't see a use case for capturing metadata only, so I think we can
keep the behaviour as-is.

> If this isn't fixed, then at least add a comment explaining why you test for
> != V4L2_BUF_TYPE_META_CAPTURE before calling uvc_pm_put. It's not obvious.

Agreed.

> >>>               uvc_video_stop_streaming(uvc_queue_to_stream(queue));
> >>
> >> And this is odd too.
> >>
> >>> +     }
> >>
> >> My assumption is that uvc_video_start_streaming and uvc_video_stop_streaming
> >> are valid for both video and meta: i.e. the first time you start streaming
> >> (either video or meta) you call uvc_video_start_streaming. If you were already
> >> streaming for e.g. video, then start streaming metadata (or vice versa), then
> >> you don't need to do anything in start_streaming.
> >>
> >> Same for stop_streaming: only if both video and metadata stopped streaming
> >> is uvc_video_stop_streaming called.
> >>
> >> Please correct me if I am wrong.
> >>
> >> In any case, if I am right, then you have to rework this code accordingly.
> >>
> >> Regardless, you need to test various sequences of streaming video and metadata
> >> in different orders and make sure this is handled correctly.
> > 
> > I have tried streaming and getting frames. After some seconds the
> > device turns off as expected.
> > 
> >>>       spin_lock_irq(&queue->irqlock);
> >>>       uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> >>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> >>> index 7a5ecbefa32c0a6b74c85d7f77a25b433598471e..d4bee0d4334b764c0cf02363b573b55fb44eb228 100644
> >>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> >>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> >>> @@ -617,9 +617,6 @@ static int uvc_v4l2_release(struct file *file)
> >>>
> >>>       uvc_ctrl_cleanup_fh(handle);
> >>>
> >>> -     if (handle->is_streaming)
> >>> -             uvc_pm_put(stream->dev);
> >>> -
> >>>       /* Release the file handle. */
> >>>       vb2_fop_release(file);
> >>>       file->private_data = NULL;
> >>> @@ -677,50 +674,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> >>>       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> >>>  }
> >>>
> >>> -static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>> -                           enum v4l2_buf_type type)
> >>> -{
> >>> -     struct uvc_fh *handle = fh;
> >>> -     struct uvc_streaming *stream = handle->stream;
> >>> -     int ret;
> >>> -
> >>> -     if (handle->is_streaming)
> >>> -             return 0;
> >>> -
> >>> -     ret = uvc_pm_get(stream->dev);
> >>> -     if (ret)
> >>> -             return ret;
> >>> -
> >>> -     ret = vb2_ioctl_streamon(file, fh, type);
> >>> -     if (ret) {
> >>> -             uvc_pm_put(stream->dev);
> >>> -             return ret;
> >>> -     }
> >>> -
> >>> -     handle->is_streaming = true;
> >>> -
> >>> -     return 0;
> >>> -}
> >>> -
> >>> -static int uvc_ioctl_streamoff(struct file *file, void *fh,
> >>> -                            enum v4l2_buf_type type)
> >>> -{
> >>> -     struct uvc_fh *handle = fh;
> >>> -     struct uvc_streaming *stream = handle->stream;
> >>> -     int ret;
> >>> -
> >>> -     ret = vb2_ioctl_streamoff(file, fh, type);
> >>> -     if (ret)
> >>> -             return ret;
> >>> -
> >>> -     if (handle->is_streaming) {
> >>> -             handle->is_streaming = false;
> >>> -             uvc_pm_put(stream->dev);
> >>> -     }
> >>> -
> >>> -     return 0;
> >>> -}
> >>> -
> >>>  static int uvc_ioctl_enum_input(struct file *file, void *fh,
> >>>                               struct v4l2_input *input)
> >>>  {
> >>> @@ -1323,8 +1276,8 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >>>       .vidioc_expbuf = vb2_ioctl_expbuf,
> >>>       .vidioc_dqbuf = vb2_ioctl_dqbuf,
> >>>       .vidioc_create_bufs = vb2_ioctl_create_bufs,
> >>> -     .vidioc_streamon = uvc_ioctl_streamon,
> >>> -     .vidioc_streamoff = uvc_ioctl_streamoff,
> >>> +     .vidioc_streamon = vb2_ioctl_streamon,
> >>> +     .vidioc_streamoff = vb2_ioctl_streamoff,
> >>>       .vidioc_enum_input = uvc_ioctl_enum_input,
> >>>       .vidioc_g_input = uvc_ioctl_g_input,
> >>>       .vidioc_s_input = uvc_ioctl_s_input,
> >>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> >>> index 3ddbf065a2cbae40ee48cb06f84ca8f0052990c4..f895f690f7cdc1af942d5f3a5f10e9dd1c956a35 100644
> >>> --- a/drivers/media/usb/uvc/uvcvideo.h
> >>> +++ b/drivers/media/usb/uvc/uvcvideo.h
> >>> @@ -626,7 +626,6 @@ struct uvc_fh {
> >>>       struct uvc_video_chain *chain;
> >>>       struct uvc_streaming *stream;
> >>>       unsigned int pending_async_ctrls;
> >>> -     bool is_streaming;
> >>>  };
> >>>
> >>>  /* ------------------------------------------------------------------------

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Ricardo Ribalda]

Hi Laurent, Hi Hans
> > If this isn't fixed, then at least add a comment explaining why you test for
> > != V4L2_BUF_TYPE_META_CAPTURE before calling uvc_pm_put. It's not obvious.
>
> Agreed.

Maybe this is better than a comment?

diff --git a/drivers/media/usb/uvc/uvc_queue.c
b/drivers/media/usb/uvc/uvc_queue.c
index 72c5494dee9f..7f9d731df32c 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -39,8 +39,6 @@ static inline struct uvc_buffer
*uvc_vbuf_to_buffer(struct vb2_v4l2_buffer *buf)

 /*
  * Return all queued buffers to videobuf2 in the requested state.
- *
- * This function must be called with the queue spinlock held.
  */
 static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
                               enum uvc_buffer_state state)
@@ -49,6 +47,8 @@ static void uvc_queue_return_buffers(struct
uvc_video_queue *queue,
                                        ? VB2_BUF_STATE_ERROR
                                        : VB2_BUF_STATE_QUEUED;

+       spin_lock_irq(&queue->irqlock);
+
        while (!list_empty(&queue->irqqueue)) {
                struct uvc_buffer *buf = list_first_entry(&queue->irqqueue,
                                                          struct uvc_buffer,
@@ -57,6 +57,8 @@ static void uvc_queue_return_buffers(struct
uvc_video_queue *queue,
                buf->state = state;
                vb2_buffer_done(&buf->buf.vb2_buf, vb2_state);
        }
+
+       spin_unlock_irq(&queue->irqlock);
 }

 /* -----------------------------------------------------------------------------
@@ -157,7 +159,7 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
                uvc_video_clock_update(stream, vbuf, buf);
 }

-static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
+static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
 {
        struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
        struct uvc_streaming *stream = uvc_queue_to_stream(queue);
@@ -171,25 +173,29 @@ static int uvc_start_streaming(struct vb2_queue
*vq, unsigned int count)
        if (ret == 0)
                return 0;

-       spin_lock_irq(&queue->irqlock);
        uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
-       spin_unlock_irq(&queue->irqlock);

        return ret;
 }

-static void uvc_stop_streaming(struct vb2_queue *vq)
+static void uvc_stop_streaming_meta(struct vb2_queue *vq)
 {
        struct uvc_video_queue *queue = vb2_get_drv_priv(vq);

        lockdep_assert_irqs_enabled();

-       if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
-               uvc_video_stop_streaming(uvc_queue_to_stream(queue));
+       uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
+}
+
+static void uvc_stop_streaming_video(struct vb2_queue *vq)
+{
+       struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
+
+       lockdep_assert_irqs_enabled();
+
+       uvc_video_stop_streaming(uvc_queue_to_stream(queue));

-       spin_lock_irq(&queue->irqlock);
        uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
-       spin_unlock_irq(&queue->irqlock);
 }

 static const struct vb2_ops uvc_queue_qops = {
@@ -197,15 +203,15 @@ static const struct vb2_ops uvc_queue_qops = {
        .buf_prepare = uvc_buffer_prepare,
        .buf_queue = uvc_buffer_queue,
        .buf_finish = uvc_buffer_finish,
-       .start_streaming = uvc_start_streaming,
-       .stop_streaming = uvc_stop_streaming,
+       .start_streaming = uvc_start_streaming_video,
+       .stop_streaming = uvc_stop_streaming_video,
 };

 static const struct vb2_ops uvc_meta_queue_qops = {
        .queue_setup = uvc_queue_setup,
        .buf_prepare = uvc_buffer_prepare,
        .buf_queue = uvc_buffer_queue,
-       .stop_streaming = uvc_stop_streaming,
+       .stop_streaming = uvc_stop_streaming_meta,
 };

 int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)



-- 
Ricardo Ribalda

Re: [PATCH v2 3/3] media: uvcvideo: Remove stream->is_streaming field

[Hans Verkuil]

On 02/06/2025 16:38, Ricardo Ribalda wrote:
> Hi Laurent, Hi Hans
>>> If this isn't fixed, then at least add a comment explaining why you test for
>>> != V4L2_BUF_TYPE_META_CAPTURE before calling uvc_pm_put. It's not obvious.
>>
>> Agreed.
> 
> Maybe this is better than a comment?

Yes, that's better.

Regards,

	Hans

> 
> diff --git a/drivers/media/usb/uvc/uvc_queue.c
> b/drivers/media/usb/uvc/uvc_queue.c
> index 72c5494dee9f..7f9d731df32c 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -39,8 +39,6 @@ static inline struct uvc_buffer
> *uvc_vbuf_to_buffer(struct vb2_v4l2_buffer *buf)
> 
>  /*
>   * Return all queued buffers to videobuf2 in the requested state.
> - *
> - * This function must be called with the queue spinlock held.
>   */
>  static void uvc_queue_return_buffers(struct uvc_video_queue *queue,
>                                enum uvc_buffer_state state)
> @@ -49,6 +47,8 @@ static void uvc_queue_return_buffers(struct
> uvc_video_queue *queue,
>                                         ? VB2_BUF_STATE_ERROR
>                                         : VB2_BUF_STATE_QUEUED;
> 
> +       spin_lock_irq(&queue->irqlock);
> +
>         while (!list_empty(&queue->irqqueue)) {
>                 struct uvc_buffer *buf = list_first_entry(&queue->irqqueue,
>                                                           struct uvc_buffer,
> @@ -57,6 +57,8 @@ static void uvc_queue_return_buffers(struct
> uvc_video_queue *queue,
>                 buf->state = state;
>                 vb2_buffer_done(&buf->buf.vb2_buf, vb2_state);
>         }
> +
> +       spin_unlock_irq(&queue->irqlock);
>  }
> 
>  /* -----------------------------------------------------------------------------
> @@ -157,7 +159,7 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
>                 uvc_video_clock_update(stream, vbuf, buf);
>  }
> 
> -static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
> +static int uvc_start_streaming_video(struct vb2_queue *vq, unsigned int count)
>  {
>         struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
>         struct uvc_streaming *stream = uvc_queue_to_stream(queue);
> @@ -171,25 +173,29 @@ static int uvc_start_streaming(struct vb2_queue
> *vq, unsigned int count)
>         if (ret == 0)
>                 return 0;
> 
> -       spin_lock_irq(&queue->irqlock);
>         uvc_queue_return_buffers(queue, UVC_BUF_STATE_QUEUED);
> -       spin_unlock_irq(&queue->irqlock);
> 
>         return ret;
>  }
> 
> -static void uvc_stop_streaming(struct vb2_queue *vq)
> +static void uvc_stop_streaming_meta(struct vb2_queue *vq)
>  {
>         struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> 
>         lockdep_assert_irqs_enabled();
> 
> -       if (vq->type != V4L2_BUF_TYPE_META_CAPTURE)
> -               uvc_video_stop_streaming(uvc_queue_to_stream(queue));
> +       uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> +}
> +
> +static void uvc_stop_streaming_video(struct vb2_queue *vq)
> +{
> +       struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
> +
> +       lockdep_assert_irqs_enabled();
> +
> +       uvc_video_stop_streaming(uvc_queue_to_stream(queue));
> 
> -       spin_lock_irq(&queue->irqlock);
>         uvc_queue_return_buffers(queue, UVC_BUF_STATE_ERROR);
> -       spin_unlock_irq(&queue->irqlock);
>  }
> 
>  static const struct vb2_ops uvc_queue_qops = {
> @@ -197,15 +203,15 @@ static const struct vb2_ops uvc_queue_qops = {
>         .buf_prepare = uvc_buffer_prepare,
>         .buf_queue = uvc_buffer_queue,
>         .buf_finish = uvc_buffer_finish,
> -       .start_streaming = uvc_start_streaming,
> -       .stop_streaming = uvc_stop_streaming,
> +       .start_streaming = uvc_start_streaming_video,
> +       .stop_streaming = uvc_stop_streaming_video,
>  };
> 
>  static const struct vb2_ops uvc_meta_queue_qops = {
>         .queue_setup = uvc_queue_setup,
>         .buf_prepare = uvc_buffer_prepare,
>         .buf_queue = uvc_buffer_queue,
> -       .stop_streaming = uvc_stop_streaming,
> +       .stop_streaming = uvc_stop_streaming_meta,
>  };
> 
>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> 
> 
> 

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Laurent Pinchart]

Hi Ricardo, Hans,

On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> From: Hans Verkuil <hans@jjverkuil.nl>
> 
> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> 
> This patch switches uvc over to those helpers, which removes a lot of
> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling

How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
patch does related to priority is replace the per-chain priority
handling with a per-device (as in uvc_device) priority, as the default
is to use the prio state from v4l2_device. I think this is actually
incorrect, a UVC device can have multiple independent streaming
interfaces, so the priority ioctls should no operate on a device-wide
prio state. Am I missing something ?

> and allows us
> to drop the 'privileges' scheme, since that's now handled inside the vb2
> helpers.

That part is correct. The driver implements a privilege-management
system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
handlers, as the ioctl handlers didn't exist back then.

Please reword the commit message to make this clearer. If the prio
change is also desired, it should be split in a separate patch.

> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> 
> This patch introduces a change on behavior on the uvcdriver to be
> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> S_FORMAT do no grant exclusive ownership of the device.

There are other changes in behaviour worth noting, some small, some
quite substantial. Let's start with the small one: .vidioc_querybuf()
now succeeds when the queue is busy. It seems a check may be missing in
v4l2-compliance for this.

The bigger change is related to locking. See below.

> Reviewed-by: Hans de Goede <hansg@kernel.org>
> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
>  5 files changed, 30 insertions(+), 443 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
>  	INIT_LIST_HEAD(&chain->entities);
>  	mutex_init(&chain->ctrl_mutex);
>  	chain->dev = dev;
> -	v4l2_prio_init(&chain->prio);
>  
>  	return chain;
>  }
> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
>  		if (!video_is_registered(&stream->vdev))
>  			continue;
>  
> -		/*
> -		 * For stream->vdev we follow the same logic as:
> -		 * vb2_video_unregister_device().
> -		 */
> -
> -		/* 1. Take a reference to vdev */
> -		get_device(&stream->vdev.dev);
> -
> -		/* 2. Ensure that no new ioctls can be called. */
> -		video_unregister_device(&stream->vdev);
> -
> -		/* 3. Wait for old ioctls to finish. */
> -		mutex_lock(&stream->mutex);
> -
> -		/* 4. Stop streaming. */
> -		uvc_queue_release(&stream->queue);
> -
> -		mutex_unlock(&stream->mutex);
> -
> -		put_device(&stream->vdev.dev);
> -
> -		/*
> -		 * For stream->meta.vdev we can directly call:
> -		 * vb2_video_unregister_device().
> -		 */
> +		vb2_video_unregister_device(&stream->vdev);
>  		vb2_video_unregister_device(&stream->meta.vdev);
>  
>  		/*
> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
>  	vdev->fops = fops;
>  	vdev->ioctl_ops = ioctl_ops;
>  	vdev->release = uvc_release;
> -	vdev->prio = &stream->chain->prio;
> +	vdev->queue = &queue->queue;
> +	vdev->lock = &queue->mutex;

This will cause the ioctl handlers to use queue->mutex for all ioctls
(both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
coarse, that should be mentioned in the commit message.

>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
>  		vdev->vfl_dir = VFL_DIR_TX;
>  	else
> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
>  		if (stream->intf == intf) {
>  			ret = uvc_video_resume(stream, reset);
>  			if (ret < 0)
> -				uvc_queue_streamoff(&stream->queue,
> -						    stream->queue.queue.type);
> +				vb2_streamoff(&stream->queue.queue,
> +					      stream->queue.queue.type);

This doesn't take any lock anymore. Can that be a problem ?

>  			return ret;
>  		}
>  	}
> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> --- a/drivers/media/usb/uvc/uvc_metadata.c
> +++ b/drivers/media/usb/uvc/uvc_metadata.c
> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
>  	 */
>  	mutex_lock(&stream->mutex);

Is this lock still needed ? More broadly speaking, what's the remaining
purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
drop queue->mutex, and use stream->mutex everywhere instead ?

>  
> -	if (uvc_queue_allocated(&stream->queue))
> +	if (vb2_is_busy(&stream->meta.queue.queue))
>  		ret = -EBUSY;
>  	else
>  		stream->meta.format = fmt->dataformat;
> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
>  
>  	stream->meta.format = V4L2_META_FMT_UVC;
>  
> -	/*
> -	 * The video interface queue uses manual locking and thus does not set
> -	 * the queue pointer. Set it manually here.
> -	 */
> -	vdev->queue = &queue->queue;
> -
>  	return uvc_register_video_device(dev, stream, vdev, queue,
>  					 V4L2_BUF_TYPE_META_CAPTURE,
>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> --- a/drivers/media/usb/uvc/uvc_queue.c
> +++ b/drivers/media/usb/uvc/uvc_queue.c
> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>  	return 0;
>  }
>  
> -void uvc_queue_release(struct uvc_video_queue *queue)
> -{
> -	mutex_lock(&queue->mutex);
> -	vb2_queue_release(&queue->queue);
> -	mutex_unlock(&queue->mutex);
> -}
> -
> -/* -----------------------------------------------------------------------------
> - * V4L2 queue operations
> - */
> -
> -int uvc_request_buffers(struct uvc_video_queue *queue,
> -			struct v4l2_requestbuffers *rb)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_reqbufs(&queue->queue, rb);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret ? ret : rb->count;
> -}
> -
> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_querybuf(&queue->queue, buf);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_create_buffers(struct uvc_video_queue *queue,
> -		       struct v4l2_create_buffers *cb)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_create_bufs(&queue->queue, cb);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> -		     struct media_device *mdev, struct v4l2_buffer *buf)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_export_buffer(struct uvc_video_queue *queue,
> -		      struct v4l2_exportbuffer *exp)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_expbuf(&queue->queue, exp);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> -		       int nonblocking)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_streamon(&queue->queue, type);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> -{
> -	int ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_streamoff(&queue->queue, type);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> -{
> -	return vb2_mmap(&queue->queue, vma);
> -}
> -
> -#ifndef CONFIG_MMU
> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> -		unsigned long pgoff)
> -{
> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> -}
> -#endif
> -
> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> -			    poll_table *wait)
> -{
> -	__poll_t ret;
> -
> -	mutex_lock(&queue->mutex);
> -	ret = vb2_poll(&queue->queue, file, wait);
> -	mutex_unlock(&queue->mutex);
> -
> -	return ret;
> -}
> -
>  /* -----------------------------------------------------------------------------
>   *
>   */
>  
> -/*
> - * Check if buffers have been allocated.
> - */
> -int uvc_queue_allocated(struct uvc_video_queue *queue)
> -{
> -	int allocated;
> -
> -	mutex_lock(&queue->mutex);
> -	allocated = vb2_is_busy(&queue->queue);
> -	mutex_unlock(&queue->mutex);
> -
> -	return allocated;
> -}
> -
>  /*
>   * Cancel the video buffers queue.
>   *
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
>  	usb_autopm_put_interface(dev->intf);
>  }
>  
> -static int uvc_acquire_privileges(struct uvc_fh *handle);
> -
>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
>  				      struct uvc_control_mapping *map,
>  				      const struct uvc_xu_control_mapping *xmap)
> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>  	const struct uvc_frame *frame;
>  	int ret;
>  
> -	ret = uvc_acquire_privileges(handle);
> -	if (ret < 0)
> -		return ret;
> -
>  	if (fmt->type != stream->type)
>  		return -EINVAL;
>  
> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>  		return ret;
>  
>  	mutex_lock(&stream->mutex);
> -
> -	if (uvc_queue_allocated(&stream->queue)) {
> +	if (vb2_is_busy(&stream->queue.queue)) {
>  		ret = -EBUSY;
>  		goto done;
>  	}
> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>  	unsigned int i;
>  	int ret;
>  
> -	ret = uvc_acquire_privileges(handle);
> -	if (ret < 0)
> -		return ret;
> -
>  	if (parm->type != stream->type)
>  		return -EINVAL;
>  
> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>  	return 0;
>  }
>  
> -/* ------------------------------------------------------------------------
> - * Privilege management
> - */
> -
> -/*
> - * Privilege management is the multiple-open implementation basis. The current
> - * implementation is completely transparent for the end-user and doesn't
> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> - * Those ioctls enable finer control on the device (by making possible for a
> - * user to request exclusive access to a device), but are not mature yet.
> - * Switching to the V4L2 priority mechanism might be considered in the future
> - * if this situation changes.
> - *
> - * Each open instance of a UVC device can either be in a privileged or
> - * unprivileged state. Only a single instance can be in a privileged state at
> - * a given time. Trying to perform an operation that requires privileges will
> - * automatically acquire the required privileges if possible, or return -EBUSY
> - * otherwise. Privileges are dismissed when closing the instance or when
> - * freeing the video buffers using VIDIOC_REQBUFS.
> - *
> - * Operations that require privileges are:
> - *
> - * - VIDIOC_S_INPUT
> - * - VIDIOC_S_PARM
> - * - VIDIOC_S_FMT
> - * - VIDIOC_CREATE_BUFS
> - * - VIDIOC_REQBUFS
> - */
> -static int uvc_acquire_privileges(struct uvc_fh *handle)
> -{
> -	/* Always succeed if the handle is already privileged. */
> -	if (handle->state == UVC_HANDLE_ACTIVE)
> -		return 0;
> -
> -	/* Check if the device already has a privileged handle. */
> -	if (atomic_inc_return(&handle->stream->active) != 1) {
> -		atomic_dec(&handle->stream->active);
> -		return -EBUSY;
> -	}
> -
> -	handle->state = UVC_HANDLE_ACTIVE;
> -	return 0;
> -}
> -
> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> -{
> -	if (handle->state == UVC_HANDLE_ACTIVE)
> -		atomic_dec(&handle->stream->active);
> -
> -	handle->state = UVC_HANDLE_PASSIVE;
> -}
> -
> -static int uvc_has_privileges(struct uvc_fh *handle)
> -{
> -	return handle->state == UVC_HANDLE_ACTIVE;
> -}
> -
>  /* ------------------------------------------------------------------------
>   * V4L2 file operations
>   */
> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
>  	v4l2_fh_add(&handle->vfh);
>  	handle->chain = stream->chain;
>  	handle->stream = stream;
> -	handle->state = UVC_HANDLE_PASSIVE;
>  	file->private_data = handle;
>  
>  	return 0;
> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
>  
>  	uvc_ctrl_cleanup_fh(handle);
>  
> -	/* Only free resources if this is a privileged handle. */
> -	if (uvc_has_privileges(handle))
> -		uvc_queue_release(&stream->queue);
> -
>  	if (handle->is_streaming)
>  		uvc_pm_put(stream->dev);
>  
>  	/* Release the file handle. */
> -	uvc_dismiss_privileges(handle);
> -	v4l2_fh_del(&handle->vfh);
> -	v4l2_fh_exit(&handle->vfh);
> -	kfree(handle);
> +	vb2_fop_release(file);
>  	file->private_data = NULL;

You can drop setting private_data to NULL, it's done by
v4l2_fh_release() called by vb2_fop_release().

>  
>  	return 0;
> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>  }
>  
> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> -			     struct v4l2_requestbuffers *rb)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -	int ret;
> -
> -	ret = uvc_acquire_privileges(handle);
> -	if (ret < 0)
> -		return ret;
> -
> -	mutex_lock(&stream->mutex);
> -	ret = uvc_request_buffers(&stream->queue, rb);
> -	mutex_unlock(&stream->mutex);
> -	if (ret < 0)
> -		return ret;
> -
> -	if (ret == 0)
> -		uvc_dismiss_privileges(handle);
> -
> -	return 0;
> -}
> -
> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> -			      struct v4l2_buffer *buf)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	return uvc_query_buffer(&stream->queue, buf);
> -}
> -
> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	return uvc_queue_buffer(&stream->queue,
> -				stream->vdev.v4l2_dev->mdev, buf);
> -}
> -
> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> -			    struct v4l2_exportbuffer *exp)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	return uvc_export_buffer(&stream->queue, exp);
> -}
> -
> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	return uvc_dequeue_buffer(&stream->queue, buf,
> -				  file->f_flags & O_NONBLOCK);
> -}
> -
> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> -				  struct v4l2_create_buffers *cb)
> -{
> -	struct uvc_fh *handle = fh;
> -	struct uvc_streaming *stream = handle->stream;
> -	int ret;
> -
> -	ret = uvc_acquire_privileges(handle);
> -	if (ret < 0)
> -		return ret;
> -
> -	return uvc_create_buffers(&stream->queue, cb);
> -}
> -
>  static int uvc_ioctl_streamon(struct file *file, void *fh,
>  			      enum v4l2_buf_type type)
>  {
> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>  	struct uvc_streaming *stream = handle->stream;
>  	int ret;
>  
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	guard(mutex)(&stream->mutex);
> -
>  	if (handle->is_streaming)
>  		return 0;
>  
> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>  	if (ret)
>  		return ret;
>  
> -	ret = uvc_queue_streamon(&stream->queue, type);
> +	ret = vb2_ioctl_streamon(file, fh, type);
>  	if (ret) {
>  		uvc_pm_put(stream->dev);
>  		return ret;
> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
>  {
>  	struct uvc_fh *handle = fh;
>  	struct uvc_streaming *stream = handle->stream;
> +	int ret;
>  
> -	if (!uvc_has_privileges(handle))
> -		return -EBUSY;
> -
> -	guard(mutex)(&stream->mutex);
> +	ret = vb2_ioctl_streamoff(file, fh, type);
> +	if (ret)
> +		return ret;
>  
> -	uvc_queue_streamoff(&stream->queue, type);
>  	if (handle->is_streaming) {
>  		handle->is_streaming = false;
>  		uvc_pm_put(stream->dev);
> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
>  {
>  	struct uvc_fh *handle = fh;
> +	struct uvc_streaming *stream = handle->stream;
>  	struct uvc_video_chain *chain = handle->chain;
>  	u8 *buf;
>  	int ret;
>  
> -	ret = uvc_acquire_privileges(handle);
> -	if (ret < 0)
> -		return ret;
> +	if (vb2_is_busy(&stream->queue.queue))
> +		return -EBUSY;
>  
>  	if (chain->selector == NULL ||
>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>  	return ret;
>  }
>  
> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> -		    size_t count, loff_t *ppos)
> -{
> -	struct uvc_fh *handle = file->private_data;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> -	return -EINVAL;
> -}
> -
> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> -{
> -	struct uvc_fh *handle = file->private_data;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> -
> -	return uvc_queue_mmap(&stream->queue, vma);
> -}
> -
> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> -{
> -	struct uvc_fh *handle = file->private_data;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> -
> -	return uvc_queue_poll(&stream->queue, file, wait);
> -}
> -
> -#ifndef CONFIG_MMU
> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> -		unsigned long addr, unsigned long len, unsigned long pgoff,
> -		unsigned long flags)
> -{
> -	struct uvc_fh *handle = file->private_data;
> -	struct uvc_streaming *stream = handle->stream;
> -
> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> -
> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> -}
> -#endif
> -
>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
> -	.vidioc_querybuf = uvc_ioctl_querybuf,
> -	.vidioc_qbuf = uvc_ioctl_qbuf,
> -	.vidioc_expbuf = uvc_ioctl_expbuf,
> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>  	.vidioc_streamon = uvc_ioctl_streamon,
>  	.vidioc_streamoff = uvc_ioctl_streamoff,
>  	.vidioc_enum_input = uvc_ioctl_enum_input,
> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
>  #ifdef CONFIG_COMPAT
>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
>  #endif
> -	.read		= uvc_v4l2_read,
> -	.mmap		= uvc_v4l2_mmap,
> -	.poll		= uvc_v4l2_poll,
> +	.mmap		= vb2_fop_mmap,
> +	.poll		= vb2_fop_poll,
>  #ifndef CONFIG_MMU
> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
>  #endif
>  };
>  
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -326,7 +326,10 @@ struct uvc_buffer {
>  
>  struct uvc_video_queue {
>  	struct vb2_queue queue;
> -	struct mutex mutex;			/* Protects queue */
> +	struct mutex mutex;			/*
> +						 * Serializes vb2_queue and
> +						 * fops
> +						 */
>  
>  	unsigned int flags;
>  	unsigned int buf_used;
> @@ -349,7 +352,6 @@ struct uvc_video_chain {
>  						 * uvc_fh.pending_async_ctrls
>  						 */
>  
> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
>  	u32 caps;				/* V4L2 chain-wide caps */
>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
>  };
> @@ -619,16 +621,10 @@ struct uvc_device {
>  	struct uvc_entity *gpio_unit;
>  };
>  
> -enum uvc_handle_state {
> -	UVC_HANDLE_PASSIVE	= 0,
> -	UVC_HANDLE_ACTIVE	= 1,
> -};
> -
>  struct uvc_fh {
>  	struct v4l2_fh vfh;
>  	struct uvc_video_chain *chain;
>  	struct uvc_streaming *stream;
> -	enum uvc_handle_state state;
>  	unsigned int pending_async_ctrls;
>  	bool is_streaming;
>  };
> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>  
>  /* Video buffers queue management. */
>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> -void uvc_queue_release(struct uvc_video_queue *queue);
> -int uvc_request_buffers(struct uvc_video_queue *queue,
> -			struct v4l2_requestbuffers *rb);
> -int uvc_query_buffer(struct uvc_video_queue *queue,
> -		     struct v4l2_buffer *v4l2_buf);
> -int uvc_create_buffers(struct uvc_video_queue *queue,
> -		       struct v4l2_create_buffers *v4l2_cb);
> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> -		     struct media_device *mdev,
> -		     struct v4l2_buffer *v4l2_buf);
> -int uvc_export_buffer(struct uvc_video_queue *queue,
> -		      struct v4l2_exportbuffer *exp);
> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>  					 struct uvc_buffer *buf);
>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> -int uvc_queue_mmap(struct uvc_video_queue *queue,
> -		   struct vm_area_struct *vma);
> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> -			poll_table *wait);
> -#ifndef CONFIG_MMU
> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> -					  unsigned long pgoff);
> -#endif
> -int uvc_queue_allocated(struct uvc_video_queue *queue);
>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>  {
>  	return vb2_is_streaming(&queue->queue);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Ricardo Ribalda]

Hi Laurent

On Mon, 2 Jun 2025 at 20:31, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo, Hans,
>
> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> > From: Hans Verkuil <hans@jjverkuil.nl>
> >
> > When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> >
> > This patch switches uvc over to those helpers, which removes a lot of
> > boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
>
> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> patch does related to priority is replace the per-chain priority
> handling with a per-device (as in uvc_device) priority, as the default
> is to use the prio state from v4l2_device. I think this is actually
> incorrect, a UVC device can have multiple independent streaming
> interfaces, so the priority ioctls should no operate on a device-wide
> prio state. Am I missing something ?

You are correct.
The uvcvideo is the only driver that does not use the prio state from
v4l2_device and it makes v4l2-core a bit more complicated.

I have not seen a real use of  VIDIOC_[GS]_PRIORITY, so being a bit
incorrect in favor of simplicity is probably a good trade-off.
Anyway it is an easy change to split into a different patch, we can
have the discussion about prio there.


>
> > and allows us
> > to drop the 'privileges' scheme, since that's now handled inside the vb2
> > helpers.
>
> That part is correct. The driver implements a privilege-management
> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> handlers, as the ioctl handlers didn't exist back then.
>
> Please reword the commit message to make this clearer. If the prio
> change is also desired, it should be split in a separate patch.
>
> > This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> >  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> >
> > This patch introduces a change on behavior on the uvcdriver to be
> > aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> > S_FORMAT do no grant exclusive ownership of the device.
>
> There are other changes in behaviour worth noting, some small, some
> quite substantial. Let's start with the small one: .vidioc_querybuf()
> now succeeds when the queue is busy. It seems a check may be missing in
> v4l2-compliance for this.

Agree,
After we land this we can add the check to v4l2-compliance.

>
> The bigger change is related to locking. See below.
>
> > Reviewed-by: Hans de Goede <hansg@kernel.org>
> > Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> > Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> > Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> >  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> >  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> >  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> >  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> >  5 files changed, 30 insertions(+), 443 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> >       INIT_LIST_HEAD(&chain->entities);
> >       mutex_init(&chain->ctrl_mutex);
> >       chain->dev = dev;
> > -     v4l2_prio_init(&chain->prio);
> >
> >       return chain;
> >  }
> > @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> >               if (!video_is_registered(&stream->vdev))
> >                       continue;
> >
> > -             /*
> > -              * For stream->vdev we follow the same logic as:
> > -              * vb2_video_unregister_device().
> > -              */
> > -
> > -             /* 1. Take a reference to vdev */
> > -             get_device(&stream->vdev.dev);
> > -
> > -             /* 2. Ensure that no new ioctls can be called. */
> > -             video_unregister_device(&stream->vdev);
> > -
> > -             /* 3. Wait for old ioctls to finish. */
> > -             mutex_lock(&stream->mutex);
> > -
> > -             /* 4. Stop streaming. */
> > -             uvc_queue_release(&stream->queue);
> > -
> > -             mutex_unlock(&stream->mutex);
> > -
> > -             put_device(&stream->vdev.dev);
> > -
> > -             /*
> > -              * For stream->meta.vdev we can directly call:
> > -              * vb2_video_unregister_device().
> > -              */
> > +             vb2_video_unregister_device(&stream->vdev);
> >               vb2_video_unregister_device(&stream->meta.vdev);
> >
> >               /*
> > @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> >       vdev->fops = fops;
> >       vdev->ioctl_ops = ioctl_ops;
> >       vdev->release = uvc_release;
> > -     vdev->prio = &stream->chain->prio;
> > +     vdev->queue = &queue->queue;
> > +     vdev->lock = &queue->mutex;
>
> This will cause the ioctl handlers to use queue->mutex for all ioctls
> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> coarse, that should be mentioned in the commit message.
>
> >       if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> >               vdev->vfl_dir = VFL_DIR_TX;
> >       else
> > @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> >               if (stream->intf == intf) {
> >                       ret = uvc_video_resume(stream, reset);
> >                       if (ret < 0)
> > -                             uvc_queue_streamoff(&stream->queue,
> > -                                                 stream->queue.queue.type);
> > +                             vb2_streamoff(&stream->queue.queue,
> > +                                           stream->queue.queue.type);
>
> This doesn't take any lock anymore. Can that be a problem ?
ack
Probably better to keep the same lock pattern as before. I am adding
mutex_lock/unlock

>
> >                       return ret;
> >               }
> >       }
> > diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> > index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> > --- a/drivers/media/usb/uvc/uvc_metadata.c
> > +++ b/drivers/media/usb/uvc/uvc_metadata.c
> > @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> >        */
> >       mutex_lock(&stream->mutex);
>
> Is this lock still needed ? More broadly speaking, what's the remaining
> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> drop queue->mutex, and use stream->mutex everywhere instead ?

Good question, this is the first thing that I tried, and there are
plenty of nested locking that are wrong:
lock(stream->mutex)
  lock(stream->muex)

It is probably fixable, but we can do that as a follow-up patch.

>
> >
> > -     if (uvc_queue_allocated(&stream->queue))
> > +     if (vb2_is_busy(&stream->meta.queue.queue))
> >               ret = -EBUSY;
> >       else
> >               stream->meta.format = fmt->dataformat;
> > @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> >
> >       stream->meta.format = V4L2_META_FMT_UVC;
> >
> > -     /*
> > -      * The video interface queue uses manual locking and thus does not set
> > -      * the queue pointer. Set it manually here.
> > -      */
> > -     vdev->queue = &queue->queue;
> > -
> >       return uvc_register_video_device(dev, stream, vdev, queue,
> >                                        V4L2_BUF_TYPE_META_CAPTURE,
> >                                        &uvc_meta_fops, &uvc_meta_ioctl_ops);
> > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> > --- a/drivers/media/usb/uvc/uvc_queue.c
> > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >       return 0;
> >  }
> >
> > -void uvc_queue_release(struct uvc_video_queue *queue)
> > -{
> > -     mutex_lock(&queue->mutex);
> > -     vb2_queue_release(&queue->queue);
> > -     mutex_unlock(&queue->mutex);
> > -}
> > -
> > -/* -----------------------------------------------------------------------------
> > - * V4L2 queue operations
> > - */
> > -
> > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > -                     struct v4l2_requestbuffers *rb)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_reqbufs(&queue->queue, rb);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret ? ret : rb->count;
> > -}
> > -
> > -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_querybuf(&queue->queue, buf);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > -                    struct v4l2_create_buffers *cb)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_create_bufs(&queue->queue, cb);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > -                  struct media_device *mdev, struct v4l2_buffer *buf)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_qbuf(&queue->queue, mdev, buf);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > -                   struct v4l2_exportbuffer *exp)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_expbuf(&queue->queue, exp);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> > -                    int nonblocking)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_streamon(&queue->queue, type);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > -{
> > -     int ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_streamoff(&queue->queue, type);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> > -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> > -{
> > -     return vb2_mmap(&queue->queue, vma);
> > -}
> > -
> > -#ifndef CONFIG_MMU
> > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > -             unsigned long pgoff)
> > -{
> > -     return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> > -}
> > -#endif
> > -
> > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > -                         poll_table *wait)
> > -{
> > -     __poll_t ret;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     ret = vb2_poll(&queue->queue, file, wait);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return ret;
> > -}
> > -
> >  /* -----------------------------------------------------------------------------
> >   *
> >   */
> >
> > -/*
> > - * Check if buffers have been allocated.
> > - */
> > -int uvc_queue_allocated(struct uvc_video_queue *queue)
> > -{
> > -     int allocated;
> > -
> > -     mutex_lock(&queue->mutex);
> > -     allocated = vb2_is_busy(&queue->queue);
> > -     mutex_unlock(&queue->mutex);
> > -
> > -     return allocated;
> > -}
> > -
> >  /*
> >   * Cancel the video buffers queue.
> >   *
> > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> >       usb_autopm_put_interface(dev->intf);
> >  }
> >
> > -static int uvc_acquire_privileges(struct uvc_fh *handle);
> > -
> >  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> >                                     struct uvc_control_mapping *map,
> >                                     const struct uvc_xu_control_mapping *xmap)
> > @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >       const struct uvc_frame *frame;
> >       int ret;
> >
> > -     ret = uvc_acquire_privileges(handle);
> > -     if (ret < 0)
> > -             return ret;
> > -
> >       if (fmt->type != stream->type)
> >               return -EINVAL;
> >
> > @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >               return ret;
> >
> >       mutex_lock(&stream->mutex);
> > -
> > -     if (uvc_queue_allocated(&stream->queue)) {
> > +     if (vb2_is_busy(&stream->queue.queue)) {
> >               ret = -EBUSY;
> >               goto done;
> >       }
> > @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >       unsigned int i;
> >       int ret;
> >
> > -     ret = uvc_acquire_privileges(handle);
> > -     if (ret < 0)
> > -             return ret;
> > -
> >       if (parm->type != stream->type)
> >               return -EINVAL;
> >
> > @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >       return 0;
> >  }
> >
> > -/* ------------------------------------------------------------------------
> > - * Privilege management
> > - */
> > -
> > -/*
> > - * Privilege management is the multiple-open implementation basis. The current
> > - * implementation is completely transparent for the end-user and doesn't
> > - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> > - * Those ioctls enable finer control on the device (by making possible for a
> > - * user to request exclusive access to a device), but are not mature yet.
> > - * Switching to the V4L2 priority mechanism might be considered in the future
> > - * if this situation changes.
> > - *
> > - * Each open instance of a UVC device can either be in a privileged or
> > - * unprivileged state. Only a single instance can be in a privileged state at
> > - * a given time. Trying to perform an operation that requires privileges will
> > - * automatically acquire the required privileges if possible, or return -EBUSY
> > - * otherwise. Privileges are dismissed when closing the instance or when
> > - * freeing the video buffers using VIDIOC_REQBUFS.
> > - *
> > - * Operations that require privileges are:
> > - *
> > - * - VIDIOC_S_INPUT
> > - * - VIDIOC_S_PARM
> > - * - VIDIOC_S_FMT
> > - * - VIDIOC_CREATE_BUFS
> > - * - VIDIOC_REQBUFS
> > - */
> > -static int uvc_acquire_privileges(struct uvc_fh *handle)
> > -{
> > -     /* Always succeed if the handle is already privileged. */
> > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > -             return 0;
> > -
> > -     /* Check if the device already has a privileged handle. */
> > -     if (atomic_inc_return(&handle->stream->active) != 1) {
> > -             atomic_dec(&handle->stream->active);
> > -             return -EBUSY;
> > -     }
> > -
> > -     handle->state = UVC_HANDLE_ACTIVE;
> > -     return 0;
> > -}
> > -
> > -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> > -{
> > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > -             atomic_dec(&handle->stream->active);
> > -
> > -     handle->state = UVC_HANDLE_PASSIVE;
> > -}
> > -
> > -static int uvc_has_privileges(struct uvc_fh *handle)
> > -{
> > -     return handle->state == UVC_HANDLE_ACTIVE;
> > -}
> > -
> >  /* ------------------------------------------------------------------------
> >   * V4L2 file operations
> >   */
> > @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> >       v4l2_fh_add(&handle->vfh);
> >       handle->chain = stream->chain;
> >       handle->stream = stream;
> > -     handle->state = UVC_HANDLE_PASSIVE;
> >       file->private_data = handle;
> >
> >       return 0;
> > @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> >
> >       uvc_ctrl_cleanup_fh(handle);
> >
> > -     /* Only free resources if this is a privileged handle. */
> > -     if (uvc_has_privileges(handle))
> > -             uvc_queue_release(&stream->queue);
> > -
> >       if (handle->is_streaming)
> >               uvc_pm_put(stream->dev);
> >
> >       /* Release the file handle. */
> > -     uvc_dismiss_privileges(handle);
> > -     v4l2_fh_del(&handle->vfh);
> > -     v4l2_fh_exit(&handle->vfh);
> > -     kfree(handle);
> > +     vb2_fop_release(file);
> >       file->private_data = NULL;
>
> You can drop setting private_data to NULL, it's done by
> v4l2_fh_release() called by vb2_fop_release().
ack
>
> >
> >       return 0;
> > @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> >       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> >  }
> >
> > -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> > -                          struct v4l2_requestbuffers *rb)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -     int ret;
> > -
> > -     ret = uvc_acquire_privileges(handle);
> > -     if (ret < 0)
> > -             return ret;
> > -
> > -     mutex_lock(&stream->mutex);
> > -     ret = uvc_request_buffers(&stream->queue, rb);
> > -     mutex_unlock(&stream->mutex);
> > -     if (ret < 0)
> > -             return ret;
> > -
> > -     if (ret == 0)
> > -             uvc_dismiss_privileges(handle);
> > -
> > -     return 0;
> > -}
> > -
> > -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> > -                           struct v4l2_buffer *buf)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     return uvc_query_buffer(&stream->queue, buf);
> > -}
> > -
> > -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     return uvc_queue_buffer(&stream->queue,
> > -                             stream->vdev.v4l2_dev->mdev, buf);
> > -}
> > -
> > -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> > -                         struct v4l2_exportbuffer *exp)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     return uvc_export_buffer(&stream->queue, exp);
> > -}
> > -
> > -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     return uvc_dequeue_buffer(&stream->queue, buf,
> > -                               file->f_flags & O_NONBLOCK);
> > -}
> > -
> > -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> > -                               struct v4l2_create_buffers *cb)
> > -{
> > -     struct uvc_fh *handle = fh;
> > -     struct uvc_streaming *stream = handle->stream;
> > -     int ret;
> > -
> > -     ret = uvc_acquire_privileges(handle);
> > -     if (ret < 0)
> > -             return ret;
> > -
> > -     return uvc_create_buffers(&stream->queue, cb);
> > -}
> > -
> >  static int uvc_ioctl_streamon(struct file *file, void *fh,
> >                             enum v4l2_buf_type type)
> >  {
> > @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >       struct uvc_streaming *stream = handle->stream;
> >       int ret;
> >
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     guard(mutex)(&stream->mutex);
> > -
> >       if (handle->is_streaming)
> >               return 0;
> >
> > @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >       if (ret)
> >               return ret;
> >
> > -     ret = uvc_queue_streamon(&stream->queue, type);
> > +     ret = vb2_ioctl_streamon(file, fh, type);
> >       if (ret) {
> >               uvc_pm_put(stream->dev);
> >               return ret;
> > @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> >  {
> >       struct uvc_fh *handle = fh;
> >       struct uvc_streaming *stream = handle->stream;
> > +     int ret;
> >
> > -     if (!uvc_has_privileges(handle))
> > -             return -EBUSY;
> > -
> > -     guard(mutex)(&stream->mutex);
> > +     ret = vb2_ioctl_streamoff(file, fh, type);
> > +     if (ret)
> > +             return ret;
> >
> > -     uvc_queue_streamoff(&stream->queue, type);
> >       if (handle->is_streaming) {
> >               handle->is_streaming = false;
> >               uvc_pm_put(stream->dev);
> > @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> >  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> >  {
> >       struct uvc_fh *handle = fh;
> > +     struct uvc_streaming *stream = handle->stream;
> >       struct uvc_video_chain *chain = handle->chain;
> >       u8 *buf;
> >       int ret;
> >
> > -     ret = uvc_acquire_privileges(handle);
> > -     if (ret < 0)
> > -             return ret;
> > +     if (vb2_is_busy(&stream->queue.queue))
> > +             return -EBUSY;
> >
> >       if (chain->selector == NULL ||
> >           (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> > @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> >       return ret;
> >  }
> >
> > -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> > -                 size_t count, loff_t *ppos)
> > -{
> > -     struct uvc_fh *handle = file->private_data;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> > -     return -EINVAL;
> > -}
> > -
> > -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> > -{
> > -     struct uvc_fh *handle = file->private_data;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > -
> > -     return uvc_queue_mmap(&stream->queue, vma);
> > -}
> > -
> > -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> > -{
> > -     struct uvc_fh *handle = file->private_data;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > -
> > -     return uvc_queue_poll(&stream->queue, file, wait);
> > -}
> > -
> > -#ifndef CONFIG_MMU
> > -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> > -             unsigned long addr, unsigned long len, unsigned long pgoff,
> > -             unsigned long flags)
> > -{
> > -     struct uvc_fh *handle = file->private_data;
> > -     struct uvc_streaming *stream = handle->stream;
> > -
> > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > -
> > -     return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> > -}
> > -#endif
> > -
> >  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >       .vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> >       .vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> > @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >       .vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> >       .vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> >       .vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> > -     .vidioc_reqbufs = uvc_ioctl_reqbufs,
> > -     .vidioc_querybuf = uvc_ioctl_querybuf,
> > -     .vidioc_qbuf = uvc_ioctl_qbuf,
> > -     .vidioc_expbuf = uvc_ioctl_expbuf,
> > -     .vidioc_dqbuf = uvc_ioctl_dqbuf,
> > -     .vidioc_create_bufs = uvc_ioctl_create_bufs,
> > +     .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > +     .vidioc_querybuf = vb2_ioctl_querybuf,
> > +     .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> > +     .vidioc_qbuf = vb2_ioctl_qbuf,
> > +     .vidioc_expbuf = vb2_ioctl_expbuf,
> > +     .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > +     .vidioc_create_bufs = vb2_ioctl_create_bufs,
> >       .vidioc_streamon = uvc_ioctl_streamon,
> >       .vidioc_streamoff = uvc_ioctl_streamoff,
> >       .vidioc_enum_input = uvc_ioctl_enum_input,
> > @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> >  #ifdef CONFIG_COMPAT
> >       .compat_ioctl32 = uvc_v4l2_compat_ioctl32,
> >  #endif
> > -     .read           = uvc_v4l2_read,
> > -     .mmap           = uvc_v4l2_mmap,
> > -     .poll           = uvc_v4l2_poll,
> > +     .mmap           = vb2_fop_mmap,
> > +     .poll           = vb2_fop_poll,
> >  #ifndef CONFIG_MMU
> > -     .get_unmapped_area = uvc_v4l2_get_unmapped_area,
> > +     .get_unmapped_area = vb2_fop_get_unmapped_area,
> >  #endif
> >  };
> >
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -326,7 +326,10 @@ struct uvc_buffer {
> >
> >  struct uvc_video_queue {
> >       struct vb2_queue queue;
> > -     struct mutex mutex;                     /* Protects queue */
> > +     struct mutex mutex;                     /*
> > +                                              * Serializes vb2_queue and
> > +                                              * fops
> > +                                              */
> >
> >       unsigned int flags;
> >       unsigned int buf_used;
> > @@ -349,7 +352,6 @@ struct uvc_video_chain {
> >                                                * uvc_fh.pending_async_ctrls
> >                                                */
> >
> > -     struct v4l2_prio_state prio;            /* V4L2 priority state */
> >       u32 caps;                               /* V4L2 chain-wide caps */
> >       u8 ctrl_class_bitmap;                   /* Bitmap of valid classes */
> >  };
> > @@ -619,16 +621,10 @@ struct uvc_device {
> >       struct uvc_entity *gpio_unit;
> >  };
> >
> > -enum uvc_handle_state {
> > -     UVC_HANDLE_PASSIVE      = 0,
> > -     UVC_HANDLE_ACTIVE       = 1,
> > -};
> > -
> >  struct uvc_fh {
> >       struct v4l2_fh vfh;
> >       struct uvc_video_chain *chain;
> >       struct uvc_streaming *stream;
> > -     enum uvc_handle_state state;
> >       unsigned int pending_async_ctrls;
> >       bool is_streaming;
> >  };
> > @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> >
> >  /* Video buffers queue management. */
> >  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > -void uvc_queue_release(struct uvc_video_queue *queue);
> > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > -                     struct v4l2_requestbuffers *rb);
> > -int uvc_query_buffer(struct uvc_video_queue *queue,
> > -                  struct v4l2_buffer *v4l2_buf);
> > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > -                    struct v4l2_create_buffers *v4l2_cb);
> > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > -                  struct media_device *mdev,
> > -                  struct v4l2_buffer *v4l2_buf);
> > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > -                   struct v4l2_exportbuffer *exp);
> > -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> > -                    struct v4l2_buffer *v4l2_buf, int nonblocking);
> > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> >  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> >                                        struct uvc_buffer *buf);
> >  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> >  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> > -int uvc_queue_mmap(struct uvc_video_queue *queue,
> > -                struct vm_area_struct *vma);
> > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > -                     poll_table *wait);
> > -#ifndef CONFIG_MMU
> > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > -                                       unsigned long pgoff);
> > -#endif
> > -int uvc_queue_allocated(struct uvc_video_queue *queue);
> >  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> >  {
> >       return vb2_is_streaming(&queue->queue);
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Hans Verkuil]

On 02/06/2025 20:31, Laurent Pinchart wrote:
> Hi Ricardo, Hans,
> 
> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
>> From: Hans Verkuil <hans@jjverkuil.nl>
>>
>> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
>>
>> This patch switches uvc over to those helpers, which removes a lot of
>> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> 
> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> patch does related to priority is replace the per-chain priority
> handling with a per-device (as in uvc_device) priority, as the default
> is to use the prio state from v4l2_device. I think this is actually
> incorrect, a UVC device can have multiple independent streaming
> interfaces, so the priority ioctls should no operate on a device-wide
> prio state. Am I missing something ?

The prio handling is per video_device. So an application that opens
/dev/videoX can raise the priority on the file handle to prevent other
applications that open the same video device from making changes.

> 
>> and allows us
>> to drop the 'privileges' scheme, since that's now handled inside the vb2
>> helpers.
> 
> That part is correct. The driver implements a privilege-management
> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> handlers, as the ioctl handlers didn't exist back then.
> 
> Please reword the commit message to make this clearer. If the prio
> change is also desired, it should be split in a separate patch.
> 
>> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
>>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
>>
>> This patch introduces a change on behavior on the uvcdriver to be
>> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
>> S_FORMAT do no grant exclusive ownership of the device.
> 
> There are other changes in behaviour worth noting, some small, some
> quite substantial. Let's start with the small one: .vidioc_querybuf()
> now succeeds when the queue is busy. It seems a check may be missing in
> v4l2-compliance for this.

It is perfectly fine querying buffers even if the queue is busy, it doesn't
affect streaming.

Regards,

	Hans

> 
> The bigger change is related to locking. See below.
> 
>> Reviewed-by: Hans de Goede <hansg@kernel.org>
>> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
>> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
>> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>> ---
>>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
>>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
>>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
>>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
>>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
>>  5 files changed, 30 insertions(+), 443 deletions(-)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
>> --- a/drivers/media/usb/uvc/uvc_driver.c
>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
>>  	INIT_LIST_HEAD(&chain->entities);
>>  	mutex_init(&chain->ctrl_mutex);
>>  	chain->dev = dev;
>> -	v4l2_prio_init(&chain->prio);
>>  
>>  	return chain;
>>  }
>> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
>>  		if (!video_is_registered(&stream->vdev))
>>  			continue;
>>  
>> -		/*
>> -		 * For stream->vdev we follow the same logic as:
>> -		 * vb2_video_unregister_device().
>> -		 */
>> -
>> -		/* 1. Take a reference to vdev */
>> -		get_device(&stream->vdev.dev);
>> -
>> -		/* 2. Ensure that no new ioctls can be called. */
>> -		video_unregister_device(&stream->vdev);
>> -
>> -		/* 3. Wait for old ioctls to finish. */
>> -		mutex_lock(&stream->mutex);
>> -
>> -		/* 4. Stop streaming. */
>> -		uvc_queue_release(&stream->queue);
>> -
>> -		mutex_unlock(&stream->mutex);
>> -
>> -		put_device(&stream->vdev.dev);
>> -
>> -		/*
>> -		 * For stream->meta.vdev we can directly call:
>> -		 * vb2_video_unregister_device().
>> -		 */
>> +		vb2_video_unregister_device(&stream->vdev);
>>  		vb2_video_unregister_device(&stream->meta.vdev);
>>  
>>  		/*
>> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
>>  	vdev->fops = fops;
>>  	vdev->ioctl_ops = ioctl_ops;
>>  	vdev->release = uvc_release;
>> -	vdev->prio = &stream->chain->prio;
>> +	vdev->queue = &queue->queue;
>> +	vdev->lock = &queue->mutex;
> 
> This will cause the ioctl handlers to use queue->mutex for all ioctls
> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> coarse, that should be mentioned in the commit message.
> 
>>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
>>  		vdev->vfl_dir = VFL_DIR_TX;
>>  	else
>> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
>>  		if (stream->intf == intf) {
>>  			ret = uvc_video_resume(stream, reset);
>>  			if (ret < 0)
>> -				uvc_queue_streamoff(&stream->queue,
>> -						    stream->queue.queue.type);
>> +				vb2_streamoff(&stream->queue.queue,
>> +					      stream->queue.queue.type);
> 
> This doesn't take any lock anymore. Can that be a problem ?
> 
>>  			return ret;
>>  		}
>>  	}
>> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
>> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
>> --- a/drivers/media/usb/uvc/uvc_metadata.c
>> +++ b/drivers/media/usb/uvc/uvc_metadata.c
>> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
>>  	 */
>>  	mutex_lock(&stream->mutex);
> 
> Is this lock still needed ? More broadly speaking, what's the remaining
> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> drop queue->mutex, and use stream->mutex everywhere instead ?
> 
>>  
>> -	if (uvc_queue_allocated(&stream->queue))
>> +	if (vb2_is_busy(&stream->meta.queue.queue))
>>  		ret = -EBUSY;
>>  	else
>>  		stream->meta.format = fmt->dataformat;
>> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
>>  
>>  	stream->meta.format = V4L2_META_FMT_UVC;
>>  
>> -	/*
>> -	 * The video interface queue uses manual locking and thus does not set
>> -	 * the queue pointer. Set it manually here.
>> -	 */
>> -	vdev->queue = &queue->queue;
>> -
>>  	return uvc_register_video_device(dev, stream, vdev, queue,
>>  					 V4L2_BUF_TYPE_META_CAPTURE,
>>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
>> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
>> --- a/drivers/media/usb/uvc/uvc_queue.c
>> +++ b/drivers/media/usb/uvc/uvc_queue.c
>> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>  	return 0;
>>  }
>>  
>> -void uvc_queue_release(struct uvc_video_queue *queue)
>> -{
>> -	mutex_lock(&queue->mutex);
>> -	vb2_queue_release(&queue->queue);
>> -	mutex_unlock(&queue->mutex);
>> -}
>> -
>> -/* -----------------------------------------------------------------------------
>> - * V4L2 queue operations
>> - */
>> -
>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>> -			struct v4l2_requestbuffers *rb)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_reqbufs(&queue->queue, rb);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret ? ret : rb->count;
>> -}
>> -
>> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_querybuf(&queue->queue, buf);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>> -		       struct v4l2_create_buffers *cb)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_create_bufs(&queue->queue, cb);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>> -		     struct media_device *mdev, struct v4l2_buffer *buf)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>> -		      struct v4l2_exportbuffer *exp)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_expbuf(&queue->queue, exp);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
>> -		       int nonblocking)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_streamon(&queue->queue, type);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_streamoff(&queue->queue, type);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
>> -{
>> -	return vb2_mmap(&queue->queue, vma);
>> -}
>> -
>> -#ifndef CONFIG_MMU
>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>> -		unsigned long pgoff)
>> -{
>> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
>> -}
>> -#endif
>> -
>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>> -			    poll_table *wait)
>> -{
>> -	__poll_t ret;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	ret = vb2_poll(&queue->queue, file, wait);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return ret;
>> -}
>> -
>>  /* -----------------------------------------------------------------------------
>>   *
>>   */
>>  
>> -/*
>> - * Check if buffers have been allocated.
>> - */
>> -int uvc_queue_allocated(struct uvc_video_queue *queue)
>> -{
>> -	int allocated;
>> -
>> -	mutex_lock(&queue->mutex);
>> -	allocated = vb2_is_busy(&queue->queue);
>> -	mutex_unlock(&queue->mutex);
>> -
>> -	return allocated;
>> -}
>> -
>>  /*
>>   * Cancel the video buffers queue.
>>   *
>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
>> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
>>  	usb_autopm_put_interface(dev->intf);
>>  }
>>  
>> -static int uvc_acquire_privileges(struct uvc_fh *handle);
>> -
>>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
>>  				      struct uvc_control_mapping *map,
>>  				      const struct uvc_xu_control_mapping *xmap)
>> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>  	const struct uvc_frame *frame;
>>  	int ret;
>>  
>> -	ret = uvc_acquire_privileges(handle);
>> -	if (ret < 0)
>> -		return ret;
>> -
>>  	if (fmt->type != stream->type)
>>  		return -EINVAL;
>>  
>> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>  		return ret;
>>  
>>  	mutex_lock(&stream->mutex);
>> -
>> -	if (uvc_queue_allocated(&stream->queue)) {
>> +	if (vb2_is_busy(&stream->queue.queue)) {
>>  		ret = -EBUSY;
>>  		goto done;
>>  	}
>> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>  	unsigned int i;
>>  	int ret;
>>  
>> -	ret = uvc_acquire_privileges(handle);
>> -	if (ret < 0)
>> -		return ret;
>> -
>>  	if (parm->type != stream->type)
>>  		return -EINVAL;
>>  
>> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>  	return 0;
>>  }
>>  
>> -/* ------------------------------------------------------------------------
>> - * Privilege management
>> - */
>> -
>> -/*
>> - * Privilege management is the multiple-open implementation basis. The current
>> - * implementation is completely transparent for the end-user and doesn't
>> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
>> - * Those ioctls enable finer control on the device (by making possible for a
>> - * user to request exclusive access to a device), but are not mature yet.
>> - * Switching to the V4L2 priority mechanism might be considered in the future
>> - * if this situation changes.
>> - *
>> - * Each open instance of a UVC device can either be in a privileged or
>> - * unprivileged state. Only a single instance can be in a privileged state at
>> - * a given time. Trying to perform an operation that requires privileges will
>> - * automatically acquire the required privileges if possible, or return -EBUSY
>> - * otherwise. Privileges are dismissed when closing the instance or when
>> - * freeing the video buffers using VIDIOC_REQBUFS.
>> - *
>> - * Operations that require privileges are:
>> - *
>> - * - VIDIOC_S_INPUT
>> - * - VIDIOC_S_PARM
>> - * - VIDIOC_S_FMT
>> - * - VIDIOC_CREATE_BUFS
>> - * - VIDIOC_REQBUFS
>> - */
>> -static int uvc_acquire_privileges(struct uvc_fh *handle)
>> -{
>> -	/* Always succeed if the handle is already privileged. */
>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>> -		return 0;
>> -
>> -	/* Check if the device already has a privileged handle. */
>> -	if (atomic_inc_return(&handle->stream->active) != 1) {
>> -		atomic_dec(&handle->stream->active);
>> -		return -EBUSY;
>> -	}
>> -
>> -	handle->state = UVC_HANDLE_ACTIVE;
>> -	return 0;
>> -}
>> -
>> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
>> -{
>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>> -		atomic_dec(&handle->stream->active);
>> -
>> -	handle->state = UVC_HANDLE_PASSIVE;
>> -}
>> -
>> -static int uvc_has_privileges(struct uvc_fh *handle)
>> -{
>> -	return handle->state == UVC_HANDLE_ACTIVE;
>> -}
>> -
>>  /* ------------------------------------------------------------------------
>>   * V4L2 file operations
>>   */
>> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
>>  	v4l2_fh_add(&handle->vfh);
>>  	handle->chain = stream->chain;
>>  	handle->stream = stream;
>> -	handle->state = UVC_HANDLE_PASSIVE;
>>  	file->private_data = handle;
>>  
>>  	return 0;
>> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
>>  
>>  	uvc_ctrl_cleanup_fh(handle);
>>  
>> -	/* Only free resources if this is a privileged handle. */
>> -	if (uvc_has_privileges(handle))
>> -		uvc_queue_release(&stream->queue);
>> -
>>  	if (handle->is_streaming)
>>  		uvc_pm_put(stream->dev);
>>  
>>  	/* Release the file handle. */
>> -	uvc_dismiss_privileges(handle);
>> -	v4l2_fh_del(&handle->vfh);
>> -	v4l2_fh_exit(&handle->vfh);
>> -	kfree(handle);
>> +	vb2_fop_release(file);
>>  	file->private_data = NULL;
> 
> You can drop setting private_data to NULL, it's done by
> v4l2_fh_release() called by vb2_fop_release().
> 
>>  
>>  	return 0;
>> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>>  }
>>  
>> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
>> -			     struct v4l2_requestbuffers *rb)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -	int ret;
>> -
>> -	ret = uvc_acquire_privileges(handle);
>> -	if (ret < 0)
>> -		return ret;
>> -
>> -	mutex_lock(&stream->mutex);
>> -	ret = uvc_request_buffers(&stream->queue, rb);
>> -	mutex_unlock(&stream->mutex);
>> -	if (ret < 0)
>> -		return ret;
>> -
>> -	if (ret == 0)
>> -		uvc_dismiss_privileges(handle);
>> -
>> -	return 0;
>> -}
>> -
>> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
>> -			      struct v4l2_buffer *buf)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	return uvc_query_buffer(&stream->queue, buf);
>> -}
>> -
>> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	return uvc_queue_buffer(&stream->queue,
>> -				stream->vdev.v4l2_dev->mdev, buf);
>> -}
>> -
>> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
>> -			    struct v4l2_exportbuffer *exp)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	return uvc_export_buffer(&stream->queue, exp);
>> -}
>> -
>> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	return uvc_dequeue_buffer(&stream->queue, buf,
>> -				  file->f_flags & O_NONBLOCK);
>> -}
>> -
>> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
>> -				  struct v4l2_create_buffers *cb)
>> -{
>> -	struct uvc_fh *handle = fh;
>> -	struct uvc_streaming *stream = handle->stream;
>> -	int ret;
>> -
>> -	ret = uvc_acquire_privileges(handle);
>> -	if (ret < 0)
>> -		return ret;
>> -
>> -	return uvc_create_buffers(&stream->queue, cb);
>> -}
>> -
>>  static int uvc_ioctl_streamon(struct file *file, void *fh,
>>  			      enum v4l2_buf_type type)
>>  {
>> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>  	struct uvc_streaming *stream = handle->stream;
>>  	int ret;
>>  
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	guard(mutex)(&stream->mutex);
>> -
>>  	if (handle->is_streaming)
>>  		return 0;
>>  
>> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>  	if (ret)
>>  		return ret;
>>  
>> -	ret = uvc_queue_streamon(&stream->queue, type);
>> +	ret = vb2_ioctl_streamon(file, fh, type);
>>  	if (ret) {
>>  		uvc_pm_put(stream->dev);
>>  		return ret;
>> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
>>  {
>>  	struct uvc_fh *handle = fh;
>>  	struct uvc_streaming *stream = handle->stream;
>> +	int ret;
>>  
>> -	if (!uvc_has_privileges(handle))
>> -		return -EBUSY;
>> -
>> -	guard(mutex)(&stream->mutex);
>> +	ret = vb2_ioctl_streamoff(file, fh, type);
>> +	if (ret)
>> +		return ret;
>>  
>> -	uvc_queue_streamoff(&stream->queue, type);
>>  	if (handle->is_streaming) {
>>  		handle->is_streaming = false;
>>  		uvc_pm_put(stream->dev);
>> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
>>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
>>  {
>>  	struct uvc_fh *handle = fh;
>> +	struct uvc_streaming *stream = handle->stream;
>>  	struct uvc_video_chain *chain = handle->chain;
>>  	u8 *buf;
>>  	int ret;
>>  
>> -	ret = uvc_acquire_privileges(handle);
>> -	if (ret < 0)
>> -		return ret;
>> +	if (vb2_is_busy(&stream->queue.queue))
>> +		return -EBUSY;
>>  
>>  	if (chain->selector == NULL ||
>>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
>> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>>  	return ret;
>>  }
>>  
>> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
>> -		    size_t count, loff_t *ppos)
>> -{
>> -	struct uvc_fh *handle = file->private_data;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
>> -	return -EINVAL;
>> -}
>> -
>> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
>> -{
>> -	struct uvc_fh *handle = file->private_data;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>> -
>> -	return uvc_queue_mmap(&stream->queue, vma);
>> -}
>> -
>> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
>> -{
>> -	struct uvc_fh *handle = file->private_data;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>> -
>> -	return uvc_queue_poll(&stream->queue, file, wait);
>> -}
>> -
>> -#ifndef CONFIG_MMU
>> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
>> -		unsigned long addr, unsigned long len, unsigned long pgoff,
>> -		unsigned long flags)
>> -{
>> -	struct uvc_fh *handle = file->private_data;
>> -	struct uvc_streaming *stream = handle->stream;
>> -
>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>> -
>> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
>> -}
>> -#endif
>> -
>>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
>>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
>>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
>> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
>> -	.vidioc_querybuf = uvc_ioctl_querybuf,
>> -	.vidioc_qbuf = uvc_ioctl_qbuf,
>> -	.vidioc_expbuf = uvc_ioctl_expbuf,
>> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
>> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>>  	.vidioc_streamon = uvc_ioctl_streamon,
>>  	.vidioc_streamoff = uvc_ioctl_streamoff,
>>  	.vidioc_enum_input = uvc_ioctl_enum_input,
>> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
>>  #ifdef CONFIG_COMPAT
>>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
>>  #endif
>> -	.read		= uvc_v4l2_read,
>> -	.mmap		= uvc_v4l2_mmap,
>> -	.poll		= uvc_v4l2_poll,
>> +	.mmap		= vb2_fop_mmap,
>> +	.poll		= vb2_fop_poll,
>>  #ifndef CONFIG_MMU
>> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
>> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
>>  #endif
>>  };
>>  
>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
>> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
>> --- a/drivers/media/usb/uvc/uvcvideo.h
>> +++ b/drivers/media/usb/uvc/uvcvideo.h
>> @@ -326,7 +326,10 @@ struct uvc_buffer {
>>  
>>  struct uvc_video_queue {
>>  	struct vb2_queue queue;
>> -	struct mutex mutex;			/* Protects queue */
>> +	struct mutex mutex;			/*
>> +						 * Serializes vb2_queue and
>> +						 * fops
>> +						 */
>>  
>>  	unsigned int flags;
>>  	unsigned int buf_used;
>> @@ -349,7 +352,6 @@ struct uvc_video_chain {
>>  						 * uvc_fh.pending_async_ctrls
>>  						 */
>>  
>> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
>>  	u32 caps;				/* V4L2 chain-wide caps */
>>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
>>  };
>> @@ -619,16 +621,10 @@ struct uvc_device {
>>  	struct uvc_entity *gpio_unit;
>>  };
>>  
>> -enum uvc_handle_state {
>> -	UVC_HANDLE_PASSIVE	= 0,
>> -	UVC_HANDLE_ACTIVE	= 1,
>> -};
>> -
>>  struct uvc_fh {
>>  	struct v4l2_fh vfh;
>>  	struct uvc_video_chain *chain;
>>  	struct uvc_streaming *stream;
>> -	enum uvc_handle_state state;
>>  	unsigned int pending_async_ctrls;
>>  	bool is_streaming;
>>  };
>> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>>  
>>  /* Video buffers queue management. */
>>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>> -void uvc_queue_release(struct uvc_video_queue *queue);
>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>> -			struct v4l2_requestbuffers *rb);
>> -int uvc_query_buffer(struct uvc_video_queue *queue,
>> -		     struct v4l2_buffer *v4l2_buf);
>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>> -		       struct v4l2_create_buffers *v4l2_cb);
>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>> -		     struct media_device *mdev,
>> -		     struct v4l2_buffer *v4l2_buf);
>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>> -		      struct v4l2_exportbuffer *exp);
>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
>> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>>  					 struct uvc_buffer *buf);
>>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
>>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
>> -int uvc_queue_mmap(struct uvc_video_queue *queue,
>> -		   struct vm_area_struct *vma);
>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>> -			poll_table *wait);
>> -#ifndef CONFIG_MMU
>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>> -					  unsigned long pgoff);
>> -#endif
>> -int uvc_queue_allocated(struct uvc_video_queue *queue);
>>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>>  {
>>  	return vb2_is_streaming(&queue->queue);
> 

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Hans Verkuil]

On 02/06/2025 21:58, Hans Verkuil wrote:
> On 02/06/2025 20:31, Laurent Pinchart wrote:
>> Hi Ricardo, Hans,
>>
>> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
>>> From: Hans Verkuil <hans@jjverkuil.nl>
>>>
>>> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
>>>
>>> This patch switches uvc over to those helpers, which removes a lot of
>>> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
>>
>> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
>> patch does related to priority is replace the per-chain priority
>> handling with a per-device (as in uvc_device) priority, as the default
>> is to use the prio state from v4l2_device. I think this is actually
>> incorrect, a UVC device can have multiple independent streaming
>> interfaces, so the priority ioctls should no operate on a device-wide
>> prio state. Am I missing something ?
> 
> The prio handling is per video_device. So an application that opens
> /dev/videoX can raise the priority on the file handle to prevent other
> applications that open the same video device from making changes.

Sorry, ignore that reply. I hadn't noticed that vdev->prio was set to
the per-chain prio.

I'm not sure why I dropped that in my original patch. It certainly should
be split off, but probably just dropped, unless v4l2-compliance complains
about it. But in that case, perhaps v4l2-compliance needs to be changed.

To be honest, I haven't paid attention to priorities for many, many years,
so I would have to dig more into this.

For now I agree that this prio change doesn't belong in this patch.

Regards,

	Hans

> 
>>
>>> and allows us
>>> to drop the 'privileges' scheme, since that's now handled inside the vb2
>>> helpers.
>>
>> That part is correct. The driver implements a privilege-management
>> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
>> handlers, as the ioctl handlers didn't exist back then.
>>
>> Please reword the commit message to make this clearer. If the prio
>> change is also desired, it should be split in a separate patch.
>>
>>> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
>>>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
>>>
>>> This patch introduces a change on behavior on the uvcdriver to be
>>> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
>>> S_FORMAT do no grant exclusive ownership of the device.
>>
>> There are other changes in behaviour worth noting, some small, some
>> quite substantial. Let's start with the small one: .vidioc_querybuf()
>> now succeeds when the queue is busy. It seems a check may be missing in
>> v4l2-compliance for this.
> 
> It is perfectly fine querying buffers even if the queue is busy, it doesn't
> affect streaming.
> 
> Regards,
> 
> 	Hans
> 
>>
>> The bigger change is related to locking. See below.
>>
>>> Reviewed-by: Hans de Goede <hansg@kernel.org>
>>> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
>>> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
>>> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
>>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>>> ---
>>>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
>>>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
>>>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
>>>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
>>>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
>>>  5 files changed, 30 insertions(+), 443 deletions(-)
>>>
>>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>>> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
>>> --- a/drivers/media/usb/uvc/uvc_driver.c
>>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>>> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
>>>  	INIT_LIST_HEAD(&chain->entities);
>>>  	mutex_init(&chain->ctrl_mutex);
>>>  	chain->dev = dev;
>>> -	v4l2_prio_init(&chain->prio);
>>>  
>>>  	return chain;
>>>  }
>>> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
>>>  		if (!video_is_registered(&stream->vdev))
>>>  			continue;
>>>  
>>> -		/*
>>> -		 * For stream->vdev we follow the same logic as:
>>> -		 * vb2_video_unregister_device().
>>> -		 */
>>> -
>>> -		/* 1. Take a reference to vdev */
>>> -		get_device(&stream->vdev.dev);
>>> -
>>> -		/* 2. Ensure that no new ioctls can be called. */
>>> -		video_unregister_device(&stream->vdev);
>>> -
>>> -		/* 3. Wait for old ioctls to finish. */
>>> -		mutex_lock(&stream->mutex);
>>> -
>>> -		/* 4. Stop streaming. */
>>> -		uvc_queue_release(&stream->queue);
>>> -
>>> -		mutex_unlock(&stream->mutex);
>>> -
>>> -		put_device(&stream->vdev.dev);
>>> -
>>> -		/*
>>> -		 * For stream->meta.vdev we can directly call:
>>> -		 * vb2_video_unregister_device().
>>> -		 */
>>> +		vb2_video_unregister_device(&stream->vdev);
>>>  		vb2_video_unregister_device(&stream->meta.vdev);
>>>  
>>>  		/*
>>> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
>>>  	vdev->fops = fops;
>>>  	vdev->ioctl_ops = ioctl_ops;
>>>  	vdev->release = uvc_release;
>>> -	vdev->prio = &stream->chain->prio;
>>> +	vdev->queue = &queue->queue;
>>> +	vdev->lock = &queue->mutex;
>>
>> This will cause the ioctl handlers to use queue->mutex for all ioctls
>> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
>> coarse, that should be mentioned in the commit message.
>>
>>>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
>>>  		vdev->vfl_dir = VFL_DIR_TX;
>>>  	else
>>> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
>>>  		if (stream->intf == intf) {
>>>  			ret = uvc_video_resume(stream, reset);
>>>  			if (ret < 0)
>>> -				uvc_queue_streamoff(&stream->queue,
>>> -						    stream->queue.queue.type);
>>> +				vb2_streamoff(&stream->queue.queue,
>>> +					      stream->queue.queue.type);
>>
>> This doesn't take any lock anymore. Can that be a problem ?
>>
>>>  			return ret;
>>>  		}
>>>  	}
>>> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
>>> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
>>> --- a/drivers/media/usb/uvc/uvc_metadata.c
>>> +++ b/drivers/media/usb/uvc/uvc_metadata.c
>>> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
>>>  	 */
>>>  	mutex_lock(&stream->mutex);
>>
>> Is this lock still needed ? More broadly speaking, what's the remaining
>> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
>> drop queue->mutex, and use stream->mutex everywhere instead ?
>>
>>>  
>>> -	if (uvc_queue_allocated(&stream->queue))
>>> +	if (vb2_is_busy(&stream->meta.queue.queue))
>>>  		ret = -EBUSY;
>>>  	else
>>>  		stream->meta.format = fmt->dataformat;
>>> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
>>>  
>>>  	stream->meta.format = V4L2_META_FMT_UVC;
>>>  
>>> -	/*
>>> -	 * The video interface queue uses manual locking and thus does not set
>>> -	 * the queue pointer. Set it manually here.
>>> -	 */
>>> -	vdev->queue = &queue->queue;
>>> -
>>>  	return uvc_register_video_device(dev, stream, vdev, queue,
>>>  					 V4L2_BUF_TYPE_META_CAPTURE,
>>>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
>>> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
>>> --- a/drivers/media/usb/uvc/uvc_queue.c
>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
>>> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>  	return 0;
>>>  }
>>>  
>>> -void uvc_queue_release(struct uvc_video_queue *queue)
>>> -{
>>> -	mutex_lock(&queue->mutex);
>>> -	vb2_queue_release(&queue->queue);
>>> -	mutex_unlock(&queue->mutex);
>>> -}
>>> -
>>> -/* -----------------------------------------------------------------------------
>>> - * V4L2 queue operations
>>> - */
>>> -
>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>> -			struct v4l2_requestbuffers *rb)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_reqbufs(&queue->queue, rb);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret ? ret : rb->count;
>>> -}
>>> -
>>> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_querybuf(&queue->queue, buf);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>> -		       struct v4l2_create_buffers *cb)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_create_bufs(&queue->queue, cb);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>> -		     struct media_device *mdev, struct v4l2_buffer *buf)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>> -		      struct v4l2_exportbuffer *exp)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_expbuf(&queue->queue, exp);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
>>> -		       int nonblocking)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_streamon(&queue->queue, type);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>> -{
>>> -	int ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_streamoff(&queue->queue, type);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
>>> -{
>>> -	return vb2_mmap(&queue->queue, vma);
>>> -}
>>> -
>>> -#ifndef CONFIG_MMU
>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>> -		unsigned long pgoff)
>>> -{
>>> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
>>> -}
>>> -#endif
>>> -
>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>> -			    poll_table *wait)
>>> -{
>>> -	__poll_t ret;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	ret = vb2_poll(&queue->queue, file, wait);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return ret;
>>> -}
>>> -
>>>  /* -----------------------------------------------------------------------------
>>>   *
>>>   */
>>>  
>>> -/*
>>> - * Check if buffers have been allocated.
>>> - */
>>> -int uvc_queue_allocated(struct uvc_video_queue *queue)
>>> -{
>>> -	int allocated;
>>> -
>>> -	mutex_lock(&queue->mutex);
>>> -	allocated = vb2_is_busy(&queue->queue);
>>> -	mutex_unlock(&queue->mutex);
>>> -
>>> -	return allocated;
>>> -}
>>> -
>>>  /*
>>>   * Cancel the video buffers queue.
>>>   *
>>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
>>> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
>>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>>> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
>>>  	usb_autopm_put_interface(dev->intf);
>>>  }
>>>  
>>> -static int uvc_acquire_privileges(struct uvc_fh *handle);
>>> -
>>>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
>>>  				      struct uvc_control_mapping *map,
>>>  				      const struct uvc_xu_control_mapping *xmap)
>>> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>  	const struct uvc_frame *frame;
>>>  	int ret;
>>>  
>>> -	ret = uvc_acquire_privileges(handle);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -
>>>  	if (fmt->type != stream->type)
>>>  		return -EINVAL;
>>>  
>>> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>  		return ret;
>>>  
>>>  	mutex_lock(&stream->mutex);
>>> -
>>> -	if (uvc_queue_allocated(&stream->queue)) {
>>> +	if (vb2_is_busy(&stream->queue.queue)) {
>>>  		ret = -EBUSY;
>>>  		goto done;
>>>  	}
>>> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>  	unsigned int i;
>>>  	int ret;
>>>  
>>> -	ret = uvc_acquire_privileges(handle);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -
>>>  	if (parm->type != stream->type)
>>>  		return -EINVAL;
>>>  
>>> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>  	return 0;
>>>  }
>>>  
>>> -/* ------------------------------------------------------------------------
>>> - * Privilege management
>>> - */
>>> -
>>> -/*
>>> - * Privilege management is the multiple-open implementation basis. The current
>>> - * implementation is completely transparent for the end-user and doesn't
>>> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
>>> - * Those ioctls enable finer control on the device (by making possible for a
>>> - * user to request exclusive access to a device), but are not mature yet.
>>> - * Switching to the V4L2 priority mechanism might be considered in the future
>>> - * if this situation changes.
>>> - *
>>> - * Each open instance of a UVC device can either be in a privileged or
>>> - * unprivileged state. Only a single instance can be in a privileged state at
>>> - * a given time. Trying to perform an operation that requires privileges will
>>> - * automatically acquire the required privileges if possible, or return -EBUSY
>>> - * otherwise. Privileges are dismissed when closing the instance or when
>>> - * freeing the video buffers using VIDIOC_REQBUFS.
>>> - *
>>> - * Operations that require privileges are:
>>> - *
>>> - * - VIDIOC_S_INPUT
>>> - * - VIDIOC_S_PARM
>>> - * - VIDIOC_S_FMT
>>> - * - VIDIOC_CREATE_BUFS
>>> - * - VIDIOC_REQBUFS
>>> - */
>>> -static int uvc_acquire_privileges(struct uvc_fh *handle)
>>> -{
>>> -	/* Always succeed if the handle is already privileged. */
>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>> -		return 0;
>>> -
>>> -	/* Check if the device already has a privileged handle. */
>>> -	if (atomic_inc_return(&handle->stream->active) != 1) {
>>> -		atomic_dec(&handle->stream->active);
>>> -		return -EBUSY;
>>> -	}
>>> -
>>> -	handle->state = UVC_HANDLE_ACTIVE;
>>> -	return 0;
>>> -}
>>> -
>>> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
>>> -{
>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>> -		atomic_dec(&handle->stream->active);
>>> -
>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>> -}
>>> -
>>> -static int uvc_has_privileges(struct uvc_fh *handle)
>>> -{
>>> -	return handle->state == UVC_HANDLE_ACTIVE;
>>> -}
>>> -
>>>  /* ------------------------------------------------------------------------
>>>   * V4L2 file operations
>>>   */
>>> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
>>>  	v4l2_fh_add(&handle->vfh);
>>>  	handle->chain = stream->chain;
>>>  	handle->stream = stream;
>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>>  	file->private_data = handle;
>>>  
>>>  	return 0;
>>> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
>>>  
>>>  	uvc_ctrl_cleanup_fh(handle);
>>>  
>>> -	/* Only free resources if this is a privileged handle. */
>>> -	if (uvc_has_privileges(handle))
>>> -		uvc_queue_release(&stream->queue);
>>> -
>>>  	if (handle->is_streaming)
>>>  		uvc_pm_put(stream->dev);
>>>  
>>>  	/* Release the file handle. */
>>> -	uvc_dismiss_privileges(handle);
>>> -	v4l2_fh_del(&handle->vfh);
>>> -	v4l2_fh_exit(&handle->vfh);
>>> -	kfree(handle);
>>> +	vb2_fop_release(file);
>>>  	file->private_data = NULL;
>>
>> You can drop setting private_data to NULL, it's done by
>> v4l2_fh_release() called by vb2_fop_release().
>>
>>>  
>>>  	return 0;
>>> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>>>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>>>  }
>>>  
>>> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
>>> -			     struct v4l2_requestbuffers *rb)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -	int ret;
>>> -
>>> -	ret = uvc_acquire_privileges(handle);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -
>>> -	mutex_lock(&stream->mutex);
>>> -	ret = uvc_request_buffers(&stream->queue, rb);
>>> -	mutex_unlock(&stream->mutex);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -
>>> -	if (ret == 0)
>>> -		uvc_dismiss_privileges(handle);
>>> -
>>> -	return 0;
>>> -}
>>> -
>>> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
>>> -			      struct v4l2_buffer *buf)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	return uvc_query_buffer(&stream->queue, buf);
>>> -}
>>> -
>>> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	return uvc_queue_buffer(&stream->queue,
>>> -				stream->vdev.v4l2_dev->mdev, buf);
>>> -}
>>> -
>>> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
>>> -			    struct v4l2_exportbuffer *exp)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	return uvc_export_buffer(&stream->queue, exp);
>>> -}
>>> -
>>> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	return uvc_dequeue_buffer(&stream->queue, buf,
>>> -				  file->f_flags & O_NONBLOCK);
>>> -}
>>> -
>>> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
>>> -				  struct v4l2_create_buffers *cb)
>>> -{
>>> -	struct uvc_fh *handle = fh;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -	int ret;
>>> -
>>> -	ret = uvc_acquire_privileges(handle);
>>> -	if (ret < 0)
>>> -		return ret;
>>> -
>>> -	return uvc_create_buffers(&stream->queue, cb);
>>> -}
>>> -
>>>  static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>  			      enum v4l2_buf_type type)
>>>  {
>>> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>  	struct uvc_streaming *stream = handle->stream;
>>>  	int ret;
>>>  
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	guard(mutex)(&stream->mutex);
>>> -
>>>  	if (handle->is_streaming)
>>>  		return 0;
>>>  
>>> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>  	if (ret)
>>>  		return ret;
>>>  
>>> -	ret = uvc_queue_streamon(&stream->queue, type);
>>> +	ret = vb2_ioctl_streamon(file, fh, type);
>>>  	if (ret) {
>>>  		uvc_pm_put(stream->dev);
>>>  		return ret;
>>> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
>>>  {
>>>  	struct uvc_fh *handle = fh;
>>>  	struct uvc_streaming *stream = handle->stream;
>>> +	int ret;
>>>  
>>> -	if (!uvc_has_privileges(handle))
>>> -		return -EBUSY;
>>> -
>>> -	guard(mutex)(&stream->mutex);
>>> +	ret = vb2_ioctl_streamoff(file, fh, type);
>>> +	if (ret)
>>> +		return ret;
>>>  
>>> -	uvc_queue_streamoff(&stream->queue, type);
>>>  	if (handle->is_streaming) {
>>>  		handle->is_streaming = false;
>>>  		uvc_pm_put(stream->dev);
>>> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
>>>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
>>>  {
>>>  	struct uvc_fh *handle = fh;
>>> +	struct uvc_streaming *stream = handle->stream;
>>>  	struct uvc_video_chain *chain = handle->chain;
>>>  	u8 *buf;
>>>  	int ret;
>>>  
>>> -	ret = uvc_acquire_privileges(handle);
>>> -	if (ret < 0)
>>> -		return ret;
>>> +	if (vb2_is_busy(&stream->queue.queue))
>>> +		return -EBUSY;
>>>  
>>>  	if (chain->selector == NULL ||
>>>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
>>> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>>>  	return ret;
>>>  }
>>>  
>>> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
>>> -		    size_t count, loff_t *ppos)
>>> -{
>>> -	struct uvc_fh *handle = file->private_data;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
>>> -	return -EINVAL;
>>> -}
>>> -
>>> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
>>> -{
>>> -	struct uvc_fh *handle = file->private_data;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>> -
>>> -	return uvc_queue_mmap(&stream->queue, vma);
>>> -}
>>> -
>>> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
>>> -{
>>> -	struct uvc_fh *handle = file->private_data;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>> -
>>> -	return uvc_queue_poll(&stream->queue, file, wait);
>>> -}
>>> -
>>> -#ifndef CONFIG_MMU
>>> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
>>> -		unsigned long addr, unsigned long len, unsigned long pgoff,
>>> -		unsigned long flags)
>>> -{
>>> -	struct uvc_fh *handle = file->private_data;
>>> -	struct uvc_streaming *stream = handle->stream;
>>> -
>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>> -
>>> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
>>> -}
>>> -#endif
>>> -
>>>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>>>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>>> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
>>>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
>>>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
>>> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
>>> -	.vidioc_querybuf = uvc_ioctl_querybuf,
>>> -	.vidioc_qbuf = uvc_ioctl_qbuf,
>>> -	.vidioc_expbuf = uvc_ioctl_expbuf,
>>> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
>>> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
>>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
>>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>>>  	.vidioc_streamon = uvc_ioctl_streamon,
>>>  	.vidioc_streamoff = uvc_ioctl_streamoff,
>>>  	.vidioc_enum_input = uvc_ioctl_enum_input,
>>> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
>>>  #ifdef CONFIG_COMPAT
>>>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
>>>  #endif
>>> -	.read		= uvc_v4l2_read,
>>> -	.mmap		= uvc_v4l2_mmap,
>>> -	.poll		= uvc_v4l2_poll,
>>> +	.mmap		= vb2_fop_mmap,
>>> +	.poll		= vb2_fop_poll,
>>>  #ifndef CONFIG_MMU
>>> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
>>> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
>>>  #endif
>>>  };
>>>  
>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
>>> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
>>> --- a/drivers/media/usb/uvc/uvcvideo.h
>>> +++ b/drivers/media/usb/uvc/uvcvideo.h
>>> @@ -326,7 +326,10 @@ struct uvc_buffer {
>>>  
>>>  struct uvc_video_queue {
>>>  	struct vb2_queue queue;
>>> -	struct mutex mutex;			/* Protects queue */
>>> +	struct mutex mutex;			/*
>>> +						 * Serializes vb2_queue and
>>> +						 * fops
>>> +						 */
>>>  
>>>  	unsigned int flags;
>>>  	unsigned int buf_used;
>>> @@ -349,7 +352,6 @@ struct uvc_video_chain {
>>>  						 * uvc_fh.pending_async_ctrls
>>>  						 */
>>>  
>>> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
>>>  	u32 caps;				/* V4L2 chain-wide caps */
>>>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
>>>  };
>>> @@ -619,16 +621,10 @@ struct uvc_device {
>>>  	struct uvc_entity *gpio_unit;
>>>  };
>>>  
>>> -enum uvc_handle_state {
>>> -	UVC_HANDLE_PASSIVE	= 0,
>>> -	UVC_HANDLE_ACTIVE	= 1,
>>> -};
>>> -
>>>  struct uvc_fh {
>>>  	struct v4l2_fh vfh;
>>>  	struct uvc_video_chain *chain;
>>>  	struct uvc_streaming *stream;
>>> -	enum uvc_handle_state state;
>>>  	unsigned int pending_async_ctrls;
>>>  	bool is_streaming;
>>>  };
>>> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>>>  
>>>  /* Video buffers queue management. */
>>>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>> -void uvc_queue_release(struct uvc_video_queue *queue);
>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>> -			struct v4l2_requestbuffers *rb);
>>> -int uvc_query_buffer(struct uvc_video_queue *queue,
>>> -		     struct v4l2_buffer *v4l2_buf);
>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>> -		       struct v4l2_create_buffers *v4l2_cb);
>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>> -		     struct media_device *mdev,
>>> -		     struct v4l2_buffer *v4l2_buf);
>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>> -		      struct v4l2_exportbuffer *exp);
>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
>>> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>>>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>>>  					 struct uvc_buffer *buf);
>>>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
>>>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
>>> -int uvc_queue_mmap(struct uvc_video_queue *queue,
>>> -		   struct vm_area_struct *vma);
>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>> -			poll_table *wait);
>>> -#ifndef CONFIG_MMU
>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>> -					  unsigned long pgoff);
>>> -#endif
>>> -int uvc_queue_allocated(struct uvc_video_queue *queue);
>>>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>>>  {
>>>  	return vb2_is_streaming(&queue->queue);
>>
> 

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Laurent Pinchart]

Hi Hans,

On Mon, Jun 02, 2025 at 09:58:08PM +0200, Hans Verkuil wrote:
> On 02/06/2025 20:31, Laurent Pinchart wrote:
> > On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> >> From: Hans Verkuil <hans@jjverkuil.nl>
> >>
> >> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> >>
> >> This patch switches uvc over to those helpers, which removes a lot of
> >> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> > 
> > How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> > patch does related to priority is replace the per-chain priority
> > handling with a per-device (as in uvc_device) priority, as the default
> > is to use the prio state from v4l2_device. I think this is actually
> > incorrect, a UVC device can have multiple independent streaming
> > interfaces, so the priority ioctls should no operate on a device-wide
> > prio state. Am I missing something ?
> 
> The prio handling is per video_device. So an application that opens
> /dev/videoX can raise the priority on the file handle to prevent other
> applications that open the same video device from making changes.
> 
> >> and allows us
> >> to drop the 'privileges' scheme, since that's now handled inside the vb2
> >> helpers.
> > 
> > That part is correct. The driver implements a privilege-management
> > system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> > handlers, as the ioctl handlers didn't exist back then.
> > 
> > Please reword the commit message to make this clearer. If the prio
> > change is also desired, it should be split in a separate patch.
> > 
> >> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> >>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> >>
> >> This patch introduces a change on behavior on the uvcdriver to be
> >> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> >> S_FORMAT do no grant exclusive ownership of the device.
> > 
> > There are other changes in behaviour worth noting, some small, some
> > quite substantial. Let's start with the small one: .vidioc_querybuf()
> > now succeeds when the queue is busy. It seems a check may be missing in
> > v4l2-compliance for this.
> 
> It is perfectly fine querying buffers even if the queue is busy, it doesn't
> affect streaming.

I agree, and I'm fine with the change in behaviour (as long as it gets
mentioned in the commit message). My point is that the uvcvideo driver
didn't allow it, and that wasn't caught by v4l2-compliance, so we're
probably missing a test there.

> > The bigger change is related to locking. See below.
> > 
> >> Reviewed-by: Hans de Goede <hansg@kernel.org>
> >> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> >> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> >> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> >> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> >> ---
> >>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> >>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> >>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> >>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> >>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> >>  5 files changed, 30 insertions(+), 443 deletions(-)
> >>
> >> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> >> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> >> --- a/drivers/media/usb/uvc/uvc_driver.c
> >> +++ b/drivers/media/usb/uvc/uvc_driver.c
> >> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> >>  	INIT_LIST_HEAD(&chain->entities);
> >>  	mutex_init(&chain->ctrl_mutex);
> >>  	chain->dev = dev;
> >> -	v4l2_prio_init(&chain->prio);
> >>  
> >>  	return chain;
> >>  }
> >> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> >>  		if (!video_is_registered(&stream->vdev))
> >>  			continue;
> >>  
> >> -		/*
> >> -		 * For stream->vdev we follow the same logic as:
> >> -		 * vb2_video_unregister_device().
> >> -		 */
> >> -
> >> -		/* 1. Take a reference to vdev */
> >> -		get_device(&stream->vdev.dev);
> >> -
> >> -		/* 2. Ensure that no new ioctls can be called. */
> >> -		video_unregister_device(&stream->vdev);
> >> -
> >> -		/* 3. Wait for old ioctls to finish. */
> >> -		mutex_lock(&stream->mutex);
> >> -
> >> -		/* 4. Stop streaming. */
> >> -		uvc_queue_release(&stream->queue);
> >> -
> >> -		mutex_unlock(&stream->mutex);
> >> -
> >> -		put_device(&stream->vdev.dev);
> >> -
> >> -		/*
> >> -		 * For stream->meta.vdev we can directly call:
> >> -		 * vb2_video_unregister_device().
> >> -		 */
> >> +		vb2_video_unregister_device(&stream->vdev);
> >>  		vb2_video_unregister_device(&stream->meta.vdev);
> >>  
> >>  		/*
> >> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> >>  	vdev->fops = fops;
> >>  	vdev->ioctl_ops = ioctl_ops;
> >>  	vdev->release = uvc_release;
> >> -	vdev->prio = &stream->chain->prio;
> >> +	vdev->queue = &queue->queue;
> >> +	vdev->lock = &queue->mutex;
> > 
> > This will cause the ioctl handlers to use queue->mutex for all ioctls
> > (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> > coarse, that should be mentioned in the commit message.
> > 
> >>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> >>  		vdev->vfl_dir = VFL_DIR_TX;
> >>  	else
> >> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> >>  		if (stream->intf == intf) {
> >>  			ret = uvc_video_resume(stream, reset);
> >>  			if (ret < 0)
> >> -				uvc_queue_streamoff(&stream->queue,
> >> -						    stream->queue.queue.type);
> >> +				vb2_streamoff(&stream->queue.queue,
> >> +					      stream->queue.queue.type);
> > 
> > This doesn't take any lock anymore. Can that be a problem ?
> > 
> >>  			return ret;
> >>  		}
> >>  	}
> >> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> >> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> >> --- a/drivers/media/usb/uvc/uvc_metadata.c
> >> +++ b/drivers/media/usb/uvc/uvc_metadata.c
> >> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> >>  	 */
> >>  	mutex_lock(&stream->mutex);
> > 
> > Is this lock still needed ? More broadly speaking, what's the remaining
> > purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> > drop queue->mutex, and use stream->mutex everywhere instead ?
> > 
> >>  
> >> -	if (uvc_queue_allocated(&stream->queue))
> >> +	if (vb2_is_busy(&stream->meta.queue.queue))
> >>  		ret = -EBUSY;
> >>  	else
> >>  		stream->meta.format = fmt->dataformat;
> >> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> >>  
> >>  	stream->meta.format = V4L2_META_FMT_UVC;
> >>  
> >> -	/*
> >> -	 * The video interface queue uses manual locking and thus does not set
> >> -	 * the queue pointer. Set it manually here.
> >> -	 */
> >> -	vdev->queue = &queue->queue;
> >> -
> >>  	return uvc_register_video_device(dev, stream, vdev, queue,
> >>  					 V4L2_BUF_TYPE_META_CAPTURE,
> >>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
> >> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> >> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> >> --- a/drivers/media/usb/uvc/uvc_queue.c
> >> +++ b/drivers/media/usb/uvc/uvc_queue.c
> >> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >>  	return 0;
> >>  }
> >>  
> >> -void uvc_queue_release(struct uvc_video_queue *queue)
> >> -{
> >> -	mutex_lock(&queue->mutex);
> >> -	vb2_queue_release(&queue->queue);
> >> -	mutex_unlock(&queue->mutex);
> >> -}
> >> -
> >> -/* -----------------------------------------------------------------------------
> >> - * V4L2 queue operations
> >> - */
> >> -
> >> -int uvc_request_buffers(struct uvc_video_queue *queue,
> >> -			struct v4l2_requestbuffers *rb)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_reqbufs(&queue->queue, rb);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret ? ret : rb->count;
> >> -}
> >> -
> >> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_querybuf(&queue->queue, buf);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_create_buffers(struct uvc_video_queue *queue,
> >> -		       struct v4l2_create_buffers *cb)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_create_bufs(&queue->queue, cb);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> >> -		     struct media_device *mdev, struct v4l2_buffer *buf)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_export_buffer(struct uvc_video_queue *queue,
> >> -		      struct v4l2_exportbuffer *exp)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_expbuf(&queue->queue, exp);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> >> -		       int nonblocking)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_streamon(&queue->queue, type);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >> -{
> >> -	int ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_streamoff(&queue->queue, type);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> >> -{
> >> -	return vb2_mmap(&queue->queue, vma);
> >> -}
> >> -
> >> -#ifndef CONFIG_MMU
> >> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> >> -		unsigned long pgoff)
> >> -{
> >> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> >> -}
> >> -#endif
> >> -
> >> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> >> -			    poll_table *wait)
> >> -{
> >> -	__poll_t ret;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	ret = vb2_poll(&queue->queue, file, wait);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return ret;
> >> -}
> >> -
> >>  /* -----------------------------------------------------------------------------
> >>   *
> >>   */
> >>  
> >> -/*
> >> - * Check if buffers have been allocated.
> >> - */
> >> -int uvc_queue_allocated(struct uvc_video_queue *queue)
> >> -{
> >> -	int allocated;
> >> -
> >> -	mutex_lock(&queue->mutex);
> >> -	allocated = vb2_is_busy(&queue->queue);
> >> -	mutex_unlock(&queue->mutex);
> >> -
> >> -	return allocated;
> >> -}
> >> -
> >>  /*
> >>   * Cancel the video buffers queue.
> >>   *
> >> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> >> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> >> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> >> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> >> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> >>  	usb_autopm_put_interface(dev->intf);
> >>  }
> >>  
> >> -static int uvc_acquire_privileges(struct uvc_fh *handle);
> >> -
> >>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> >>  				      struct uvc_control_mapping *map,
> >>  				      const struct uvc_xu_control_mapping *xmap)
> >> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >>  	const struct uvc_frame *frame;
> >>  	int ret;
> >>  
> >> -	ret = uvc_acquire_privileges(handle);
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >>  	if (fmt->type != stream->type)
> >>  		return -EINVAL;
> >>  
> >> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >>  		return ret;
> >>  
> >>  	mutex_lock(&stream->mutex);
> >> -
> >> -	if (uvc_queue_allocated(&stream->queue)) {
> >> +	if (vb2_is_busy(&stream->queue.queue)) {
> >>  		ret = -EBUSY;
> >>  		goto done;
> >>  	}
> >> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >>  	unsigned int i;
> >>  	int ret;
> >>  
> >> -	ret = uvc_acquire_privileges(handle);
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >>  	if (parm->type != stream->type)
> >>  		return -EINVAL;
> >>  
> >> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >>  	return 0;
> >>  }
> >>  
> >> -/* ------------------------------------------------------------------------
> >> - * Privilege management
> >> - */
> >> -
> >> -/*
> >> - * Privilege management is the multiple-open implementation basis. The current
> >> - * implementation is completely transparent for the end-user and doesn't
> >> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> >> - * Those ioctls enable finer control on the device (by making possible for a
> >> - * user to request exclusive access to a device), but are not mature yet.
> >> - * Switching to the V4L2 priority mechanism might be considered in the future
> >> - * if this situation changes.
> >> - *
> >> - * Each open instance of a UVC device can either be in a privileged or
> >> - * unprivileged state. Only a single instance can be in a privileged state at
> >> - * a given time. Trying to perform an operation that requires privileges will
> >> - * automatically acquire the required privileges if possible, or return -EBUSY
> >> - * otherwise. Privileges are dismissed when closing the instance or when
> >> - * freeing the video buffers using VIDIOC_REQBUFS.
> >> - *
> >> - * Operations that require privileges are:
> >> - *
> >> - * - VIDIOC_S_INPUT
> >> - * - VIDIOC_S_PARM
> >> - * - VIDIOC_S_FMT
> >> - * - VIDIOC_CREATE_BUFS
> >> - * - VIDIOC_REQBUFS
> >> - */
> >> -static int uvc_acquire_privileges(struct uvc_fh *handle)
> >> -{
> >> -	/* Always succeed if the handle is already privileged. */
> >> -	if (handle->state == UVC_HANDLE_ACTIVE)
> >> -		return 0;
> >> -
> >> -	/* Check if the device already has a privileged handle. */
> >> -	if (atomic_inc_return(&handle->stream->active) != 1) {
> >> -		atomic_dec(&handle->stream->active);
> >> -		return -EBUSY;
> >> -	}
> >> -
> >> -	handle->state = UVC_HANDLE_ACTIVE;
> >> -	return 0;
> >> -}
> >> -
> >> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> >> -{
> >> -	if (handle->state == UVC_HANDLE_ACTIVE)
> >> -		atomic_dec(&handle->stream->active);
> >> -
> >> -	handle->state = UVC_HANDLE_PASSIVE;
> >> -}
> >> -
> >> -static int uvc_has_privileges(struct uvc_fh *handle)
> >> -{
> >> -	return handle->state == UVC_HANDLE_ACTIVE;
> >> -}
> >> -
> >>  /* ------------------------------------------------------------------------
> >>   * V4L2 file operations
> >>   */
> >> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> >>  	v4l2_fh_add(&handle->vfh);
> >>  	handle->chain = stream->chain;
> >>  	handle->stream = stream;
> >> -	handle->state = UVC_HANDLE_PASSIVE;
> >>  	file->private_data = handle;
> >>  
> >>  	return 0;
> >> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> >>  
> >>  	uvc_ctrl_cleanup_fh(handle);
> >>  
> >> -	/* Only free resources if this is a privileged handle. */
> >> -	if (uvc_has_privileges(handle))
> >> -		uvc_queue_release(&stream->queue);
> >> -
> >>  	if (handle->is_streaming)
> >>  		uvc_pm_put(stream->dev);
> >>  
> >>  	/* Release the file handle. */
> >> -	uvc_dismiss_privileges(handle);
> >> -	v4l2_fh_del(&handle->vfh);
> >> -	v4l2_fh_exit(&handle->vfh);
> >> -	kfree(handle);
> >> +	vb2_fop_release(file);
> >>  	file->private_data = NULL;
> > 
> > You can drop setting private_data to NULL, it's done by
> > v4l2_fh_release() called by vb2_fop_release().
> > 
> >>  
> >>  	return 0;
> >> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> >>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> >>  }
> >>  
> >> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> >> -			     struct v4l2_requestbuffers *rb)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -	int ret;
> >> -
> >> -	ret = uvc_acquire_privileges(handle);
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >> -	mutex_lock(&stream->mutex);
> >> -	ret = uvc_request_buffers(&stream->queue, rb);
> >> -	mutex_unlock(&stream->mutex);
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >> -	if (ret == 0)
> >> -		uvc_dismiss_privileges(handle);
> >> -
> >> -	return 0;
> >> -}
> >> -
> >> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> >> -			      struct v4l2_buffer *buf)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	return uvc_query_buffer(&stream->queue, buf);
> >> -}
> >> -
> >> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	return uvc_queue_buffer(&stream->queue,
> >> -				stream->vdev.v4l2_dev->mdev, buf);
> >> -}
> >> -
> >> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> >> -			    struct v4l2_exportbuffer *exp)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	return uvc_export_buffer(&stream->queue, exp);
> >> -}
> >> -
> >> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	return uvc_dequeue_buffer(&stream->queue, buf,
> >> -				  file->f_flags & O_NONBLOCK);
> >> -}
> >> -
> >> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> >> -				  struct v4l2_create_buffers *cb)
> >> -{
> >> -	struct uvc_fh *handle = fh;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -	int ret;
> >> -
> >> -	ret = uvc_acquire_privileges(handle);
> >> -	if (ret < 0)
> >> -		return ret;
> >> -
> >> -	return uvc_create_buffers(&stream->queue, cb);
> >> -}
> >> -
> >>  static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>  			      enum v4l2_buf_type type)
> >>  {
> >> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>  	struct uvc_streaming *stream = handle->stream;
> >>  	int ret;
> >>  
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	guard(mutex)(&stream->mutex);
> >> -
> >>  	if (handle->is_streaming)
> >>  		return 0;
> >>  
> >> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>  	if (ret)
> >>  		return ret;
> >>  
> >> -	ret = uvc_queue_streamon(&stream->queue, type);
> >> +	ret = vb2_ioctl_streamon(file, fh, type);
> >>  	if (ret) {
> >>  		uvc_pm_put(stream->dev);
> >>  		return ret;
> >> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> >>  {
> >>  	struct uvc_fh *handle = fh;
> >>  	struct uvc_streaming *stream = handle->stream;
> >> +	int ret;
> >>  
> >> -	if (!uvc_has_privileges(handle))
> >> -		return -EBUSY;
> >> -
> >> -	guard(mutex)(&stream->mutex);
> >> +	ret = vb2_ioctl_streamoff(file, fh, type);
> >> +	if (ret)
> >> +		return ret;
> >>  
> >> -	uvc_queue_streamoff(&stream->queue, type);
> >>  	if (handle->is_streaming) {
> >>  		handle->is_streaming = false;
> >>  		uvc_pm_put(stream->dev);
> >> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> >>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> >>  {
> >>  	struct uvc_fh *handle = fh;
> >> +	struct uvc_streaming *stream = handle->stream;
> >>  	struct uvc_video_chain *chain = handle->chain;
> >>  	u8 *buf;
> >>  	int ret;
> >>  
> >> -	ret = uvc_acquire_privileges(handle);
> >> -	if (ret < 0)
> >> -		return ret;
> >> +	if (vb2_is_busy(&stream->queue.queue))
> >> +		return -EBUSY;
> >>  
> >>  	if (chain->selector == NULL ||
> >>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> >> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> >>  	return ret;
> >>  }
> >>  
> >> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> >> -		    size_t count, loff_t *ppos)
> >> -{
> >> -	struct uvc_fh *handle = file->private_data;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> >> -	return -EINVAL;
> >> -}
> >> -
> >> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> >> -{
> >> -	struct uvc_fh *handle = file->private_data;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >> -
> >> -	return uvc_queue_mmap(&stream->queue, vma);
> >> -}
> >> -
> >> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> >> -{
> >> -	struct uvc_fh *handle = file->private_data;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >> -
> >> -	return uvc_queue_poll(&stream->queue, file, wait);
> >> -}
> >> -
> >> -#ifndef CONFIG_MMU
> >> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> >> -		unsigned long addr, unsigned long len, unsigned long pgoff,
> >> -		unsigned long flags)
> >> -{
> >> -	struct uvc_fh *handle = file->private_data;
> >> -	struct uvc_streaming *stream = handle->stream;
> >> -
> >> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >> -
> >> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> >> -}
> >> -#endif
> >> -
> >>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> >>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> >> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> >>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> >>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> >> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
> >> -	.vidioc_querybuf = uvc_ioctl_querybuf,
> >> -	.vidioc_qbuf = uvc_ioctl_qbuf,
> >> -	.vidioc_expbuf = uvc_ioctl_expbuf,
> >> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
> >> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
> >> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> >> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> >> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> >> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> >> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> >> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> >> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> >>  	.vidioc_streamon = uvc_ioctl_streamon,
> >>  	.vidioc_streamoff = uvc_ioctl_streamoff,
> >>  	.vidioc_enum_input = uvc_ioctl_enum_input,
> >> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> >>  #ifdef CONFIG_COMPAT
> >>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
> >>  #endif
> >> -	.read		= uvc_v4l2_read,
> >> -	.mmap		= uvc_v4l2_mmap,
> >> -	.poll		= uvc_v4l2_poll,
> >> +	.mmap		= vb2_fop_mmap,
> >> +	.poll		= vb2_fop_poll,
> >>  #ifndef CONFIG_MMU
> >> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
> >> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
> >>  #endif
> >>  };
> >>  
> >> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> >> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> >> --- a/drivers/media/usb/uvc/uvcvideo.h
> >> +++ b/drivers/media/usb/uvc/uvcvideo.h
> >> @@ -326,7 +326,10 @@ struct uvc_buffer {
> >>  
> >>  struct uvc_video_queue {
> >>  	struct vb2_queue queue;
> >> -	struct mutex mutex;			/* Protects queue */
> >> +	struct mutex mutex;			/*
> >> +						 * Serializes vb2_queue and
> >> +						 * fops
> >> +						 */
> >>  
> >>  	unsigned int flags;
> >>  	unsigned int buf_used;
> >> @@ -349,7 +352,6 @@ struct uvc_video_chain {
> >>  						 * uvc_fh.pending_async_ctrls
> >>  						 */
> >>  
> >> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
> >>  	u32 caps;				/* V4L2 chain-wide caps */
> >>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
> >>  };
> >> @@ -619,16 +621,10 @@ struct uvc_device {
> >>  	struct uvc_entity *gpio_unit;
> >>  };
> >>  
> >> -enum uvc_handle_state {
> >> -	UVC_HANDLE_PASSIVE	= 0,
> >> -	UVC_HANDLE_ACTIVE	= 1,
> >> -};
> >> -
> >>  struct uvc_fh {
> >>  	struct v4l2_fh vfh;
> >>  	struct uvc_video_chain *chain;
> >>  	struct uvc_streaming *stream;
> >> -	enum uvc_handle_state state;
> >>  	unsigned int pending_async_ctrls;
> >>  	bool is_streaming;
> >>  };
> >> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> >>  
> >>  /* Video buffers queue management. */
> >>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >> -void uvc_queue_release(struct uvc_video_queue *queue);
> >> -int uvc_request_buffers(struct uvc_video_queue *queue,
> >> -			struct v4l2_requestbuffers *rb);
> >> -int uvc_query_buffer(struct uvc_video_queue *queue,
> >> -		     struct v4l2_buffer *v4l2_buf);
> >> -int uvc_create_buffers(struct uvc_video_queue *queue,
> >> -		       struct v4l2_create_buffers *v4l2_cb);
> >> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> >> -		     struct media_device *mdev,
> >> -		     struct v4l2_buffer *v4l2_buf);
> >> -int uvc_export_buffer(struct uvc_video_queue *queue,
> >> -		      struct v4l2_exportbuffer *exp);
> >> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> >> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
> >> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> >>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> >>  					 struct uvc_buffer *buf);
> >>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> >>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> >> -int uvc_queue_mmap(struct uvc_video_queue *queue,
> >> -		   struct vm_area_struct *vma);
> >> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> >> -			poll_table *wait);
> >> -#ifndef CONFIG_MMU
> >> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> >> -					  unsigned long pgoff);
> >> -#endif
> >> -int uvc_queue_allocated(struct uvc_video_queue *queue);
> >>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> >>  {
> >>  	return vb2_is_streaming(&queue->queue);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Hans Verkuil]

On 6/3/25 09:46, Laurent Pinchart wrote:
> Hi Hans,
> 
> On Mon, Jun 02, 2025 at 09:58:08PM +0200, Hans Verkuil wrote:
>> On 02/06/2025 20:31, Laurent Pinchart wrote:
>>> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
>>>> From: Hans Verkuil <hans@jjverkuil.nl>
>>>>
>>>> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
>>>>
>>>> This patch switches uvc over to those helpers, which removes a lot of
>>>> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
>>>
>>> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
>>> patch does related to priority is replace the per-chain priority
>>> handling with a per-device (as in uvc_device) priority, as the default
>>> is to use the prio state from v4l2_device. I think this is actually
>>> incorrect, a UVC device can have multiple independent streaming
>>> interfaces, so the priority ioctls should no operate on a device-wide
>>> prio state. Am I missing something ?
>>
>> The prio handling is per video_device. So an application that opens
>> /dev/videoX can raise the priority on the file handle to prevent other
>> applications that open the same video device from making changes.
>>
>>>> and allows us
>>>> to drop the 'privileges' scheme, since that's now handled inside the vb2
>>>> helpers.
>>>
>>> That part is correct. The driver implements a privilege-management
>>> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
>>> handlers, as the ioctl handlers didn't exist back then.
>>>
>>> Please reword the commit message to make this clearer. If the prio
>>> change is also desired, it should be split in a separate patch.
>>>
>>>> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
>>>>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
>>>>
>>>> This patch introduces a change on behavior on the uvcdriver to be
>>>> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
>>>> S_FORMAT do no grant exclusive ownership of the device.
>>>
>>> There are other changes in behaviour worth noting, some small, some
>>> quite substantial. Let's start with the small one: .vidioc_querybuf()
>>> now succeeds when the queue is busy. It seems a check may be missing in
>>> v4l2-compliance for this.
>>
>> It is perfectly fine querying buffers even if the queue is busy, it doesn't
>> affect streaming.
> 
> I agree, and I'm fine with the change in behaviour (as long as it gets
> mentioned in the commit message). My point is that the uvcvideo driver
> didn't allow it, and that wasn't caught by v4l2-compliance, so we're
> probably missing a test there.

I'm not sure there is anything wrong with how uvc behaves w.r.t. priority
handling today. So perhaps there is no need for v4l2-compliance to do
anything other than what it already does.

If we just keep the uvc prio code as-is, and v4l2-compliance doesn't complain
about that, then I don't see any need to change it.

Regards,

	Hans

> 
>>> The bigger change is related to locking. See below.
>>>
>>>> Reviewed-by: Hans de Goede <hansg@kernel.org>
>>>> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
>>>> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
>>>> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
>>>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>>>> ---
>>>>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
>>>>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
>>>>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
>>>>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
>>>>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
>>>>  5 files changed, 30 insertions(+), 443 deletions(-)
>>>>
>>>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>>>> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
>>>> --- a/drivers/media/usb/uvc/uvc_driver.c
>>>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>>>> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
>>>>  	INIT_LIST_HEAD(&chain->entities);
>>>>  	mutex_init(&chain->ctrl_mutex);
>>>>  	chain->dev = dev;
>>>> -	v4l2_prio_init(&chain->prio);
>>>>  
>>>>  	return chain;
>>>>  }
>>>> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
>>>>  		if (!video_is_registered(&stream->vdev))
>>>>  			continue;
>>>>  
>>>> -		/*
>>>> -		 * For stream->vdev we follow the same logic as:
>>>> -		 * vb2_video_unregister_device().
>>>> -		 */
>>>> -
>>>> -		/* 1. Take a reference to vdev */
>>>> -		get_device(&stream->vdev.dev);
>>>> -
>>>> -		/* 2. Ensure that no new ioctls can be called. */
>>>> -		video_unregister_device(&stream->vdev);
>>>> -
>>>> -		/* 3. Wait for old ioctls to finish. */
>>>> -		mutex_lock(&stream->mutex);
>>>> -
>>>> -		/* 4. Stop streaming. */
>>>> -		uvc_queue_release(&stream->queue);
>>>> -
>>>> -		mutex_unlock(&stream->mutex);
>>>> -
>>>> -		put_device(&stream->vdev.dev);
>>>> -
>>>> -		/*
>>>> -		 * For stream->meta.vdev we can directly call:
>>>> -		 * vb2_video_unregister_device().
>>>> -		 */
>>>> +		vb2_video_unregister_device(&stream->vdev);
>>>>  		vb2_video_unregister_device(&stream->meta.vdev);
>>>>  
>>>>  		/*
>>>> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
>>>>  	vdev->fops = fops;
>>>>  	vdev->ioctl_ops = ioctl_ops;
>>>>  	vdev->release = uvc_release;
>>>> -	vdev->prio = &stream->chain->prio;
>>>> +	vdev->queue = &queue->queue;
>>>> +	vdev->lock = &queue->mutex;
>>>
>>> This will cause the ioctl handlers to use queue->mutex for all ioctls
>>> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
>>> coarse, that should be mentioned in the commit message.
>>>
>>>>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
>>>>  		vdev->vfl_dir = VFL_DIR_TX;
>>>>  	else
>>>> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
>>>>  		if (stream->intf == intf) {
>>>>  			ret = uvc_video_resume(stream, reset);
>>>>  			if (ret < 0)
>>>> -				uvc_queue_streamoff(&stream->queue,
>>>> -						    stream->queue.queue.type);
>>>> +				vb2_streamoff(&stream->queue.queue,
>>>> +					      stream->queue.queue.type);
>>>
>>> This doesn't take any lock anymore. Can that be a problem ?
>>>
>>>>  			return ret;
>>>>  		}
>>>>  	}
>>>> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
>>>> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
>>>> --- a/drivers/media/usb/uvc/uvc_metadata.c
>>>> +++ b/drivers/media/usb/uvc/uvc_metadata.c
>>>> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
>>>>  	 */
>>>>  	mutex_lock(&stream->mutex);
>>>
>>> Is this lock still needed ? More broadly speaking, what's the remaining
>>> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
>>> drop queue->mutex, and use stream->mutex everywhere instead ?
>>>
>>>>  
>>>> -	if (uvc_queue_allocated(&stream->queue))
>>>> +	if (vb2_is_busy(&stream->meta.queue.queue))
>>>>  		ret = -EBUSY;
>>>>  	else
>>>>  		stream->meta.format = fmt->dataformat;
>>>> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
>>>>  
>>>>  	stream->meta.format = V4L2_META_FMT_UVC;
>>>>  
>>>> -	/*
>>>> -	 * The video interface queue uses manual locking and thus does not set
>>>> -	 * the queue pointer. Set it manually here.
>>>> -	 */
>>>> -	vdev->queue = &queue->queue;
>>>> -
>>>>  	return uvc_register_video_device(dev, stream, vdev, queue,
>>>>  					 V4L2_BUF_TYPE_META_CAPTURE,
>>>>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
>>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
>>>> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
>>>> --- a/drivers/media/usb/uvc/uvc_queue.c
>>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
>>>> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>>  	return 0;
>>>>  }
>>>>  
>>>> -void uvc_queue_release(struct uvc_video_queue *queue)
>>>> -{
>>>> -	mutex_lock(&queue->mutex);
>>>> -	vb2_queue_release(&queue->queue);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -}
>>>> -
>>>> -/* -----------------------------------------------------------------------------
>>>> - * V4L2 queue operations
>>>> - */
>>>> -
>>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>>> -			struct v4l2_requestbuffers *rb)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_reqbufs(&queue->queue, rb);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret ? ret : rb->count;
>>>> -}
>>>> -
>>>> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_querybuf(&queue->queue, buf);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>>> -		       struct v4l2_create_buffers *cb)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_create_bufs(&queue->queue, cb);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>>> -		     struct media_device *mdev, struct v4l2_buffer *buf)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>>> -		      struct v4l2_exportbuffer *exp)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_expbuf(&queue->queue, exp);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
>>>> -		       int nonblocking)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_streamon(&queue->queue, type);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>> -{
>>>> -	int ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_streamoff(&queue->queue, type);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
>>>> -{
>>>> -	return vb2_mmap(&queue->queue, vma);
>>>> -}
>>>> -
>>>> -#ifndef CONFIG_MMU
>>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>>> -		unsigned long pgoff)
>>>> -{
>>>> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
>>>> -}
>>>> -#endif
>>>> -
>>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>>> -			    poll_table *wait)
>>>> -{
>>>> -	__poll_t ret;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	ret = vb2_poll(&queue->queue, file, wait);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return ret;
>>>> -}
>>>> -
>>>>  /* -----------------------------------------------------------------------------
>>>>   *
>>>>   */
>>>>  
>>>> -/*
>>>> - * Check if buffers have been allocated.
>>>> - */
>>>> -int uvc_queue_allocated(struct uvc_video_queue *queue)
>>>> -{
>>>> -	int allocated;
>>>> -
>>>> -	mutex_lock(&queue->mutex);
>>>> -	allocated = vb2_is_busy(&queue->queue);
>>>> -	mutex_unlock(&queue->mutex);
>>>> -
>>>> -	return allocated;
>>>> -}
>>>> -
>>>>  /*
>>>>   * Cancel the video buffers queue.
>>>>   *
>>>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
>>>> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
>>>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>>>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>>>> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
>>>>  	usb_autopm_put_interface(dev->intf);
>>>>  }
>>>>  
>>>> -static int uvc_acquire_privileges(struct uvc_fh *handle);
>>>> -
>>>>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
>>>>  				      struct uvc_control_mapping *map,
>>>>  				      const struct uvc_xu_control_mapping *xmap)
>>>> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>>  	const struct uvc_frame *frame;
>>>>  	int ret;
>>>>  
>>>> -	ret = uvc_acquire_privileges(handle);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> -
>>>>  	if (fmt->type != stream->type)
>>>>  		return -EINVAL;
>>>>  
>>>> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>>  		return ret;
>>>>  
>>>>  	mutex_lock(&stream->mutex);
>>>> -
>>>> -	if (uvc_queue_allocated(&stream->queue)) {
>>>> +	if (vb2_is_busy(&stream->queue.queue)) {
>>>>  		ret = -EBUSY;
>>>>  		goto done;
>>>>  	}
>>>> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>>  	unsigned int i;
>>>>  	int ret;
>>>>  
>>>> -	ret = uvc_acquire_privileges(handle);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> -
>>>>  	if (parm->type != stream->type)
>>>>  		return -EINVAL;
>>>>  
>>>> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>>  	return 0;
>>>>  }
>>>>  
>>>> -/* ------------------------------------------------------------------------
>>>> - * Privilege management
>>>> - */
>>>> -
>>>> -/*
>>>> - * Privilege management is the multiple-open implementation basis. The current
>>>> - * implementation is completely transparent for the end-user and doesn't
>>>> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
>>>> - * Those ioctls enable finer control on the device (by making possible for a
>>>> - * user to request exclusive access to a device), but are not mature yet.
>>>> - * Switching to the V4L2 priority mechanism might be considered in the future
>>>> - * if this situation changes.
>>>> - *
>>>> - * Each open instance of a UVC device can either be in a privileged or
>>>> - * unprivileged state. Only a single instance can be in a privileged state at
>>>> - * a given time. Trying to perform an operation that requires privileges will
>>>> - * automatically acquire the required privileges if possible, or return -EBUSY
>>>> - * otherwise. Privileges are dismissed when closing the instance or when
>>>> - * freeing the video buffers using VIDIOC_REQBUFS.
>>>> - *
>>>> - * Operations that require privileges are:
>>>> - *
>>>> - * - VIDIOC_S_INPUT
>>>> - * - VIDIOC_S_PARM
>>>> - * - VIDIOC_S_FMT
>>>> - * - VIDIOC_CREATE_BUFS
>>>> - * - VIDIOC_REQBUFS
>>>> - */
>>>> -static int uvc_acquire_privileges(struct uvc_fh *handle)
>>>> -{
>>>> -	/* Always succeed if the handle is already privileged. */
>>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>>> -		return 0;
>>>> -
>>>> -	/* Check if the device already has a privileged handle. */
>>>> -	if (atomic_inc_return(&handle->stream->active) != 1) {
>>>> -		atomic_dec(&handle->stream->active);
>>>> -		return -EBUSY;
>>>> -	}
>>>> -
>>>> -	handle->state = UVC_HANDLE_ACTIVE;
>>>> -	return 0;
>>>> -}
>>>> -
>>>> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
>>>> -{
>>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>>> -		atomic_dec(&handle->stream->active);
>>>> -
>>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>>> -}
>>>> -
>>>> -static int uvc_has_privileges(struct uvc_fh *handle)
>>>> -{
>>>> -	return handle->state == UVC_HANDLE_ACTIVE;
>>>> -}
>>>> -
>>>>  /* ------------------------------------------------------------------------
>>>>   * V4L2 file operations
>>>>   */
>>>> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
>>>>  	v4l2_fh_add(&handle->vfh);
>>>>  	handle->chain = stream->chain;
>>>>  	handle->stream = stream;
>>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>>>  	file->private_data = handle;
>>>>  
>>>>  	return 0;
>>>> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
>>>>  
>>>>  	uvc_ctrl_cleanup_fh(handle);
>>>>  
>>>> -	/* Only free resources if this is a privileged handle. */
>>>> -	if (uvc_has_privileges(handle))
>>>> -		uvc_queue_release(&stream->queue);
>>>> -
>>>>  	if (handle->is_streaming)
>>>>  		uvc_pm_put(stream->dev);
>>>>  
>>>>  	/* Release the file handle. */
>>>> -	uvc_dismiss_privileges(handle);
>>>> -	v4l2_fh_del(&handle->vfh);
>>>> -	v4l2_fh_exit(&handle->vfh);
>>>> -	kfree(handle);
>>>> +	vb2_fop_release(file);
>>>>  	file->private_data = NULL;
>>>
>>> You can drop setting private_data to NULL, it's done by
>>> v4l2_fh_release() called by vb2_fop_release().
>>>
>>>>  
>>>>  	return 0;
>>>> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>>>>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>>>>  }
>>>>  
>>>> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
>>>> -			     struct v4l2_requestbuffers *rb)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -	int ret;
>>>> -
>>>> -	ret = uvc_acquire_privileges(handle);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> -
>>>> -	mutex_lock(&stream->mutex);
>>>> -	ret = uvc_request_buffers(&stream->queue, rb);
>>>> -	mutex_unlock(&stream->mutex);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> -
>>>> -	if (ret == 0)
>>>> -		uvc_dismiss_privileges(handle);
>>>> -
>>>> -	return 0;
>>>> -}
>>>> -
>>>> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
>>>> -			      struct v4l2_buffer *buf)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	return uvc_query_buffer(&stream->queue, buf);
>>>> -}
>>>> -
>>>> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	return uvc_queue_buffer(&stream->queue,
>>>> -				stream->vdev.v4l2_dev->mdev, buf);
>>>> -}
>>>> -
>>>> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
>>>> -			    struct v4l2_exportbuffer *exp)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	return uvc_export_buffer(&stream->queue, exp);
>>>> -}
>>>> -
>>>> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	return uvc_dequeue_buffer(&stream->queue, buf,
>>>> -				  file->f_flags & O_NONBLOCK);
>>>> -}
>>>> -
>>>> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
>>>> -				  struct v4l2_create_buffers *cb)
>>>> -{
>>>> -	struct uvc_fh *handle = fh;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -	int ret;
>>>> -
>>>> -	ret = uvc_acquire_privileges(handle);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> -
>>>> -	return uvc_create_buffers(&stream->queue, cb);
>>>> -}
>>>> -
>>>>  static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>  			      enum v4l2_buf_type type)
>>>>  {
>>>> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>  	struct uvc_streaming *stream = handle->stream;
>>>>  	int ret;
>>>>  
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	guard(mutex)(&stream->mutex);
>>>> -
>>>>  	if (handle->is_streaming)
>>>>  		return 0;
>>>>  
>>>> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>  	if (ret)
>>>>  		return ret;
>>>>  
>>>> -	ret = uvc_queue_streamon(&stream->queue, type);
>>>> +	ret = vb2_ioctl_streamon(file, fh, type);
>>>>  	if (ret) {
>>>>  		uvc_pm_put(stream->dev);
>>>>  		return ret;
>>>> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
>>>>  {
>>>>  	struct uvc_fh *handle = fh;
>>>>  	struct uvc_streaming *stream = handle->stream;
>>>> +	int ret;
>>>>  
>>>> -	if (!uvc_has_privileges(handle))
>>>> -		return -EBUSY;
>>>> -
>>>> -	guard(mutex)(&stream->mutex);
>>>> +	ret = vb2_ioctl_streamoff(file, fh, type);
>>>> +	if (ret)
>>>> +		return ret;
>>>>  
>>>> -	uvc_queue_streamoff(&stream->queue, type);
>>>>  	if (handle->is_streaming) {
>>>>  		handle->is_streaming = false;
>>>>  		uvc_pm_put(stream->dev);
>>>> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
>>>>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
>>>>  {
>>>>  	struct uvc_fh *handle = fh;
>>>> +	struct uvc_streaming *stream = handle->stream;
>>>>  	struct uvc_video_chain *chain = handle->chain;
>>>>  	u8 *buf;
>>>>  	int ret;
>>>>  
>>>> -	ret = uvc_acquire_privileges(handle);
>>>> -	if (ret < 0)
>>>> -		return ret;
>>>> +	if (vb2_is_busy(&stream->queue.queue))
>>>> +		return -EBUSY;
>>>>  
>>>>  	if (chain->selector == NULL ||
>>>>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
>>>> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>>>>  	return ret;
>>>>  }
>>>>  
>>>> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
>>>> -		    size_t count, loff_t *ppos)
>>>> -{
>>>> -	struct uvc_fh *handle = file->private_data;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
>>>> -	return -EINVAL;
>>>> -}
>>>> -
>>>> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
>>>> -{
>>>> -	struct uvc_fh *handle = file->private_data;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>> -
>>>> -	return uvc_queue_mmap(&stream->queue, vma);
>>>> -}
>>>> -
>>>> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
>>>> -{
>>>> -	struct uvc_fh *handle = file->private_data;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>> -
>>>> -	return uvc_queue_poll(&stream->queue, file, wait);
>>>> -}
>>>> -
>>>> -#ifndef CONFIG_MMU
>>>> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
>>>> -		unsigned long addr, unsigned long len, unsigned long pgoff,
>>>> -		unsigned long flags)
>>>> -{
>>>> -	struct uvc_fh *handle = file->private_data;
>>>> -	struct uvc_streaming *stream = handle->stream;
>>>> -
>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>> -
>>>> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
>>>> -}
>>>> -#endif
>>>> -
>>>>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>>>>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>>>> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
>>>>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
>>>>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
>>>> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
>>>> -	.vidioc_querybuf = uvc_ioctl_querybuf,
>>>> -	.vidioc_qbuf = uvc_ioctl_qbuf,
>>>> -	.vidioc_expbuf = uvc_ioctl_expbuf,
>>>> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
>>>> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
>>>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>>>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>>>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>>>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>>>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
>>>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>>>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>>>>  	.vidioc_streamon = uvc_ioctl_streamon,
>>>>  	.vidioc_streamoff = uvc_ioctl_streamoff,
>>>>  	.vidioc_enum_input = uvc_ioctl_enum_input,
>>>> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
>>>>  #ifdef CONFIG_COMPAT
>>>>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
>>>>  #endif
>>>> -	.read		= uvc_v4l2_read,
>>>> -	.mmap		= uvc_v4l2_mmap,
>>>> -	.poll		= uvc_v4l2_poll,
>>>> +	.mmap		= vb2_fop_mmap,
>>>> +	.poll		= vb2_fop_poll,
>>>>  #ifndef CONFIG_MMU
>>>> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
>>>> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
>>>>  #endif
>>>>  };
>>>>  
>>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
>>>> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
>>>> --- a/drivers/media/usb/uvc/uvcvideo.h
>>>> +++ b/drivers/media/usb/uvc/uvcvideo.h
>>>> @@ -326,7 +326,10 @@ struct uvc_buffer {
>>>>  
>>>>  struct uvc_video_queue {
>>>>  	struct vb2_queue queue;
>>>> -	struct mutex mutex;			/* Protects queue */
>>>> +	struct mutex mutex;			/*
>>>> +						 * Serializes vb2_queue and
>>>> +						 * fops
>>>> +						 */
>>>>  
>>>>  	unsigned int flags;
>>>>  	unsigned int buf_used;
>>>> @@ -349,7 +352,6 @@ struct uvc_video_chain {
>>>>  						 * uvc_fh.pending_async_ctrls
>>>>  						 */
>>>>  
>>>> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
>>>>  	u32 caps;				/* V4L2 chain-wide caps */
>>>>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
>>>>  };
>>>> @@ -619,16 +621,10 @@ struct uvc_device {
>>>>  	struct uvc_entity *gpio_unit;
>>>>  };
>>>>  
>>>> -enum uvc_handle_state {
>>>> -	UVC_HANDLE_PASSIVE	= 0,
>>>> -	UVC_HANDLE_ACTIVE	= 1,
>>>> -};
>>>> -
>>>>  struct uvc_fh {
>>>>  	struct v4l2_fh vfh;
>>>>  	struct uvc_video_chain *chain;
>>>>  	struct uvc_streaming *stream;
>>>> -	enum uvc_handle_state state;
>>>>  	unsigned int pending_async_ctrls;
>>>>  	bool is_streaming;
>>>>  };
>>>> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>>>>  
>>>>  /* Video buffers queue management. */
>>>>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>> -void uvc_queue_release(struct uvc_video_queue *queue);
>>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>>> -			struct v4l2_requestbuffers *rb);
>>>> -int uvc_query_buffer(struct uvc_video_queue *queue,
>>>> -		     struct v4l2_buffer *v4l2_buf);
>>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>>> -		       struct v4l2_create_buffers *v4l2_cb);
>>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>>> -		     struct media_device *mdev,
>>>> -		     struct v4l2_buffer *v4l2_buf);
>>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>>> -		      struct v4l2_exportbuffer *exp);
>>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
>>>> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
>>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>>>>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>>>>  					 struct uvc_buffer *buf);
>>>>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
>>>>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
>>>> -int uvc_queue_mmap(struct uvc_video_queue *queue,
>>>> -		   struct vm_area_struct *vma);
>>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>>> -			poll_table *wait);
>>>> -#ifndef CONFIG_MMU
>>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>>> -					  unsigned long pgoff);
>>>> -#endif
>>>> -int uvc_queue_allocated(struct uvc_video_queue *queue);
>>>>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>>>>  {
>>>>  	return vb2_is_streaming(&queue->queue);
> 

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Laurent Pinchart]

On Tue, Jun 03, 2025 at 10:22:47AM +0200, Hans Verkuil wrote:
> On 6/3/25 09:46, Laurent Pinchart wrote:
> > On Mon, Jun 02, 2025 at 09:58:08PM +0200, Hans Verkuil wrote:
> >> On 02/06/2025 20:31, Laurent Pinchart wrote:
> >>> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> >>>> From: Hans Verkuil <hans@jjverkuil.nl>
> >>>>
> >>>> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> >>>>
> >>>> This patch switches uvc over to those helpers, which removes a lot of
> >>>> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> >>>
> >>> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> >>> patch does related to priority is replace the per-chain priority
> >>> handling with a per-device (as in uvc_device) priority, as the default
> >>> is to use the prio state from v4l2_device. I think this is actually
> >>> incorrect, a UVC device can have multiple independent streaming
> >>> interfaces, so the priority ioctls should no operate on a device-wide
> >>> prio state. Am I missing something ?
> >>
> >> The prio handling is per video_device. So an application that opens
> >> /dev/videoX can raise the priority on the file handle to prevent other
> >> applications that open the same video device from making changes.
> >>
> >>>> and allows us
> >>>> to drop the 'privileges' scheme, since that's now handled inside the vb2
> >>>> helpers.
> >>>
> >>> That part is correct. The driver implements a privilege-management
> >>> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> >>> handlers, as the ioctl handlers didn't exist back then.
> >>>
> >>> Please reword the commit message to make this clearer. If the prio
> >>> change is also desired, it should be split in a separate patch.
> >>>
> >>>> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> >>>>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> >>>>
> >>>> This patch introduces a change on behavior on the uvcdriver to be
> >>>> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> >>>> S_FORMAT do no grant exclusive ownership of the device.
> >>>
> >>> There are other changes in behaviour worth noting, some small, some
> >>> quite substantial. Let's start with the small one: .vidioc_querybuf()
> >>> now succeeds when the queue is busy. It seems a check may be missing in
> >>> v4l2-compliance for this.
> >>
> >> It is perfectly fine querying buffers even if the queue is busy, it doesn't
> >> affect streaming.
> > 
> > I agree, and I'm fine with the change in behaviour (as long as it gets
> > mentioned in the commit message). My point is that the uvcvideo driver
> > didn't allow it, and that wasn't caught by v4l2-compliance, so we're
> > probably missing a test there.
> 
> I'm not sure there is anything wrong with how uvc behaves w.r.t. priority
> handling today. So perhaps there is no need for v4l2-compliance to do
> anything other than what it already does.

It's not about prio. If you call VIDIOC_QUERYBUF on uvcvideo device that
is busy due to another process, the call will fail with -EBUSY. The V4L2
specification doesn't allow that behaviour as far as I understand, and
other V4L2 drivers happily handle QUERYBUF on a busy queue. This patch
fixes it, and I think this deserves a v4l2-compliance check.

> If we just keep the uvc prio code as-is, and v4l2-compliance doesn't complain
> about that, then I don't see any need to change it.
> 
> >>> The bigger change is related to locking. See below.
> >>>
> >>>> Reviewed-by: Hans de Goede <hansg@kernel.org>
> >>>> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> >>>> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> >>>> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> >>>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> >>>> ---
> >>>>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> >>>>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> >>>>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> >>>>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> >>>>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> >>>>  5 files changed, 30 insertions(+), 443 deletions(-)
> >>>>
> >>>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> >>>> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> >>>> --- a/drivers/media/usb/uvc/uvc_driver.c
> >>>> +++ b/drivers/media/usb/uvc/uvc_driver.c
> >>>> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> >>>>  	INIT_LIST_HEAD(&chain->entities);
> >>>>  	mutex_init(&chain->ctrl_mutex);
> >>>>  	chain->dev = dev;
> >>>> -	v4l2_prio_init(&chain->prio);
> >>>>  
> >>>>  	return chain;
> >>>>  }
> >>>> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> >>>>  		if (!video_is_registered(&stream->vdev))
> >>>>  			continue;
> >>>>  
> >>>> -		/*
> >>>> -		 * For stream->vdev we follow the same logic as:
> >>>> -		 * vb2_video_unregister_device().
> >>>> -		 */
> >>>> -
> >>>> -		/* 1. Take a reference to vdev */
> >>>> -		get_device(&stream->vdev.dev);
> >>>> -
> >>>> -		/* 2. Ensure that no new ioctls can be called. */
> >>>> -		video_unregister_device(&stream->vdev);
> >>>> -
> >>>> -		/* 3. Wait for old ioctls to finish. */
> >>>> -		mutex_lock(&stream->mutex);
> >>>> -
> >>>> -		/* 4. Stop streaming. */
> >>>> -		uvc_queue_release(&stream->queue);
> >>>> -
> >>>> -		mutex_unlock(&stream->mutex);
> >>>> -
> >>>> -		put_device(&stream->vdev.dev);
> >>>> -
> >>>> -		/*
> >>>> -		 * For stream->meta.vdev we can directly call:
> >>>> -		 * vb2_video_unregister_device().
> >>>> -		 */
> >>>> +		vb2_video_unregister_device(&stream->vdev);
> >>>>  		vb2_video_unregister_device(&stream->meta.vdev);
> >>>>  
> >>>>  		/*
> >>>> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> >>>>  	vdev->fops = fops;
> >>>>  	vdev->ioctl_ops = ioctl_ops;
> >>>>  	vdev->release = uvc_release;
> >>>> -	vdev->prio = &stream->chain->prio;
> >>>> +	vdev->queue = &queue->queue;
> >>>> +	vdev->lock = &queue->mutex;
> >>>
> >>> This will cause the ioctl handlers to use queue->mutex for all ioctls
> >>> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> >>> coarse, that should be mentioned in the commit message.
> >>>
> >>>>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> >>>>  		vdev->vfl_dir = VFL_DIR_TX;
> >>>>  	else
> >>>> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> >>>>  		if (stream->intf == intf) {
> >>>>  			ret = uvc_video_resume(stream, reset);
> >>>>  			if (ret < 0)
> >>>> -				uvc_queue_streamoff(&stream->queue,
> >>>> -						    stream->queue.queue.type);
> >>>> +				vb2_streamoff(&stream->queue.queue,
> >>>> +					      stream->queue.queue.type);
> >>>
> >>> This doesn't take any lock anymore. Can that be a problem ?
> >>>
> >>>>  			return ret;
> >>>>  		}
> >>>>  	}
> >>>> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> >>>> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> >>>> --- a/drivers/media/usb/uvc/uvc_metadata.c
> >>>> +++ b/drivers/media/usb/uvc/uvc_metadata.c
> >>>> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> >>>>  	 */
> >>>>  	mutex_lock(&stream->mutex);
> >>>
> >>> Is this lock still needed ? More broadly speaking, what's the remaining
> >>> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> >>> drop queue->mutex, and use stream->mutex everywhere instead ?
> >>>
> >>>>  
> >>>> -	if (uvc_queue_allocated(&stream->queue))
> >>>> +	if (vb2_is_busy(&stream->meta.queue.queue))
> >>>>  		ret = -EBUSY;
> >>>>  	else
> >>>>  		stream->meta.format = fmt->dataformat;
> >>>> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> >>>>  
> >>>>  	stream->meta.format = V4L2_META_FMT_UVC;
> >>>>  
> >>>> -	/*
> >>>> -	 * The video interface queue uses manual locking and thus does not set
> >>>> -	 * the queue pointer. Set it manually here.
> >>>> -	 */
> >>>> -	vdev->queue = &queue->queue;
> >>>> -
> >>>>  	return uvc_register_video_device(dev, stream, vdev, queue,
> >>>>  					 V4L2_BUF_TYPE_META_CAPTURE,
> >>>>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
> >>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> >>>> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> >>>> --- a/drivers/media/usb/uvc/uvc_queue.c
> >>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
> >>>> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >>>>  	return 0;
> >>>>  }
> >>>>  
> >>>> -void uvc_queue_release(struct uvc_video_queue *queue)
> >>>> -{
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	vb2_queue_release(&queue->queue);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -}
> >>>> -
> >>>> -/* -----------------------------------------------------------------------------
> >>>> - * V4L2 queue operations
> >>>> - */
> >>>> -
> >>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
> >>>> -			struct v4l2_requestbuffers *rb)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_reqbufs(&queue->queue, rb);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret ? ret : rb->count;
> >>>> -}
> >>>> -
> >>>> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_querybuf(&queue->queue, buf);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
> >>>> -		       struct v4l2_create_buffers *cb)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_create_bufs(&queue->queue, cb);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> >>>> -		     struct media_device *mdev, struct v4l2_buffer *buf)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
> >>>> -		      struct v4l2_exportbuffer *exp)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_expbuf(&queue->queue, exp);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> >>>> -		       int nonblocking)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_streamon(&queue->queue, type);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> >>>> -{
> >>>> -	int ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_streamoff(&queue->queue, type);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> >>>> -{
> >>>> -	return vb2_mmap(&queue->queue, vma);
> >>>> -}
> >>>> -
> >>>> -#ifndef CONFIG_MMU
> >>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> >>>> -		unsigned long pgoff)
> >>>> -{
> >>>> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> >>>> -}
> >>>> -#endif
> >>>> -
> >>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> >>>> -			    poll_table *wait)
> >>>> -{
> >>>> -	__poll_t ret;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	ret = vb2_poll(&queue->queue, file, wait);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return ret;
> >>>> -}
> >>>> -
> >>>>  /* -----------------------------------------------------------------------------
> >>>>   *
> >>>>   */
> >>>>  
> >>>> -/*
> >>>> - * Check if buffers have been allocated.
> >>>> - */
> >>>> -int uvc_queue_allocated(struct uvc_video_queue *queue)
> >>>> -{
> >>>> -	int allocated;
> >>>> -
> >>>> -	mutex_lock(&queue->mutex);
> >>>> -	allocated = vb2_is_busy(&queue->queue);
> >>>> -	mutex_unlock(&queue->mutex);
> >>>> -
> >>>> -	return allocated;
> >>>> -}
> >>>> -
> >>>>  /*
> >>>>   * Cancel the video buffers queue.
> >>>>   *
> >>>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> >>>> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> >>>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> >>>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> >>>> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> >>>>  	usb_autopm_put_interface(dev->intf);
> >>>>  }
> >>>>  
> >>>> -static int uvc_acquire_privileges(struct uvc_fh *handle);
> >>>> -
> >>>>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> >>>>  				      struct uvc_control_mapping *map,
> >>>>  				      const struct uvc_xu_control_mapping *xmap)
> >>>> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >>>>  	const struct uvc_frame *frame;
> >>>>  	int ret;
> >>>>  
> >>>> -	ret = uvc_acquire_privileges(handle);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> -
> >>>>  	if (fmt->type != stream->type)
> >>>>  		return -EINVAL;
> >>>>  
> >>>> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> >>>>  		return ret;
> >>>>  
> >>>>  	mutex_lock(&stream->mutex);
> >>>> -
> >>>> -	if (uvc_queue_allocated(&stream->queue)) {
> >>>> +	if (vb2_is_busy(&stream->queue.queue)) {
> >>>>  		ret = -EBUSY;
> >>>>  		goto done;
> >>>>  	}
> >>>> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >>>>  	unsigned int i;
> >>>>  	int ret;
> >>>>  
> >>>> -	ret = uvc_acquire_privileges(handle);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> -
> >>>>  	if (parm->type != stream->type)
> >>>>  		return -EINVAL;
> >>>>  
> >>>> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> >>>>  	return 0;
> >>>>  }
> >>>>  
> >>>> -/* ------------------------------------------------------------------------
> >>>> - * Privilege management
> >>>> - */
> >>>> -
> >>>> -/*
> >>>> - * Privilege management is the multiple-open implementation basis. The current
> >>>> - * implementation is completely transparent for the end-user and doesn't
> >>>> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> >>>> - * Those ioctls enable finer control on the device (by making possible for a
> >>>> - * user to request exclusive access to a device), but are not mature yet.
> >>>> - * Switching to the V4L2 priority mechanism might be considered in the future
> >>>> - * if this situation changes.
> >>>> - *
> >>>> - * Each open instance of a UVC device can either be in a privileged or
> >>>> - * unprivileged state. Only a single instance can be in a privileged state at
> >>>> - * a given time. Trying to perform an operation that requires privileges will
> >>>> - * automatically acquire the required privileges if possible, or return -EBUSY
> >>>> - * otherwise. Privileges are dismissed when closing the instance or when
> >>>> - * freeing the video buffers using VIDIOC_REQBUFS.
> >>>> - *
> >>>> - * Operations that require privileges are:
> >>>> - *
> >>>> - * - VIDIOC_S_INPUT
> >>>> - * - VIDIOC_S_PARM
> >>>> - * - VIDIOC_S_FMT
> >>>> - * - VIDIOC_CREATE_BUFS
> >>>> - * - VIDIOC_REQBUFS
> >>>> - */
> >>>> -static int uvc_acquire_privileges(struct uvc_fh *handle)
> >>>> -{
> >>>> -	/* Always succeed if the handle is already privileged. */
> >>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
> >>>> -		return 0;
> >>>> -
> >>>> -	/* Check if the device already has a privileged handle. */
> >>>> -	if (atomic_inc_return(&handle->stream->active) != 1) {
> >>>> -		atomic_dec(&handle->stream->active);
> >>>> -		return -EBUSY;
> >>>> -	}
> >>>> -
> >>>> -	handle->state = UVC_HANDLE_ACTIVE;
> >>>> -	return 0;
> >>>> -}
> >>>> -
> >>>> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> >>>> -{
> >>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
> >>>> -		atomic_dec(&handle->stream->active);
> >>>> -
> >>>> -	handle->state = UVC_HANDLE_PASSIVE;
> >>>> -}
> >>>> -
> >>>> -static int uvc_has_privileges(struct uvc_fh *handle)
> >>>> -{
> >>>> -	return handle->state == UVC_HANDLE_ACTIVE;
> >>>> -}
> >>>> -
> >>>>  /* ------------------------------------------------------------------------
> >>>>   * V4L2 file operations
> >>>>   */
> >>>> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> >>>>  	v4l2_fh_add(&handle->vfh);
> >>>>  	handle->chain = stream->chain;
> >>>>  	handle->stream = stream;
> >>>> -	handle->state = UVC_HANDLE_PASSIVE;
> >>>>  	file->private_data = handle;
> >>>>  
> >>>>  	return 0;
> >>>> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> >>>>  
> >>>>  	uvc_ctrl_cleanup_fh(handle);
> >>>>  
> >>>> -	/* Only free resources if this is a privileged handle. */
> >>>> -	if (uvc_has_privileges(handle))
> >>>> -		uvc_queue_release(&stream->queue);
> >>>> -
> >>>>  	if (handle->is_streaming)
> >>>>  		uvc_pm_put(stream->dev);
> >>>>  
> >>>>  	/* Release the file handle. */
> >>>> -	uvc_dismiss_privileges(handle);
> >>>> -	v4l2_fh_del(&handle->vfh);
> >>>> -	v4l2_fh_exit(&handle->vfh);
> >>>> -	kfree(handle);
> >>>> +	vb2_fop_release(file);
> >>>>  	file->private_data = NULL;
> >>>
> >>> You can drop setting private_data to NULL, it's done by
> >>> v4l2_fh_release() called by vb2_fop_release().
> >>>
> >>>>  
> >>>>  	return 0;
> >>>> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> >>>>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> >>>>  }
> >>>>  
> >>>> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> >>>> -			     struct v4l2_requestbuffers *rb)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -	int ret;
> >>>> -
> >>>> -	ret = uvc_acquire_privileges(handle);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> -
> >>>> -	mutex_lock(&stream->mutex);
> >>>> -	ret = uvc_request_buffers(&stream->queue, rb);
> >>>> -	mutex_unlock(&stream->mutex);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> -
> >>>> -	if (ret == 0)
> >>>> -		uvc_dismiss_privileges(handle);
> >>>> -
> >>>> -	return 0;
> >>>> -}
> >>>> -
> >>>> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> >>>> -			      struct v4l2_buffer *buf)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	return uvc_query_buffer(&stream->queue, buf);
> >>>> -}
> >>>> -
> >>>> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	return uvc_queue_buffer(&stream->queue,
> >>>> -				stream->vdev.v4l2_dev->mdev, buf);
> >>>> -}
> >>>> -
> >>>> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> >>>> -			    struct v4l2_exportbuffer *exp)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	return uvc_export_buffer(&stream->queue, exp);
> >>>> -}
> >>>> -
> >>>> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	return uvc_dequeue_buffer(&stream->queue, buf,
> >>>> -				  file->f_flags & O_NONBLOCK);
> >>>> -}
> >>>> -
> >>>> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> >>>> -				  struct v4l2_create_buffers *cb)
> >>>> -{
> >>>> -	struct uvc_fh *handle = fh;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -	int ret;
> >>>> -
> >>>> -	ret = uvc_acquire_privileges(handle);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> -
> >>>> -	return uvc_create_buffers(&stream->queue, cb);
> >>>> -}
> >>>> -
> >>>>  static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>>>  			      enum v4l2_buf_type type)
> >>>>  {
> >>>> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>>>  	struct uvc_streaming *stream = handle->stream;
> >>>>  	int ret;
> >>>>  
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	guard(mutex)(&stream->mutex);
> >>>> -
> >>>>  	if (handle->is_streaming)
> >>>>  		return 0;
> >>>>  
> >>>> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> >>>>  	if (ret)
> >>>>  		return ret;
> >>>>  
> >>>> -	ret = uvc_queue_streamon(&stream->queue, type);
> >>>> +	ret = vb2_ioctl_streamon(file, fh, type);
> >>>>  	if (ret) {
> >>>>  		uvc_pm_put(stream->dev);
> >>>>  		return ret;
> >>>> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> >>>>  {
> >>>>  	struct uvc_fh *handle = fh;
> >>>>  	struct uvc_streaming *stream = handle->stream;
> >>>> +	int ret;
> >>>>  
> >>>> -	if (!uvc_has_privileges(handle))
> >>>> -		return -EBUSY;
> >>>> -
> >>>> -	guard(mutex)(&stream->mutex);
> >>>> +	ret = vb2_ioctl_streamoff(file, fh, type);
> >>>> +	if (ret)
> >>>> +		return ret;
> >>>>  
> >>>> -	uvc_queue_streamoff(&stream->queue, type);
> >>>>  	if (handle->is_streaming) {
> >>>>  		handle->is_streaming = false;
> >>>>  		uvc_pm_put(stream->dev);
> >>>> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> >>>>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> >>>>  {
> >>>>  	struct uvc_fh *handle = fh;
> >>>> +	struct uvc_streaming *stream = handle->stream;
> >>>>  	struct uvc_video_chain *chain = handle->chain;
> >>>>  	u8 *buf;
> >>>>  	int ret;
> >>>>  
> >>>> -	ret = uvc_acquire_privileges(handle);
> >>>> -	if (ret < 0)
> >>>> -		return ret;
> >>>> +	if (vb2_is_busy(&stream->queue.queue))
> >>>> +		return -EBUSY;
> >>>>  
> >>>>  	if (chain->selector == NULL ||
> >>>>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> >>>> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> >>>>  	return ret;
> >>>>  }
> >>>>  
> >>>> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> >>>> -		    size_t count, loff_t *ppos)
> >>>> -{
> >>>> -	struct uvc_fh *handle = file->private_data;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> >>>> -	return -EINVAL;
> >>>> -}
> >>>> -
> >>>> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> >>>> -{
> >>>> -	struct uvc_fh *handle = file->private_data;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >>>> -
> >>>> -	return uvc_queue_mmap(&stream->queue, vma);
> >>>> -}
> >>>> -
> >>>> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> >>>> -{
> >>>> -	struct uvc_fh *handle = file->private_data;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >>>> -
> >>>> -	return uvc_queue_poll(&stream->queue, file, wait);
> >>>> -}
> >>>> -
> >>>> -#ifndef CONFIG_MMU
> >>>> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> >>>> -		unsigned long addr, unsigned long len, unsigned long pgoff,
> >>>> -		unsigned long flags)
> >>>> -{
> >>>> -	struct uvc_fh *handle = file->private_data;
> >>>> -	struct uvc_streaming *stream = handle->stream;
> >>>> -
> >>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> >>>> -
> >>>> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> >>>> -}
> >>>> -#endif
> >>>> -
> >>>>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >>>>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> >>>>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> >>>> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> >>>>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> >>>>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> >>>>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> >>>> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
> >>>> -	.vidioc_querybuf = uvc_ioctl_querybuf,
> >>>> -	.vidioc_qbuf = uvc_ioctl_qbuf,
> >>>> -	.vidioc_expbuf = uvc_ioctl_expbuf,
> >>>> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
> >>>> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
> >>>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> >>>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> >>>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> >>>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> >>>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> >>>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> >>>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> >>>>  	.vidioc_streamon = uvc_ioctl_streamon,
> >>>>  	.vidioc_streamoff = uvc_ioctl_streamoff,
> >>>>  	.vidioc_enum_input = uvc_ioctl_enum_input,
> >>>> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> >>>>  #ifdef CONFIG_COMPAT
> >>>>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
> >>>>  #endif
> >>>> -	.read		= uvc_v4l2_read,
> >>>> -	.mmap		= uvc_v4l2_mmap,
> >>>> -	.poll		= uvc_v4l2_poll,
> >>>> +	.mmap		= vb2_fop_mmap,
> >>>> +	.poll		= vb2_fop_poll,
> >>>>  #ifndef CONFIG_MMU
> >>>> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
> >>>> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
> >>>>  #endif
> >>>>  };
> >>>>  
> >>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> >>>> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> >>>> --- a/drivers/media/usb/uvc/uvcvideo.h
> >>>> +++ b/drivers/media/usb/uvc/uvcvideo.h
> >>>> @@ -326,7 +326,10 @@ struct uvc_buffer {
> >>>>  
> >>>>  struct uvc_video_queue {
> >>>>  	struct vb2_queue queue;
> >>>> -	struct mutex mutex;			/* Protects queue */
> >>>> +	struct mutex mutex;			/*
> >>>> +						 * Serializes vb2_queue and
> >>>> +						 * fops
> >>>> +						 */
> >>>>  
> >>>>  	unsigned int flags;
> >>>>  	unsigned int buf_used;
> >>>> @@ -349,7 +352,6 @@ struct uvc_video_chain {
> >>>>  						 * uvc_fh.pending_async_ctrls
> >>>>  						 */
> >>>>  
> >>>> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
> >>>>  	u32 caps;				/* V4L2 chain-wide caps */
> >>>>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
> >>>>  };
> >>>> @@ -619,16 +621,10 @@ struct uvc_device {
> >>>>  	struct uvc_entity *gpio_unit;
> >>>>  };
> >>>>  
> >>>> -enum uvc_handle_state {
> >>>> -	UVC_HANDLE_PASSIVE	= 0,
> >>>> -	UVC_HANDLE_ACTIVE	= 1,
> >>>> -};
> >>>> -
> >>>>  struct uvc_fh {
> >>>>  	struct v4l2_fh vfh;
> >>>>  	struct uvc_video_chain *chain;
> >>>>  	struct uvc_streaming *stream;
> >>>> -	enum uvc_handle_state state;
> >>>>  	unsigned int pending_async_ctrls;
> >>>>  	bool is_streaming;
> >>>>  };
> >>>> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> >>>>  
> >>>>  /* Video buffers queue management. */
> >>>>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >>>> -void uvc_queue_release(struct uvc_video_queue *queue);
> >>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
> >>>> -			struct v4l2_requestbuffers *rb);
> >>>> -int uvc_query_buffer(struct uvc_video_queue *queue,
> >>>> -		     struct v4l2_buffer *v4l2_buf);
> >>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
> >>>> -		       struct v4l2_create_buffers *v4l2_cb);
> >>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
> >>>> -		     struct media_device *mdev,
> >>>> -		     struct v4l2_buffer *v4l2_buf);
> >>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
> >>>> -		      struct v4l2_exportbuffer *exp);
> >>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> >>>> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
> >>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> >>>>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> >>>>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> >>>>  					 struct uvc_buffer *buf);
> >>>>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> >>>>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> >>>> -int uvc_queue_mmap(struct uvc_video_queue *queue,
> >>>> -		   struct vm_area_struct *vma);
> >>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> >>>> -			poll_table *wait);
> >>>> -#ifndef CONFIG_MMU
> >>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> >>>> -					  unsigned long pgoff);
> >>>> -#endif
> >>>> -int uvc_queue_allocated(struct uvc_video_queue *queue);
> >>>>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> >>>>  {
> >>>>  	return vb2_is_streaming(&queue->queue);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Hans Verkuil]

On 6/3/25 10:34, Laurent Pinchart wrote:
> On Tue, Jun 03, 2025 at 10:22:47AM +0200, Hans Verkuil wrote:
>> On 6/3/25 09:46, Laurent Pinchart wrote:
>>> On Mon, Jun 02, 2025 at 09:58:08PM +0200, Hans Verkuil wrote:
>>>> On 02/06/2025 20:31, Laurent Pinchart wrote:
>>>>> On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
>>>>>> From: Hans Verkuil <hans@jjverkuil.nl>
>>>>>>
>>>>>> When uvc was written the vb2 ioctl and file operation helpers didn't exist.
>>>>>>
>>>>>> This patch switches uvc over to those helpers, which removes a lot of
>>>>>> boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
>>>>>
>>>>> How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
>>>>> patch does related to priority is replace the per-chain priority
>>>>> handling with a per-device (as in uvc_device) priority, as the default
>>>>> is to use the prio state from v4l2_device. I think this is actually
>>>>> incorrect, a UVC device can have multiple independent streaming
>>>>> interfaces, so the priority ioctls should no operate on a device-wide
>>>>> prio state. Am I missing something ?
>>>>
>>>> The prio handling is per video_device. So an application that opens
>>>> /dev/videoX can raise the priority on the file handle to prevent other
>>>> applications that open the same video device from making changes.
>>>>
>>>>>> and allows us
>>>>>> to drop the 'privileges' scheme, since that's now handled inside the vb2
>>>>>> helpers.
>>>>>
>>>>> That part is correct. The driver implements a privilege-management
>>>>> system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
>>>>> handlers, as the ioctl handlers didn't exist back then.
>>>>>
>>>>> Please reword the commit message to make this clearer. If the prio
>>>>> change is also desired, it should be split in a separate patch.
>>>>>
>>>>>> This makes it possible for uvc to fix the v4l2-compliance streaming tests:
>>>>>>  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
>>>>>>
>>>>>> This patch introduces a change on behavior on the uvcdriver to be
>>>>>> aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
>>>>>> S_FORMAT do no grant exclusive ownership of the device.
>>>>>
>>>>> There are other changes in behaviour worth noting, some small, some
>>>>> quite substantial. Let's start with the small one: .vidioc_querybuf()
>>>>> now succeeds when the queue is busy. It seems a check may be missing in
>>>>> v4l2-compliance for this.
>>>>
>>>> It is perfectly fine querying buffers even if the queue is busy, it doesn't
>>>> affect streaming.
>>>
>>> I agree, and I'm fine with the change in behaviour (as long as it gets
>>> mentioned in the commit message). My point is that the uvcvideo driver
>>> didn't allow it, and that wasn't caught by v4l2-compliance, so we're
>>> probably missing a test there.
>>
>> I'm not sure there is anything wrong with how uvc behaves w.r.t. priority
>> handling today. So perhaps there is no need for v4l2-compliance to do
>> anything other than what it already does.
> 
> It's not about prio. If you call VIDIOC_QUERYBUF on uvcvideo device that
> is busy due to another process, the call will fail with -EBUSY. The V4L2
> specification doesn't allow that behaviour as far as I understand, and
> other V4L2 drivers happily handle QUERYBUF on a busy queue. This patch
> fixes it, and I think this deserves a v4l2-compliance check.

I'm sorry, I thought this was still about prio handling :-)

Yes, a test should be added: v4l2-test-buffers.cpp, after line 789,
there should be a QUERYBUF test added.

Regards,

	Hans

> 
>> If we just keep the uvc prio code as-is, and v4l2-compliance doesn't complain
>> about that, then I don't see any need to change it.
>>
>>>>> The bigger change is related to locking. See below.
>>>>>
>>>>>> Reviewed-by: Hans de Goede <hansg@kernel.org>
>>>>>> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
>>>>>> Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
>>>>>> Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
>>>>>> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
>>>>>> ---
>>>>>>  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
>>>>>>  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
>>>>>>  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
>>>>>>  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
>>>>>>  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
>>>>>>  5 files changed, 30 insertions(+), 443 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>>>>>> index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
>>>>>> --- a/drivers/media/usb/uvc/uvc_driver.c
>>>>>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>>>>>> @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
>>>>>>  	INIT_LIST_HEAD(&chain->entities);
>>>>>>  	mutex_init(&chain->ctrl_mutex);
>>>>>>  	chain->dev = dev;
>>>>>> -	v4l2_prio_init(&chain->prio);
>>>>>>  
>>>>>>  	return chain;
>>>>>>  }
>>>>>> @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
>>>>>>  		if (!video_is_registered(&stream->vdev))
>>>>>>  			continue;
>>>>>>  
>>>>>> -		/*
>>>>>> -		 * For stream->vdev we follow the same logic as:
>>>>>> -		 * vb2_video_unregister_device().
>>>>>> -		 */
>>>>>> -
>>>>>> -		/* 1. Take a reference to vdev */
>>>>>> -		get_device(&stream->vdev.dev);
>>>>>> -
>>>>>> -		/* 2. Ensure that no new ioctls can be called. */
>>>>>> -		video_unregister_device(&stream->vdev);
>>>>>> -
>>>>>> -		/* 3. Wait for old ioctls to finish. */
>>>>>> -		mutex_lock(&stream->mutex);
>>>>>> -
>>>>>> -		/* 4. Stop streaming. */
>>>>>> -		uvc_queue_release(&stream->queue);
>>>>>> -
>>>>>> -		mutex_unlock(&stream->mutex);
>>>>>> -
>>>>>> -		put_device(&stream->vdev.dev);
>>>>>> -
>>>>>> -		/*
>>>>>> -		 * For stream->meta.vdev we can directly call:
>>>>>> -		 * vb2_video_unregister_device().
>>>>>> -		 */
>>>>>> +		vb2_video_unregister_device(&stream->vdev);
>>>>>>  		vb2_video_unregister_device(&stream->meta.vdev);
>>>>>>  
>>>>>>  		/*
>>>>>> @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
>>>>>>  	vdev->fops = fops;
>>>>>>  	vdev->ioctl_ops = ioctl_ops;
>>>>>>  	vdev->release = uvc_release;
>>>>>> -	vdev->prio = &stream->chain->prio;
>>>>>> +	vdev->queue = &queue->queue;
>>>>>> +	vdev->lock = &queue->mutex;
>>>>>
>>>>> This will cause the ioctl handlers to use queue->mutex for all ioctls
>>>>> (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
>>>>> coarse, that should be mentioned in the commit message.
>>>>>
>>>>>>  	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
>>>>>>  		vdev->vfl_dir = VFL_DIR_TX;
>>>>>>  	else
>>>>>> @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
>>>>>>  		if (stream->intf == intf) {
>>>>>>  			ret = uvc_video_resume(stream, reset);
>>>>>>  			if (ret < 0)
>>>>>> -				uvc_queue_streamoff(&stream->queue,
>>>>>> -						    stream->queue.queue.type);
>>>>>> +				vb2_streamoff(&stream->queue.queue,
>>>>>> +					      stream->queue.queue.type);
>>>>>
>>>>> This doesn't take any lock anymore. Can that be a problem ?
>>>>>
>>>>>>  			return ret;
>>>>>>  		}
>>>>>>  	}
>>>>>> diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
>>>>>> index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
>>>>>> --- a/drivers/media/usb/uvc/uvc_metadata.c
>>>>>> +++ b/drivers/media/usb/uvc/uvc_metadata.c
>>>>>> @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
>>>>>>  	 */
>>>>>>  	mutex_lock(&stream->mutex);
>>>>>
>>>>> Is this lock still needed ? More broadly speaking, what's the remaining
>>>>> purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
>>>>> drop queue->mutex, and use stream->mutex everywhere instead ?
>>>>>
>>>>>>  
>>>>>> -	if (uvc_queue_allocated(&stream->queue))
>>>>>> +	if (vb2_is_busy(&stream->meta.queue.queue))
>>>>>>  		ret = -EBUSY;
>>>>>>  	else
>>>>>>  		stream->meta.format = fmt->dataformat;
>>>>>> @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
>>>>>>  
>>>>>>  	stream->meta.format = V4L2_META_FMT_UVC;
>>>>>>  
>>>>>> -	/*
>>>>>> -	 * The video interface queue uses manual locking and thus does not set
>>>>>> -	 * the queue pointer. Set it manually here.
>>>>>> -	 */
>>>>>> -	vdev->queue = &queue->queue;
>>>>>> -
>>>>>>  	return uvc_register_video_device(dev, stream, vdev, queue,
>>>>>>  					 V4L2_BUF_TYPE_META_CAPTURE,
>>>>>>  					 &uvc_meta_fops, &uvc_meta_ioctl_ops);
>>>>>> diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
>>>>>> index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
>>>>>> --- a/drivers/media/usb/uvc/uvc_queue.c
>>>>>> +++ b/drivers/media/usb/uvc/uvc_queue.c
>>>>>> @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>>>>  	return 0;
>>>>>>  }
>>>>>>  
>>>>>> -void uvc_queue_release(struct uvc_video_queue *queue)
>>>>>> -{
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	vb2_queue_release(&queue->queue);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -}
>>>>>> -
>>>>>> -/* -----------------------------------------------------------------------------
>>>>>> - * V4L2 queue operations
>>>>>> - */
>>>>>> -
>>>>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>>>>> -			struct v4l2_requestbuffers *rb)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_reqbufs(&queue->queue, rb);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret ? ret : rb->count;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_querybuf(&queue->queue, buf);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>>>>> -		       struct v4l2_create_buffers *cb)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_create_bufs(&queue->queue, cb);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>>>>> -		     struct media_device *mdev, struct v4l2_buffer *buf)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_qbuf(&queue->queue, mdev, buf);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>>>>> -		      struct v4l2_exportbuffer *exp)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_expbuf(&queue->queue, exp);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
>>>>>> -		       int nonblocking)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_streamon(&queue->queue, type);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
>>>>>> -{
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_streamoff(&queue->queue, type);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>> -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
>>>>>> -{
>>>>>> -	return vb2_mmap(&queue->queue, vma);
>>>>>> -}
>>>>>> -
>>>>>> -#ifndef CONFIG_MMU
>>>>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>>>>> -		unsigned long pgoff)
>>>>>> -{
>>>>>> -	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
>>>>>> -}
>>>>>> -#endif
>>>>>> -
>>>>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>>>>> -			    poll_table *wait)
>>>>>> -{
>>>>>> -	__poll_t ret;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	ret = vb2_poll(&queue->queue, file, wait);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return ret;
>>>>>> -}
>>>>>> -
>>>>>>  /* -----------------------------------------------------------------------------
>>>>>>   *
>>>>>>   */
>>>>>>  
>>>>>> -/*
>>>>>> - * Check if buffers have been allocated.
>>>>>> - */
>>>>>> -int uvc_queue_allocated(struct uvc_video_queue *queue)
>>>>>> -{
>>>>>> -	int allocated;
>>>>>> -
>>>>>> -	mutex_lock(&queue->mutex);
>>>>>> -	allocated = vb2_is_busy(&queue->queue);
>>>>>> -	mutex_unlock(&queue->mutex);
>>>>>> -
>>>>>> -	return allocated;
>>>>>> -}
>>>>>> -
>>>>>>  /*
>>>>>>   * Cancel the video buffers queue.
>>>>>>   *
>>>>>> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
>>>>>> index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
>>>>>> --- a/drivers/media/usb/uvc/uvc_v4l2.c
>>>>>> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
>>>>>> @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
>>>>>>  	usb_autopm_put_interface(dev->intf);
>>>>>>  }
>>>>>>  
>>>>>> -static int uvc_acquire_privileges(struct uvc_fh *handle);
>>>>>> -
>>>>>>  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
>>>>>>  				      struct uvc_control_mapping *map,
>>>>>>  				      const struct uvc_xu_control_mapping *xmap)
>>>>>> @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>>>>  	const struct uvc_frame *frame;
>>>>>>  	int ret;
>>>>>>  
>>>>>> -	ret = uvc_acquire_privileges(handle);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> -
>>>>>>  	if (fmt->type != stream->type)
>>>>>>  		return -EINVAL;
>>>>>>  
>>>>>> @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
>>>>>>  		return ret;
>>>>>>  
>>>>>>  	mutex_lock(&stream->mutex);
>>>>>> -
>>>>>> -	if (uvc_queue_allocated(&stream->queue)) {
>>>>>> +	if (vb2_is_busy(&stream->queue.queue)) {
>>>>>>  		ret = -EBUSY;
>>>>>>  		goto done;
>>>>>>  	}
>>>>>> @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>>>>  	unsigned int i;
>>>>>>  	int ret;
>>>>>>  
>>>>>> -	ret = uvc_acquire_privileges(handle);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> -
>>>>>>  	if (parm->type != stream->type)
>>>>>>  		return -EINVAL;
>>>>>>  
>>>>>> @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
>>>>>>  	return 0;
>>>>>>  }
>>>>>>  
>>>>>> -/* ------------------------------------------------------------------------
>>>>>> - * Privilege management
>>>>>> - */
>>>>>> -
>>>>>> -/*
>>>>>> - * Privilege management is the multiple-open implementation basis. The current
>>>>>> - * implementation is completely transparent for the end-user and doesn't
>>>>>> - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
>>>>>> - * Those ioctls enable finer control on the device (by making possible for a
>>>>>> - * user to request exclusive access to a device), but are not mature yet.
>>>>>> - * Switching to the V4L2 priority mechanism might be considered in the future
>>>>>> - * if this situation changes.
>>>>>> - *
>>>>>> - * Each open instance of a UVC device can either be in a privileged or
>>>>>> - * unprivileged state. Only a single instance can be in a privileged state at
>>>>>> - * a given time. Trying to perform an operation that requires privileges will
>>>>>> - * automatically acquire the required privileges if possible, or return -EBUSY
>>>>>> - * otherwise. Privileges are dismissed when closing the instance or when
>>>>>> - * freeing the video buffers using VIDIOC_REQBUFS.
>>>>>> - *
>>>>>> - * Operations that require privileges are:
>>>>>> - *
>>>>>> - * - VIDIOC_S_INPUT
>>>>>> - * - VIDIOC_S_PARM
>>>>>> - * - VIDIOC_S_FMT
>>>>>> - * - VIDIOC_CREATE_BUFS
>>>>>> - * - VIDIOC_REQBUFS
>>>>>> - */
>>>>>> -static int uvc_acquire_privileges(struct uvc_fh *handle)
>>>>>> -{
>>>>>> -	/* Always succeed if the handle is already privileged. */
>>>>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>>>>> -		return 0;
>>>>>> -
>>>>>> -	/* Check if the device already has a privileged handle. */
>>>>>> -	if (atomic_inc_return(&handle->stream->active) != 1) {
>>>>>> -		atomic_dec(&handle->stream->active);
>>>>>> -		return -EBUSY;
>>>>>> -	}
>>>>>> -
>>>>>> -	handle->state = UVC_HANDLE_ACTIVE;
>>>>>> -	return 0;
>>>>>> -}
>>>>>> -
>>>>>> -static void uvc_dismiss_privileges(struct uvc_fh *handle)
>>>>>> -{
>>>>>> -	if (handle->state == UVC_HANDLE_ACTIVE)
>>>>>> -		atomic_dec(&handle->stream->active);
>>>>>> -
>>>>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_has_privileges(struct uvc_fh *handle)
>>>>>> -{
>>>>>> -	return handle->state == UVC_HANDLE_ACTIVE;
>>>>>> -}
>>>>>> -
>>>>>>  /* ------------------------------------------------------------------------
>>>>>>   * V4L2 file operations
>>>>>>   */
>>>>>> @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
>>>>>>  	v4l2_fh_add(&handle->vfh);
>>>>>>  	handle->chain = stream->chain;
>>>>>>  	handle->stream = stream;
>>>>>> -	handle->state = UVC_HANDLE_PASSIVE;
>>>>>>  	file->private_data = handle;
>>>>>>  
>>>>>>  	return 0;
>>>>>> @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
>>>>>>  
>>>>>>  	uvc_ctrl_cleanup_fh(handle);
>>>>>>  
>>>>>> -	/* Only free resources if this is a privileged handle. */
>>>>>> -	if (uvc_has_privileges(handle))
>>>>>> -		uvc_queue_release(&stream->queue);
>>>>>> -
>>>>>>  	if (handle->is_streaming)
>>>>>>  		uvc_pm_put(stream->dev);
>>>>>>  
>>>>>>  	/* Release the file handle. */
>>>>>> -	uvc_dismiss_privileges(handle);
>>>>>> -	v4l2_fh_del(&handle->vfh);
>>>>>> -	v4l2_fh_exit(&handle->vfh);
>>>>>> -	kfree(handle);
>>>>>> +	vb2_fop_release(file);
>>>>>>  	file->private_data = NULL;
>>>>>
>>>>> You can drop setting private_data to NULL, it's done by
>>>>> v4l2_fh_release() called by vb2_fop_release().
>>>>>
>>>>>>  
>>>>>>  	return 0;
>>>>>> @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
>>>>>>  	return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
>>>>>>  }
>>>>>>  
>>>>>> -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
>>>>>> -			     struct v4l2_requestbuffers *rb)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	ret = uvc_acquire_privileges(handle);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> -
>>>>>> -	mutex_lock(&stream->mutex);
>>>>>> -	ret = uvc_request_buffers(&stream->queue, rb);
>>>>>> -	mutex_unlock(&stream->mutex);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> -
>>>>>> -	if (ret == 0)
>>>>>> -		uvc_dismiss_privileges(handle);
>>>>>> -
>>>>>> -	return 0;
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_ioctl_querybuf(struct file *file, void *fh,
>>>>>> -			      struct v4l2_buffer *buf)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	return uvc_query_buffer(&stream->queue, buf);
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	return uvc_queue_buffer(&stream->queue,
>>>>>> -				stream->vdev.v4l2_dev->mdev, buf);
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_ioctl_expbuf(struct file *file, void *fh,
>>>>>> -			    struct v4l2_exportbuffer *exp)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	return uvc_export_buffer(&stream->queue, exp);
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	return uvc_dequeue_buffer(&stream->queue, buf,
>>>>>> -				  file->f_flags & O_NONBLOCK);
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
>>>>>> -				  struct v4l2_create_buffers *cb)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = fh;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -	int ret;
>>>>>> -
>>>>>> -	ret = uvc_acquire_privileges(handle);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> -
>>>>>> -	return uvc_create_buffers(&stream->queue, cb);
>>>>>> -}
>>>>>> -
>>>>>>  static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>>>  			      enum v4l2_buf_type type)
>>>>>>  {
>>>>>> @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>>>  	struct uvc_streaming *stream = handle->stream;
>>>>>>  	int ret;
>>>>>>  
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	guard(mutex)(&stream->mutex);
>>>>>> -
>>>>>>  	if (handle->is_streaming)
>>>>>>  		return 0;
>>>>>>  
>>>>>> @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
>>>>>>  	if (ret)
>>>>>>  		return ret;
>>>>>>  
>>>>>> -	ret = uvc_queue_streamon(&stream->queue, type);
>>>>>> +	ret = vb2_ioctl_streamon(file, fh, type);
>>>>>>  	if (ret) {
>>>>>>  		uvc_pm_put(stream->dev);
>>>>>>  		return ret;
>>>>>> @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
>>>>>>  {
>>>>>>  	struct uvc_fh *handle = fh;
>>>>>>  	struct uvc_streaming *stream = handle->stream;
>>>>>> +	int ret;
>>>>>>  
>>>>>> -	if (!uvc_has_privileges(handle))
>>>>>> -		return -EBUSY;
>>>>>> -
>>>>>> -	guard(mutex)(&stream->mutex);
>>>>>> +	ret = vb2_ioctl_streamoff(file, fh, type);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>>>  
>>>>>> -	uvc_queue_streamoff(&stream->queue, type);
>>>>>>  	if (handle->is_streaming) {
>>>>>>  		handle->is_streaming = false;
>>>>>>  		uvc_pm_put(stream->dev);
>>>>>> @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
>>>>>>  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
>>>>>>  {
>>>>>>  	struct uvc_fh *handle = fh;
>>>>>> +	struct uvc_streaming *stream = handle->stream;
>>>>>>  	struct uvc_video_chain *chain = handle->chain;
>>>>>>  	u8 *buf;
>>>>>>  	int ret;
>>>>>>  
>>>>>> -	ret = uvc_acquire_privileges(handle);
>>>>>> -	if (ret < 0)
>>>>>> -		return ret;
>>>>>> +	if (vb2_is_busy(&stream->queue.queue))
>>>>>> +		return -EBUSY;
>>>>>>  
>>>>>>  	if (chain->selector == NULL ||
>>>>>>  	    (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
>>>>>> @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>>>>>>  	return ret;
>>>>>>  }
>>>>>>  
>>>>>> -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
>>>>>> -		    size_t count, loff_t *ppos)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = file->private_data;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
>>>>>> -	return -EINVAL;
>>>>>> -}
>>>>>> -
>>>>>> -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = file->private_data;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>>>> -
>>>>>> -	return uvc_queue_mmap(&stream->queue, vma);
>>>>>> -}
>>>>>> -
>>>>>> -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = file->private_data;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>>>> -
>>>>>> -	return uvc_queue_poll(&stream->queue, file, wait);
>>>>>> -}
>>>>>> -
>>>>>> -#ifndef CONFIG_MMU
>>>>>> -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
>>>>>> -		unsigned long addr, unsigned long len, unsigned long pgoff,
>>>>>> -		unsigned long flags)
>>>>>> -{
>>>>>> -	struct uvc_fh *handle = file->private_data;
>>>>>> -	struct uvc_streaming *stream = handle->stream;
>>>>>> -
>>>>>> -	uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
>>>>>> -
>>>>>> -	return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
>>>>>> -}
>>>>>> -#endif
>>>>>> -
>>>>>>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>>>>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>>>>>>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>>>>>> @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>>>>>>  	.vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
>>>>>>  	.vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
>>>>>>  	.vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
>>>>>> -	.vidioc_reqbufs = uvc_ioctl_reqbufs,
>>>>>> -	.vidioc_querybuf = uvc_ioctl_querybuf,
>>>>>> -	.vidioc_qbuf = uvc_ioctl_qbuf,
>>>>>> -	.vidioc_expbuf = uvc_ioctl_expbuf,
>>>>>> -	.vidioc_dqbuf = uvc_ioctl_dqbuf,
>>>>>> -	.vidioc_create_bufs = uvc_ioctl_create_bufs,
>>>>>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>>>>>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>>>>>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>>>>>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>>>>>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
>>>>>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>>>>>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>>>>>>  	.vidioc_streamon = uvc_ioctl_streamon,
>>>>>>  	.vidioc_streamoff = uvc_ioctl_streamoff,
>>>>>>  	.vidioc_enum_input = uvc_ioctl_enum_input,
>>>>>> @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
>>>>>>  #ifdef CONFIG_COMPAT
>>>>>>  	.compat_ioctl32	= uvc_v4l2_compat_ioctl32,
>>>>>>  #endif
>>>>>> -	.read		= uvc_v4l2_read,
>>>>>> -	.mmap		= uvc_v4l2_mmap,
>>>>>> -	.poll		= uvc_v4l2_poll,
>>>>>> +	.mmap		= vb2_fop_mmap,
>>>>>> +	.poll		= vb2_fop_poll,
>>>>>>  #ifndef CONFIG_MMU
>>>>>> -	.get_unmapped_area = uvc_v4l2_get_unmapped_area,
>>>>>> +	.get_unmapped_area = vb2_fop_get_unmapped_area,
>>>>>>  #endif
>>>>>>  };
>>>>>>  
>>>>>> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
>>>>>> index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
>>>>>> --- a/drivers/media/usb/uvc/uvcvideo.h
>>>>>> +++ b/drivers/media/usb/uvc/uvcvideo.h
>>>>>> @@ -326,7 +326,10 @@ struct uvc_buffer {
>>>>>>  
>>>>>>  struct uvc_video_queue {
>>>>>>  	struct vb2_queue queue;
>>>>>> -	struct mutex mutex;			/* Protects queue */
>>>>>> +	struct mutex mutex;			/*
>>>>>> +						 * Serializes vb2_queue and
>>>>>> +						 * fops
>>>>>> +						 */
>>>>>>  
>>>>>>  	unsigned int flags;
>>>>>>  	unsigned int buf_used;
>>>>>> @@ -349,7 +352,6 @@ struct uvc_video_chain {
>>>>>>  						 * uvc_fh.pending_async_ctrls
>>>>>>  						 */
>>>>>>  
>>>>>> -	struct v4l2_prio_state prio;		/* V4L2 priority state */
>>>>>>  	u32 caps;				/* V4L2 chain-wide caps */
>>>>>>  	u8 ctrl_class_bitmap;			/* Bitmap of valid classes */
>>>>>>  };
>>>>>> @@ -619,16 +621,10 @@ struct uvc_device {
>>>>>>  	struct uvc_entity *gpio_unit;
>>>>>>  };
>>>>>>  
>>>>>> -enum uvc_handle_state {
>>>>>> -	UVC_HANDLE_PASSIVE	= 0,
>>>>>> -	UVC_HANDLE_ACTIVE	= 1,
>>>>>> -};
>>>>>> -
>>>>>>  struct uvc_fh {
>>>>>>  	struct v4l2_fh vfh;
>>>>>>  	struct uvc_video_chain *chain;
>>>>>>  	struct uvc_streaming *stream;
>>>>>> -	enum uvc_handle_state state;
>>>>>>  	unsigned int pending_async_ctrls;
>>>>>>  	bool is_streaming;
>>>>>>  };
>>>>>> @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
>>>>>>  
>>>>>>  /* Video buffers queue management. */
>>>>>>  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>>>> -void uvc_queue_release(struct uvc_video_queue *queue);
>>>>>> -int uvc_request_buffers(struct uvc_video_queue *queue,
>>>>>> -			struct v4l2_requestbuffers *rb);
>>>>>> -int uvc_query_buffer(struct uvc_video_queue *queue,
>>>>>> -		     struct v4l2_buffer *v4l2_buf);
>>>>>> -int uvc_create_buffers(struct uvc_video_queue *queue,
>>>>>> -		       struct v4l2_create_buffers *v4l2_cb);
>>>>>> -int uvc_queue_buffer(struct uvc_video_queue *queue,
>>>>>> -		     struct media_device *mdev,
>>>>>> -		     struct v4l2_buffer *v4l2_buf);
>>>>>> -int uvc_export_buffer(struct uvc_video_queue *queue,
>>>>>> -		      struct v4l2_exportbuffer *exp);
>>>>>> -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
>>>>>> -		       struct v4l2_buffer *v4l2_buf, int nonblocking);
>>>>>> -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>>>> -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
>>>>>>  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
>>>>>>  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
>>>>>>  					 struct uvc_buffer *buf);
>>>>>>  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
>>>>>>  void uvc_queue_buffer_release(struct uvc_buffer *buf);
>>>>>> -int uvc_queue_mmap(struct uvc_video_queue *queue,
>>>>>> -		   struct vm_area_struct *vma);
>>>>>> -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
>>>>>> -			poll_table *wait);
>>>>>> -#ifndef CONFIG_MMU
>>>>>> -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
>>>>>> -					  unsigned long pgoff);
>>>>>> -#endif
>>>>>> -int uvc_queue_allocated(struct uvc_video_queue *queue);
>>>>>>  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
>>>>>>  {
>>>>>>  	return vb2_is_streaming(&queue->queue);
> 

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Laurent Pinchart]

On Mon, Jun 02, 2025 at 09:53:09PM +0200, Ricardo Ribalda wrote:
> On Mon, 2 Jun 2025 at 20:31, Laurent Pinchart wrote:
> > On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> > > From: Hans Verkuil <hans@jjverkuil.nl>
> > >
> > > When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> > >
> > > This patch switches uvc over to those helpers, which removes a lot of
> > > boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> >
> > How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> > patch does related to priority is replace the per-chain priority
> > handling with a per-device (as in uvc_device) priority, as the default
> > is to use the prio state from v4l2_device. I think this is actually
> > incorrect, a UVC device can have multiple independent streaming
> > interfaces, so the priority ioctls should no operate on a device-wide
> > prio state. Am I missing something ?
> 
> You are correct.
> The uvcvideo is the only driver that does not use the prio state from
> v4l2_device and it makes v4l2-core a bit more complicated.
> 
> I have not seen a real use of  VIDIOC_[GS]_PRIORITY, so being a bit
> incorrect in favor of simplicity is probably a good trade-off.
> Anyway it is an easy change to split into a different patch, we can
> have the discussion about prio there.
> 
> > > and allows us
> > > to drop the 'privileges' scheme, since that's now handled inside the vb2
> > > helpers.
> >
> > That part is correct. The driver implements a privilege-management
> > system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> > handlers, as the ioctl handlers didn't exist back then.
> >
> > Please reword the commit message to make this clearer. If the prio
> > change is also desired, it should be split in a separate patch.
> >
> > > This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> > >  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> > >
> > > This patch introduces a change on behavior on the uvcdriver to be
> > > aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> > > S_FORMAT do no grant exclusive ownership of the device.
> >
> > There are other changes in behaviour worth noting, some small, some
> > quite substantial. Let's start with the small one: .vidioc_querybuf()
> > now succeeds when the queue is busy. It seems a check may be missing in
> > v4l2-compliance for this.
> 
> Agree,
> After we land this we can add the check to v4l2-compliance.
> 
> > The bigger change is related to locking. See below.
> >
> > > Reviewed-by: Hans de Goede <hansg@kernel.org>
> > > Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> > > Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> > > Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > ---
> > >  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> > >  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> > >  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> > >  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> > >  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> > >  5 files changed, 30 insertions(+), 443 deletions(-)
> > >
> > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> > >       INIT_LIST_HEAD(&chain->entities);
> > >       mutex_init(&chain->ctrl_mutex);
> > >       chain->dev = dev;
> > > -     v4l2_prio_init(&chain->prio);
> > >
> > >       return chain;
> > >  }
> > > @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> > >               if (!video_is_registered(&stream->vdev))
> > >                       continue;
> > >
> > > -             /*
> > > -              * For stream->vdev we follow the same logic as:
> > > -              * vb2_video_unregister_device().
> > > -              */
> > > -
> > > -             /* 1. Take a reference to vdev */
> > > -             get_device(&stream->vdev.dev);
> > > -
> > > -             /* 2. Ensure that no new ioctls can be called. */
> > > -             video_unregister_device(&stream->vdev);
> > > -
> > > -             /* 3. Wait for old ioctls to finish. */
> > > -             mutex_lock(&stream->mutex);
> > > -
> > > -             /* 4. Stop streaming. */
> > > -             uvc_queue_release(&stream->queue);
> > > -
> > > -             mutex_unlock(&stream->mutex);
> > > -
> > > -             put_device(&stream->vdev.dev);
> > > -
> > > -             /*
> > > -              * For stream->meta.vdev we can directly call:
> > > -              * vb2_video_unregister_device().
> > > -              */
> > > +             vb2_video_unregister_device(&stream->vdev);
> > >               vb2_video_unregister_device(&stream->meta.vdev);
> > >
> > >               /*
> > > @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> > >       vdev->fops = fops;
> > >       vdev->ioctl_ops = ioctl_ops;
> > >       vdev->release = uvc_release;
> > > -     vdev->prio = &stream->chain->prio;
> > > +     vdev->queue = &queue->queue;
> > > +     vdev->lock = &queue->mutex;
> >
> > This will cause the ioctl handlers to use queue->mutex for all ioctls
> > (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> > coarse, that should be mentioned in the commit message.
> >
> > >       if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> > >               vdev->vfl_dir = VFL_DIR_TX;
> > >       else
> > > @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> > >               if (stream->intf == intf) {
> > >                       ret = uvc_video_resume(stream, reset);
> > >                       if (ret < 0)
> > > -                             uvc_queue_streamoff(&stream->queue,
> > > -                                                 stream->queue.queue.type);
> > > +                             vb2_streamoff(&stream->queue.queue,
> > > +                                           stream->queue.queue.type);
> >
> > This doesn't take any lock anymore. Can that be a problem ?
> 
> ack
> Probably better to keep the same lock pattern as before. I am adding
> mutex_lock/unlock
> 
> > >                       return ret;
> > >               }
> > >       }
> > > diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> > > index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> > > --- a/drivers/media/usb/uvc/uvc_metadata.c
> > > +++ b/drivers/media/usb/uvc/uvc_metadata.c
> > > @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> > >        */
> > >       mutex_lock(&stream->mutex);
> >
> > Is this lock still needed ? More broadly speaking, what's the remaining
> > purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> > drop queue->mutex, and use stream->mutex everywhere instead ?
> 
> Good question, this is the first thing that I tried, and there are
> plenty of nested locking that are wrong:
> lock(stream->mutex)
>   lock(stream->muex)
> 
> It is probably fixable, but we can do that as a follow-up patch.

The current locking scheme was designed with two locks, to separate
locking of the buffer-related ioctls from the other ioctls, the same way
that the V4L2 core has a video_device lock and a vb2_queue lock. We
could keep the same design and move to using separate video_device and
vb2_queue locks, but that's not what this patch does. I'm OK with
switching to a single lock as I can't provide compelling evidence that
two locks significantly improve performance (do they ever, or should
V4L2 drop that ?) with uvcvideo at the moment, but I'd like the locking
scheme to remain clean and understandable.

> > >
> > > -     if (uvc_queue_allocated(&stream->queue))
> > > +     if (vb2_is_busy(&stream->meta.queue.queue))
> > >               ret = -EBUSY;
> > >       else
> > >               stream->meta.format = fmt->dataformat;
> > > @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> > >
> > >       stream->meta.format = V4L2_META_FMT_UVC;
> > >
> > > -     /*
> > > -      * The video interface queue uses manual locking and thus does not set
> > > -      * the queue pointer. Set it manually here.
> > > -      */
> > > -     vdev->queue = &queue->queue;
> > > -
> > >       return uvc_register_video_device(dev, stream, vdev, queue,
> > >                                        V4L2_BUF_TYPE_META_CAPTURE,
> > >                                        &uvc_meta_fops, &uvc_meta_ioctl_ops);
> > > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > > index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> > > --- a/drivers/media/usb/uvc/uvc_queue.c
> > > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > > @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > >       return 0;
> > >  }
> > >
> > > -void uvc_queue_release(struct uvc_video_queue *queue)
> > > -{
> > > -     mutex_lock(&queue->mutex);
> > > -     vb2_queue_release(&queue->queue);
> > > -     mutex_unlock(&queue->mutex);
> > > -}
> > > -
> > > -/* -----------------------------------------------------------------------------
> > > - * V4L2 queue operations
> > > - */
> > > -
> > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > -                     struct v4l2_requestbuffers *rb)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_reqbufs(&queue->queue, rb);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret ? ret : rb->count;
> > > -}
> > > -
> > > -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_querybuf(&queue->queue, buf);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > -                    struct v4l2_create_buffers *cb)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_create_bufs(&queue->queue, cb);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > -                  struct media_device *mdev, struct v4l2_buffer *buf)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_qbuf(&queue->queue, mdev, buf);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > -                   struct v4l2_exportbuffer *exp)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_expbuf(&queue->queue, exp);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> > > -                    int nonblocking)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_streamon(&queue->queue, type);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > -{
> > > -     int ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_streamoff(&queue->queue, type);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > > -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> > > -{
> > > -     return vb2_mmap(&queue->queue, vma);
> > > -}
> > > -
> > > -#ifndef CONFIG_MMU
> > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > -             unsigned long pgoff)
> > > -{
> > > -     return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> > > -}
> > > -#endif
> > > -
> > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > -                         poll_table *wait)
> > > -{
> > > -     __poll_t ret;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     ret = vb2_poll(&queue->queue, file, wait);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return ret;
> > > -}
> > > -
> > >  /* -----------------------------------------------------------------------------
> > >   *
> > >   */
> > >
> > > -/*
> > > - * Check if buffers have been allocated.
> > > - */
> > > -int uvc_queue_allocated(struct uvc_video_queue *queue)
> > > -{
> > > -     int allocated;
> > > -
> > > -     mutex_lock(&queue->mutex);
> > > -     allocated = vb2_is_busy(&queue->queue);
> > > -     mutex_unlock(&queue->mutex);
> > > -
> > > -     return allocated;
> > > -}
> > > -
> > >  /*
> > >   * Cancel the video buffers queue.
> > >   *
> > > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > > index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> > > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > > @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> > >       usb_autopm_put_interface(dev->intf);
> > >  }
> > >
> > > -static int uvc_acquire_privileges(struct uvc_fh *handle);
> > > -
> > >  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> > >                                     struct uvc_control_mapping *map,
> > >                                     const struct uvc_xu_control_mapping *xmap)
> > > @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > >       const struct uvc_frame *frame;
> > >       int ret;
> > >
> > > -     ret = uvc_acquire_privileges(handle);
> > > -     if (ret < 0)
> > > -             return ret;
> > > -
> > >       if (fmt->type != stream->type)
> > >               return -EINVAL;
> > >
> > > @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > >               return ret;
> > >
> > >       mutex_lock(&stream->mutex);
> > > -
> > > -     if (uvc_queue_allocated(&stream->queue)) {
> > > +     if (vb2_is_busy(&stream->queue.queue)) {
> > >               ret = -EBUSY;
> > >               goto done;
> > >       }
> > > @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > >       unsigned int i;
> > >       int ret;
> > >
> > > -     ret = uvc_acquire_privileges(handle);
> > > -     if (ret < 0)
> > > -             return ret;
> > > -
> > >       if (parm->type != stream->type)
> > >               return -EINVAL;
> > >
> > > @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > >       return 0;
> > >  }
> > >
> > > -/* ------------------------------------------------------------------------
> > > - * Privilege management
> > > - */
> > > -
> > > -/*
> > > - * Privilege management is the multiple-open implementation basis. The current
> > > - * implementation is completely transparent for the end-user and doesn't
> > > - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> > > - * Those ioctls enable finer control on the device (by making possible for a
> > > - * user to request exclusive access to a device), but are not mature yet.
> > > - * Switching to the V4L2 priority mechanism might be considered in the future
> > > - * if this situation changes.
> > > - *
> > > - * Each open instance of a UVC device can either be in a privileged or
> > > - * unprivileged state. Only a single instance can be in a privileged state at
> > > - * a given time. Trying to perform an operation that requires privileges will
> > > - * automatically acquire the required privileges if possible, or return -EBUSY
> > > - * otherwise. Privileges are dismissed when closing the instance or when
> > > - * freeing the video buffers using VIDIOC_REQBUFS.
> > > - *
> > > - * Operations that require privileges are:
> > > - *
> > > - * - VIDIOC_S_INPUT
> > > - * - VIDIOC_S_PARM
> > > - * - VIDIOC_S_FMT
> > > - * - VIDIOC_CREATE_BUFS
> > > - * - VIDIOC_REQBUFS
> > > - */
> > > -static int uvc_acquire_privileges(struct uvc_fh *handle)
> > > -{
> > > -     /* Always succeed if the handle is already privileged. */
> > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > -             return 0;
> > > -
> > > -     /* Check if the device already has a privileged handle. */
> > > -     if (atomic_inc_return(&handle->stream->active) != 1) {
> > > -             atomic_dec(&handle->stream->active);
> > > -             return -EBUSY;
> > > -     }
> > > -
> > > -     handle->state = UVC_HANDLE_ACTIVE;
> > > -     return 0;
> > > -}
> > > -
> > > -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> > > -{
> > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > -             atomic_dec(&handle->stream->active);
> > > -
> > > -     handle->state = UVC_HANDLE_PASSIVE;
> > > -}
> > > -
> > > -static int uvc_has_privileges(struct uvc_fh *handle)
> > > -{
> > > -     return handle->state == UVC_HANDLE_ACTIVE;
> > > -}
> > > -
> > >  /* ------------------------------------------------------------------------
> > >   * V4L2 file operations
> > >   */
> > > @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> > >       v4l2_fh_add(&handle->vfh);
> > >       handle->chain = stream->chain;
> > >       handle->stream = stream;
> > > -     handle->state = UVC_HANDLE_PASSIVE;
> > >       file->private_data = handle;
> > >
> > >       return 0;
> > > @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> > >
> > >       uvc_ctrl_cleanup_fh(handle);
> > >
> > > -     /* Only free resources if this is a privileged handle. */
> > > -     if (uvc_has_privileges(handle))
> > > -             uvc_queue_release(&stream->queue);
> > > -
> > >       if (handle->is_streaming)
> > >               uvc_pm_put(stream->dev);
> > >
> > >       /* Release the file handle. */
> > > -     uvc_dismiss_privileges(handle);
> > > -     v4l2_fh_del(&handle->vfh);
> > > -     v4l2_fh_exit(&handle->vfh);
> > > -     kfree(handle);
> > > +     vb2_fop_release(file);
> > >       file->private_data = NULL;
> >
> > You can drop setting private_data to NULL, it's done by
> > v4l2_fh_release() called by vb2_fop_release().
> 
> ack
> 
> > >
> > >       return 0;
> > > @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> > >       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> > >  }
> > >
> > > -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> > > -                          struct v4l2_requestbuffers *rb)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -     int ret;
> > > -
> > > -     ret = uvc_acquire_privileges(handle);
> > > -     if (ret < 0)
> > > -             return ret;
> > > -
> > > -     mutex_lock(&stream->mutex);
> > > -     ret = uvc_request_buffers(&stream->queue, rb);
> > > -     mutex_unlock(&stream->mutex);
> > > -     if (ret < 0)
> > > -             return ret;
> > > -
> > > -     if (ret == 0)
> > > -             uvc_dismiss_privileges(handle);
> > > -
> > > -     return 0;
> > > -}
> > > -
> > > -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> > > -                           struct v4l2_buffer *buf)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     return uvc_query_buffer(&stream->queue, buf);
> > > -}
> > > -
> > > -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     return uvc_queue_buffer(&stream->queue,
> > > -                             stream->vdev.v4l2_dev->mdev, buf);
> > > -}
> > > -
> > > -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> > > -                         struct v4l2_exportbuffer *exp)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     return uvc_export_buffer(&stream->queue, exp);
> > > -}
> > > -
> > > -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     return uvc_dequeue_buffer(&stream->queue, buf,
> > > -                               file->f_flags & O_NONBLOCK);
> > > -}
> > > -
> > > -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> > > -                               struct v4l2_create_buffers *cb)
> > > -{
> > > -     struct uvc_fh *handle = fh;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -     int ret;
> > > -
> > > -     ret = uvc_acquire_privileges(handle);
> > > -     if (ret < 0)
> > > -             return ret;
> > > -
> > > -     return uvc_create_buffers(&stream->queue, cb);
> > > -}
> > > -
> > >  static int uvc_ioctl_streamon(struct file *file, void *fh,
> > >                             enum v4l2_buf_type type)
> > >  {
> > > @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > >       struct uvc_streaming *stream = handle->stream;
> > >       int ret;
> > >
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     guard(mutex)(&stream->mutex);
> > > -
> > >       if (handle->is_streaming)
> > >               return 0;
> > >
> > > @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > >       if (ret)
> > >               return ret;
> > >
> > > -     ret = uvc_queue_streamon(&stream->queue, type);
> > > +     ret = vb2_ioctl_streamon(file, fh, type);
> > >       if (ret) {
> > >               uvc_pm_put(stream->dev);
> > >               return ret;
> > > @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> > >  {
> > >       struct uvc_fh *handle = fh;
> > >       struct uvc_streaming *stream = handle->stream;
> > > +     int ret;
> > >
> > > -     if (!uvc_has_privileges(handle))
> > > -             return -EBUSY;
> > > -
> > > -     guard(mutex)(&stream->mutex);
> > > +     ret = vb2_ioctl_streamoff(file, fh, type);
> > > +     if (ret)
> > > +             return ret;
> > >
> > > -     uvc_queue_streamoff(&stream->queue, type);
> > >       if (handle->is_streaming) {
> > >               handle->is_streaming = false;
> > >               uvc_pm_put(stream->dev);
> > > @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> > >  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> > >  {
> > >       struct uvc_fh *handle = fh;
> > > +     struct uvc_streaming *stream = handle->stream;
> > >       struct uvc_video_chain *chain = handle->chain;
> > >       u8 *buf;
> > >       int ret;
> > >
> > > -     ret = uvc_acquire_privileges(handle);
> > > -     if (ret < 0)
> > > -             return ret;
> > > +     if (vb2_is_busy(&stream->queue.queue))
> > > +             return -EBUSY;
> > >
> > >       if (chain->selector == NULL ||
> > >           (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> > > @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> > >       return ret;
> > >  }
> > >
> > > -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> > > -                 size_t count, loff_t *ppos)
> > > -{
> > > -     struct uvc_fh *handle = file->private_data;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> > > -     return -EINVAL;
> > > -}
> > > -
> > > -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> > > -{
> > > -     struct uvc_fh *handle = file->private_data;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > -
> > > -     return uvc_queue_mmap(&stream->queue, vma);
> > > -}
> > > -
> > > -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> > > -{
> > > -     struct uvc_fh *handle = file->private_data;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > -
> > > -     return uvc_queue_poll(&stream->queue, file, wait);
> > > -}
> > > -
> > > -#ifndef CONFIG_MMU
> > > -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> > > -             unsigned long addr, unsigned long len, unsigned long pgoff,
> > > -             unsigned long flags)
> > > -{
> > > -     struct uvc_fh *handle = file->private_data;
> > > -     struct uvc_streaming *stream = handle->stream;
> > > -
> > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > -
> > > -     return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> > > -}
> > > -#endif
> > > -
> > >  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > >       .vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> > >       .vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> > > @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > >       .vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> > >       .vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> > >       .vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> > > -     .vidioc_reqbufs = uvc_ioctl_reqbufs,
> > > -     .vidioc_querybuf = uvc_ioctl_querybuf,
> > > -     .vidioc_qbuf = uvc_ioctl_qbuf,
> > > -     .vidioc_expbuf = uvc_ioctl_expbuf,
> > > -     .vidioc_dqbuf = uvc_ioctl_dqbuf,
> > > -     .vidioc_create_bufs = uvc_ioctl_create_bufs,
> > > +     .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > > +     .vidioc_querybuf = vb2_ioctl_querybuf,
> > > +     .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> > > +     .vidioc_qbuf = vb2_ioctl_qbuf,
> > > +     .vidioc_expbuf = vb2_ioctl_expbuf,
> > > +     .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > > +     .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > >       .vidioc_streamon = uvc_ioctl_streamon,
> > >       .vidioc_streamoff = uvc_ioctl_streamoff,
> > >       .vidioc_enum_input = uvc_ioctl_enum_input,
> > > @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> > >  #ifdef CONFIG_COMPAT
> > >       .compat_ioctl32 = uvc_v4l2_compat_ioctl32,
> > >  #endif
> > > -     .read           = uvc_v4l2_read,
> > > -     .mmap           = uvc_v4l2_mmap,
> > > -     .poll           = uvc_v4l2_poll,
> > > +     .mmap           = vb2_fop_mmap,
> > > +     .poll           = vb2_fop_poll,
> > >  #ifndef CONFIG_MMU
> > > -     .get_unmapped_area = uvc_v4l2_get_unmapped_area,
> > > +     .get_unmapped_area = vb2_fop_get_unmapped_area,
> > >  #endif
> > >  };
> > >
> > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > @@ -326,7 +326,10 @@ struct uvc_buffer {
> > >
> > >  struct uvc_video_queue {
> > >       struct vb2_queue queue;
> > > -     struct mutex mutex;                     /* Protects queue */
> > > +     struct mutex mutex;                     /*
> > > +                                              * Serializes vb2_queue and
> > > +                                              * fops
> > > +                                              */
> > >
> > >       unsigned int flags;
> > >       unsigned int buf_used;
> > > @@ -349,7 +352,6 @@ struct uvc_video_chain {
> > >                                                * uvc_fh.pending_async_ctrls
> > >                                                */
> > >
> > > -     struct v4l2_prio_state prio;            /* V4L2 priority state */
> > >       u32 caps;                               /* V4L2 chain-wide caps */
> > >       u8 ctrl_class_bitmap;                   /* Bitmap of valid classes */
> > >  };
> > > @@ -619,16 +621,10 @@ struct uvc_device {
> > >       struct uvc_entity *gpio_unit;
> > >  };
> > >
> > > -enum uvc_handle_state {
> > > -     UVC_HANDLE_PASSIVE      = 0,
> > > -     UVC_HANDLE_ACTIVE       = 1,
> > > -};
> > > -
> > >  struct uvc_fh {
> > >       struct v4l2_fh vfh;
> > >       struct uvc_video_chain *chain;
> > >       struct uvc_streaming *stream;
> > > -     enum uvc_handle_state state;
> > >       unsigned int pending_async_ctrls;
> > >       bool is_streaming;
> > >  };
> > > @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> > >
> > >  /* Video buffers queue management. */
> > >  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > -void uvc_queue_release(struct uvc_video_queue *queue);
> > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > -                     struct v4l2_requestbuffers *rb);
> > > -int uvc_query_buffer(struct uvc_video_queue *queue,
> > > -                  struct v4l2_buffer *v4l2_buf);
> > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > -                    struct v4l2_create_buffers *v4l2_cb);
> > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > -                  struct media_device *mdev,
> > > -                  struct v4l2_buffer *v4l2_buf);
> > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > -                   struct v4l2_exportbuffer *exp);
> > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> > > -                    struct v4l2_buffer *v4l2_buf, int nonblocking);
> > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > >  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> > >  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> > >                                        struct uvc_buffer *buf);
> > >  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> > >  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> > > -int uvc_queue_mmap(struct uvc_video_queue *queue,
> > > -                struct vm_area_struct *vma);
> > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > -                     poll_table *wait);
> > > -#ifndef CONFIG_MMU
> > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > -                                       unsigned long pgoff);
> > > -#endif
> > > -int uvc_queue_allocated(struct uvc_video_queue *queue);
> > >  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> > >  {
> > >       return vb2_is_streaming(&queue->queue);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Ricardo Ribalda]

Hi Laurent

On Tue, 3 Jun 2025 at 10:49, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> On Mon, Jun 02, 2025 at 09:53:09PM +0200, Ricardo Ribalda wrote:
> > On Mon, 2 Jun 2025 at 20:31, Laurent Pinchart wrote:
> > > On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> > > > From: Hans Verkuil <hans@jjverkuil.nl>
> > > >
> > > > When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> > > >
> > > > This patch switches uvc over to those helpers, which removes a lot of
> > > > boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> > >
> > > How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> > > patch does related to priority is replace the per-chain priority
> > > handling with a per-device (as in uvc_device) priority, as the default
> > > is to use the prio state from v4l2_device. I think this is actually
> > > incorrect, a UVC device can have multiple independent streaming
> > > interfaces, so the priority ioctls should no operate on a device-wide
> > > prio state. Am I missing something ?
> >
> > You are correct.
> > The uvcvideo is the only driver that does not use the prio state from
> > v4l2_device and it makes v4l2-core a bit more complicated.
> >
> > I have not seen a real use of  VIDIOC_[GS]_PRIORITY, so being a bit
> > incorrect in favor of simplicity is probably a good trade-off.
> > Anyway it is an easy change to split into a different patch, we can
> > have the discussion about prio there.
> >
> > > > and allows us
> > > > to drop the 'privileges' scheme, since that's now handled inside the vb2
> > > > helpers.
> > >
> > > That part is correct. The driver implements a privilege-management
> > > system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> > > handlers, as the ioctl handlers didn't exist back then.
> > >
> > > Please reword the commit message to make this clearer. If the prio
> > > change is also desired, it should be split in a separate patch.
> > >
> > > > This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> > > >  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> > > >
> > > > This patch introduces a change on behavior on the uvcdriver to be
> > > > aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> > > > S_FORMAT do no grant exclusive ownership of the device.
> > >
> > > There are other changes in behaviour worth noting, some small, some
> > > quite substantial. Let's start with the small one: .vidioc_querybuf()
> > > now succeeds when the queue is busy. It seems a check may be missing in
> > > v4l2-compliance for this.
> >
> > Agree,
> > After we land this we can add the check to v4l2-compliance.
> >
> > > The bigger change is related to locking. See below.
> > >
> > > > Reviewed-by: Hans de Goede <hansg@kernel.org>
> > > > Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> > > > Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> > > > Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > ---
> > > >  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> > > >  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> > > >  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> > > >  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> > > >  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> > > >  5 files changed, 30 insertions(+), 443 deletions(-)
> > > >
> > > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > > index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> > > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > > @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> > > >       INIT_LIST_HEAD(&chain->entities);
> > > >       mutex_init(&chain->ctrl_mutex);
> > > >       chain->dev = dev;
> > > > -     v4l2_prio_init(&chain->prio);
> > > >
> > > >       return chain;
> > > >  }
> > > > @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> > > >               if (!video_is_registered(&stream->vdev))
> > > >                       continue;
> > > >
> > > > -             /*
> > > > -              * For stream->vdev we follow the same logic as:
> > > > -              * vb2_video_unregister_device().
> > > > -              */
> > > > -
> > > > -             /* 1. Take a reference to vdev */
> > > > -             get_device(&stream->vdev.dev);
> > > > -
> > > > -             /* 2. Ensure that no new ioctls can be called. */
> > > > -             video_unregister_device(&stream->vdev);
> > > > -
> > > > -             /* 3. Wait for old ioctls to finish. */
> > > > -             mutex_lock(&stream->mutex);
> > > > -
> > > > -             /* 4. Stop streaming. */
> > > > -             uvc_queue_release(&stream->queue);
> > > > -
> > > > -             mutex_unlock(&stream->mutex);
> > > > -
> > > > -             put_device(&stream->vdev.dev);
> > > > -
> > > > -             /*
> > > > -              * For stream->meta.vdev we can directly call:
> > > > -              * vb2_video_unregister_device().
> > > > -              */
> > > > +             vb2_video_unregister_device(&stream->vdev);
> > > >               vb2_video_unregister_device(&stream->meta.vdev);
> > > >
> > > >               /*
> > > > @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> > > >       vdev->fops = fops;
> > > >       vdev->ioctl_ops = ioctl_ops;
> > > >       vdev->release = uvc_release;
> > > > -     vdev->prio = &stream->chain->prio;
> > > > +     vdev->queue = &queue->queue;
> > > > +     vdev->lock = &queue->mutex;
> > >
> > > This will cause the ioctl handlers to use queue->mutex for all ioctls
> > > (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> > > coarse, that should be mentioned in the commit message.
> > >
> > > >       if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> > > >               vdev->vfl_dir = VFL_DIR_TX;
> > > >       else
> > > > @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> > > >               if (stream->intf == intf) {
> > > >                       ret = uvc_video_resume(stream, reset);
> > > >                       if (ret < 0)
> > > > -                             uvc_queue_streamoff(&stream->queue,
> > > > -                                                 stream->queue.queue.type);
> > > > +                             vb2_streamoff(&stream->queue.queue,
> > > > +                                           stream->queue.queue.type);
> > >
> > > This doesn't take any lock anymore. Can that be a problem ?
> >
> > ack
> > Probably better to keep the same lock pattern as before. I am adding
> > mutex_lock/unlock
> >
> > > >                       return ret;
> > > >               }
> > > >       }
> > > > diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> > > > index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> > > > --- a/drivers/media/usb/uvc/uvc_metadata.c
> > > > +++ b/drivers/media/usb/uvc/uvc_metadata.c
> > > > @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> > > >        */
> > > >       mutex_lock(&stream->mutex);
> > >
> > > Is this lock still needed ? More broadly speaking, what's the remaining
> > > purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> > > drop queue->mutex, and use stream->mutex everywhere instead ?
> >
> > Good question, this is the first thing that I tried, and there are
> > plenty of nested locking that are wrong:
> > lock(stream->mutex)
> >   lock(stream->muex)
> >
> > It is probably fixable, but we can do that as a follow-up patch.
>
> The current locking scheme was designed with two locks, to separate
> locking of the buffer-related ioctls from the other ioctls, the same way
> that the V4L2 core has a video_device lock and a vb2_queue lock. We
> could keep the same design and move to using separate video_device and
> vb2_queue locks, but that's not what this patch does. I'm OK with
> switching to a single lock as I can't provide compelling evidence that
> two locks significantly improve performance (do they ever, or should
> V4L2 drop that ?) with uvcvideo at the moment, but I'd like the locking
> scheme to remain clean and understandable.

I agree with your goal of having a single lock. The question is how to
reach that goal.

I think it is easier/better to do it in two steps:
1) Land this set, where the queue->mutex locks more ioctls than
before, and we keep the stream->mutex
2) Remove one of the mutex.

My reasons are:
- You, HdG, HansV  and I are familiar with the current change and have
already reviewed it.
- Completely refactoring the locking in the same patch will make the
code more difficult to review.
- There are other patchsets that conflict with this set.
- HansV expressed that he wants this addressed with priority.
- The patch fixes v4l2-compliance.
- The patch simplifies the code.

I will look into the new locking the same way that I have been looking
into other housekeeping changes in the uvc driver. But I do not
believe that we should block the development for this.

Regards!


>
> > > >
> > > > -     if (uvc_queue_allocated(&stream->queue))
> > > > +     if (vb2_is_busy(&stream->meta.queue.queue))
> > > >               ret = -EBUSY;
> > > >       else
> > > >               stream->meta.format = fmt->dataformat;
> > > > @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> > > >
> > > >       stream->meta.format = V4L2_META_FMT_UVC;
> > > >
> > > > -     /*
> > > > -      * The video interface queue uses manual locking and thus does not set
> > > > -      * the queue pointer. Set it manually here.
> > > > -      */
> > > > -     vdev->queue = &queue->queue;
> > > > -
> > > >       return uvc_register_video_device(dev, stream, vdev, queue,
> > > >                                        V4L2_BUF_TYPE_META_CAPTURE,
> > > >                                        &uvc_meta_fops, &uvc_meta_ioctl_ops);
> > > > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > > > index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> > > > --- a/drivers/media/usb/uvc/uvc_queue.c
> > > > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > > > @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > >       return 0;
> > > >  }
> > > >
> > > > -void uvc_queue_release(struct uvc_video_queue *queue)
> > > > -{
> > > > -     mutex_lock(&queue->mutex);
> > > > -     vb2_queue_release(&queue->queue);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -}
> > > > -
> > > > -/* -----------------------------------------------------------------------------
> > > > - * V4L2 queue operations
> > > > - */
> > > > -
> > > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > > -                     struct v4l2_requestbuffers *rb)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_reqbufs(&queue->queue, rb);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret ? ret : rb->count;
> > > > -}
> > > > -
> > > > -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_querybuf(&queue->queue, buf);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > > -                    struct v4l2_create_buffers *cb)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_create_bufs(&queue->queue, cb);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > > -                  struct media_device *mdev, struct v4l2_buffer *buf)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_qbuf(&queue->queue, mdev, buf);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > > -                   struct v4l2_exportbuffer *exp)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_expbuf(&queue->queue, exp);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> > > > -                    int nonblocking)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_streamon(&queue->queue, type);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > > -{
> > > > -     int ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_streamoff(&queue->queue, type);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > > -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> > > > -{
> > > > -     return vb2_mmap(&queue->queue, vma);
> > > > -}
> > > > -
> > > > -#ifndef CONFIG_MMU
> > > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > > -             unsigned long pgoff)
> > > > -{
> > > > -     return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> > > > -}
> > > > -#endif
> > > > -
> > > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > > -                         poll_table *wait)
> > > > -{
> > > > -     __poll_t ret;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     ret = vb2_poll(&queue->queue, file, wait);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return ret;
> > > > -}
> > > > -
> > > >  /* -----------------------------------------------------------------------------
> > > >   *
> > > >   */
> > > >
> > > > -/*
> > > > - * Check if buffers have been allocated.
> > > > - */
> > > > -int uvc_queue_allocated(struct uvc_video_queue *queue)
> > > > -{
> > > > -     int allocated;
> > > > -
> > > > -     mutex_lock(&queue->mutex);
> > > > -     allocated = vb2_is_busy(&queue->queue);
> > > > -     mutex_unlock(&queue->mutex);
> > > > -
> > > > -     return allocated;
> > > > -}
> > > > -
> > > >  /*
> > > >   * Cancel the video buffers queue.
> > > >   *
> > > > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > > > index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> > > > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > > > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > > > @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> > > >       usb_autopm_put_interface(dev->intf);
> > > >  }
> > > >
> > > > -static int uvc_acquire_privileges(struct uvc_fh *handle);
> > > > -
> > > >  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> > > >                                     struct uvc_control_mapping *map,
> > > >                                     const struct uvc_xu_control_mapping *xmap)
> > > > @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > > >       const struct uvc_frame *frame;
> > > >       int ret;
> > > >
> > > > -     ret = uvc_acquire_privileges(handle);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > -
> > > >       if (fmt->type != stream->type)
> > > >               return -EINVAL;
> > > >
> > > > @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > > >               return ret;
> > > >
> > > >       mutex_lock(&stream->mutex);
> > > > -
> > > > -     if (uvc_queue_allocated(&stream->queue)) {
> > > > +     if (vb2_is_busy(&stream->queue.queue)) {
> > > >               ret = -EBUSY;
> > > >               goto done;
> > > >       }
> > > > @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > > >       unsigned int i;
> > > >       int ret;
> > > >
> > > > -     ret = uvc_acquire_privileges(handle);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > -
> > > >       if (parm->type != stream->type)
> > > >               return -EINVAL;
> > > >
> > > > @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > > >       return 0;
> > > >  }
> > > >
> > > > -/* ------------------------------------------------------------------------
> > > > - * Privilege management
> > > > - */
> > > > -
> > > > -/*
> > > > - * Privilege management is the multiple-open implementation basis. The current
> > > > - * implementation is completely transparent for the end-user and doesn't
> > > > - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> > > > - * Those ioctls enable finer control on the device (by making possible for a
> > > > - * user to request exclusive access to a device), but are not mature yet.
> > > > - * Switching to the V4L2 priority mechanism might be considered in the future
> > > > - * if this situation changes.
> > > > - *
> > > > - * Each open instance of a UVC device can either be in a privileged or
> > > > - * unprivileged state. Only a single instance can be in a privileged state at
> > > > - * a given time. Trying to perform an operation that requires privileges will
> > > > - * automatically acquire the required privileges if possible, or return -EBUSY
> > > > - * otherwise. Privileges are dismissed when closing the instance or when
> > > > - * freeing the video buffers using VIDIOC_REQBUFS.
> > > > - *
> > > > - * Operations that require privileges are:
> > > > - *
> > > > - * - VIDIOC_S_INPUT
> > > > - * - VIDIOC_S_PARM
> > > > - * - VIDIOC_S_FMT
> > > > - * - VIDIOC_CREATE_BUFS
> > > > - * - VIDIOC_REQBUFS
> > > > - */
> > > > -static int uvc_acquire_privileges(struct uvc_fh *handle)
> > > > -{
> > > > -     /* Always succeed if the handle is already privileged. */
> > > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > > -             return 0;
> > > > -
> > > > -     /* Check if the device already has a privileged handle. */
> > > > -     if (atomic_inc_return(&handle->stream->active) != 1) {
> > > > -             atomic_dec(&handle->stream->active);
> > > > -             return -EBUSY;
> > > > -     }
> > > > -
> > > > -     handle->state = UVC_HANDLE_ACTIVE;
> > > > -     return 0;
> > > > -}
> > > > -
> > > > -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> > > > -{
> > > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > > -             atomic_dec(&handle->stream->active);
> > > > -
> > > > -     handle->state = UVC_HANDLE_PASSIVE;
> > > > -}
> > > > -
> > > > -static int uvc_has_privileges(struct uvc_fh *handle)
> > > > -{
> > > > -     return handle->state == UVC_HANDLE_ACTIVE;
> > > > -}
> > > > -
> > > >  /* ------------------------------------------------------------------------
> > > >   * V4L2 file operations
> > > >   */
> > > > @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> > > >       v4l2_fh_add(&handle->vfh);
> > > >       handle->chain = stream->chain;
> > > >       handle->stream = stream;
> > > > -     handle->state = UVC_HANDLE_PASSIVE;
> > > >       file->private_data = handle;
> > > >
> > > >       return 0;
> > > > @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> > > >
> > > >       uvc_ctrl_cleanup_fh(handle);
> > > >
> > > > -     /* Only free resources if this is a privileged handle. */
> > > > -     if (uvc_has_privileges(handle))
> > > > -             uvc_queue_release(&stream->queue);
> > > > -
> > > >       if (handle->is_streaming)
> > > >               uvc_pm_put(stream->dev);
> > > >
> > > >       /* Release the file handle. */
> > > > -     uvc_dismiss_privileges(handle);
> > > > -     v4l2_fh_del(&handle->vfh);
> > > > -     v4l2_fh_exit(&handle->vfh);
> > > > -     kfree(handle);
> > > > +     vb2_fop_release(file);
> > > >       file->private_data = NULL;
> > >
> > > You can drop setting private_data to NULL, it's done by
> > > v4l2_fh_release() called by vb2_fop_release().
> >
> > ack
> >
> > > >
> > > >       return 0;
> > > > @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> > > >       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> > > >  }
> > > >
> > > > -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> > > > -                          struct v4l2_requestbuffers *rb)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -     int ret;
> > > > -
> > > > -     ret = uvc_acquire_privileges(handle);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > -
> > > > -     mutex_lock(&stream->mutex);
> > > > -     ret = uvc_request_buffers(&stream->queue, rb);
> > > > -     mutex_unlock(&stream->mutex);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > -
> > > > -     if (ret == 0)
> > > > -             uvc_dismiss_privileges(handle);
> > > > -
> > > > -     return 0;
> > > > -}
> > > > -
> > > > -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> > > > -                           struct v4l2_buffer *buf)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     return uvc_query_buffer(&stream->queue, buf);
> > > > -}
> > > > -
> > > > -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     return uvc_queue_buffer(&stream->queue,
> > > > -                             stream->vdev.v4l2_dev->mdev, buf);
> > > > -}
> > > > -
> > > > -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> > > > -                         struct v4l2_exportbuffer *exp)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     return uvc_export_buffer(&stream->queue, exp);
> > > > -}
> > > > -
> > > > -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     return uvc_dequeue_buffer(&stream->queue, buf,
> > > > -                               file->f_flags & O_NONBLOCK);
> > > > -}
> > > > -
> > > > -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> > > > -                               struct v4l2_create_buffers *cb)
> > > > -{
> > > > -     struct uvc_fh *handle = fh;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -     int ret;
> > > > -
> > > > -     ret = uvc_acquire_privileges(handle);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > -
> > > > -     return uvc_create_buffers(&stream->queue, cb);
> > > > -}
> > > > -
> > > >  static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > >                             enum v4l2_buf_type type)
> > > >  {
> > > > @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > >       struct uvc_streaming *stream = handle->stream;
> > > >       int ret;
> > > >
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     guard(mutex)(&stream->mutex);
> > > > -
> > > >       if (handle->is_streaming)
> > > >               return 0;
> > > >
> > > > @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > >       if (ret)
> > > >               return ret;
> > > >
> > > > -     ret = uvc_queue_streamon(&stream->queue, type);
> > > > +     ret = vb2_ioctl_streamon(file, fh, type);
> > > >       if (ret) {
> > > >               uvc_pm_put(stream->dev);
> > > >               return ret;
> > > > @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> > > >  {
> > > >       struct uvc_fh *handle = fh;
> > > >       struct uvc_streaming *stream = handle->stream;
> > > > +     int ret;
> > > >
> > > > -     if (!uvc_has_privileges(handle))
> > > > -             return -EBUSY;
> > > > -
> > > > -     guard(mutex)(&stream->mutex);
> > > > +     ret = vb2_ioctl_streamoff(file, fh, type);
> > > > +     if (ret)
> > > > +             return ret;
> > > >
> > > > -     uvc_queue_streamoff(&stream->queue, type);
> > > >       if (handle->is_streaming) {
> > > >               handle->is_streaming = false;
> > > >               uvc_pm_put(stream->dev);
> > > > @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> > > >  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> > > >  {
> > > >       struct uvc_fh *handle = fh;
> > > > +     struct uvc_streaming *stream = handle->stream;
> > > >       struct uvc_video_chain *chain = handle->chain;
> > > >       u8 *buf;
> > > >       int ret;
> > > >
> > > > -     ret = uvc_acquire_privileges(handle);
> > > > -     if (ret < 0)
> > > > -             return ret;
> > > > +     if (vb2_is_busy(&stream->queue.queue))
> > > > +             return -EBUSY;
> > > >
> > > >       if (chain->selector == NULL ||
> > > >           (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> > > > @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> > > >       return ret;
> > > >  }
> > > >
> > > > -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> > > > -                 size_t count, loff_t *ppos)
> > > > -{
> > > > -     struct uvc_fh *handle = file->private_data;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> > > > -     return -EINVAL;
> > > > -}
> > > > -
> > > > -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> > > > -{
> > > > -     struct uvc_fh *handle = file->private_data;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > -
> > > > -     return uvc_queue_mmap(&stream->queue, vma);
> > > > -}
> > > > -
> > > > -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> > > > -{
> > > > -     struct uvc_fh *handle = file->private_data;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > -
> > > > -     return uvc_queue_poll(&stream->queue, file, wait);
> > > > -}
> > > > -
> > > > -#ifndef CONFIG_MMU
> > > > -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> > > > -             unsigned long addr, unsigned long len, unsigned long pgoff,
> > > > -             unsigned long flags)
> > > > -{
> > > > -     struct uvc_fh *handle = file->private_data;
> > > > -     struct uvc_streaming *stream = handle->stream;
> > > > -
> > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > -
> > > > -     return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> > > > -}
> > > > -#endif
> > > > -
> > > >  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > > >       .vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> > > >       .vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> > > > @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > > >       .vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> > > >       .vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> > > >       .vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> > > > -     .vidioc_reqbufs = uvc_ioctl_reqbufs,
> > > > -     .vidioc_querybuf = uvc_ioctl_querybuf,
> > > > -     .vidioc_qbuf = uvc_ioctl_qbuf,
> > > > -     .vidioc_expbuf = uvc_ioctl_expbuf,
> > > > -     .vidioc_dqbuf = uvc_ioctl_dqbuf,
> > > > -     .vidioc_create_bufs = uvc_ioctl_create_bufs,
> > > > +     .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > > > +     .vidioc_querybuf = vb2_ioctl_querybuf,
> > > > +     .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> > > > +     .vidioc_qbuf = vb2_ioctl_qbuf,
> > > > +     .vidioc_expbuf = vb2_ioctl_expbuf,
> > > > +     .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > > > +     .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > > >       .vidioc_streamon = uvc_ioctl_streamon,
> > > >       .vidioc_streamoff = uvc_ioctl_streamoff,
> > > >       .vidioc_enum_input = uvc_ioctl_enum_input,
> > > > @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> > > >  #ifdef CONFIG_COMPAT
> > > >       .compat_ioctl32 = uvc_v4l2_compat_ioctl32,
> > > >  #endif
> > > > -     .read           = uvc_v4l2_read,
> > > > -     .mmap           = uvc_v4l2_mmap,
> > > > -     .poll           = uvc_v4l2_poll,
> > > > +     .mmap           = vb2_fop_mmap,
> > > > +     .poll           = vb2_fop_poll,
> > > >  #ifndef CONFIG_MMU
> > > > -     .get_unmapped_area = uvc_v4l2_get_unmapped_area,
> > > > +     .get_unmapped_area = vb2_fop_get_unmapped_area,
> > > >  #endif
> > > >  };
> > > >
> > > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > > index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> > > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > > @@ -326,7 +326,10 @@ struct uvc_buffer {
> > > >
> > > >  struct uvc_video_queue {
> > > >       struct vb2_queue queue;
> > > > -     struct mutex mutex;                     /* Protects queue */
> > > > +     struct mutex mutex;                     /*
> > > > +                                              * Serializes vb2_queue and
> > > > +                                              * fops
> > > > +                                              */
> > > >
> > > >       unsigned int flags;
> > > >       unsigned int buf_used;
> > > > @@ -349,7 +352,6 @@ struct uvc_video_chain {
> > > >                                                * uvc_fh.pending_async_ctrls
> > > >                                                */
> > > >
> > > > -     struct v4l2_prio_state prio;            /* V4L2 priority state */
> > > >       u32 caps;                               /* V4L2 chain-wide caps */
> > > >       u8 ctrl_class_bitmap;                   /* Bitmap of valid classes */
> > > >  };
> > > > @@ -619,16 +621,10 @@ struct uvc_device {
> > > >       struct uvc_entity *gpio_unit;
> > > >  };
> > > >
> > > > -enum uvc_handle_state {
> > > > -     UVC_HANDLE_PASSIVE      = 0,
> > > > -     UVC_HANDLE_ACTIVE       = 1,
> > > > -};
> > > > -
> > > >  struct uvc_fh {
> > > >       struct v4l2_fh vfh;
> > > >       struct uvc_video_chain *chain;
> > > >       struct uvc_streaming *stream;
> > > > -     enum uvc_handle_state state;
> > > >       unsigned int pending_async_ctrls;
> > > >       bool is_streaming;
> > > >  };
> > > > @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> > > >
> > > >  /* Video buffers queue management. */
> > > >  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > > -void uvc_queue_release(struct uvc_video_queue *queue);
> > > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > > -                     struct v4l2_requestbuffers *rb);
> > > > -int uvc_query_buffer(struct uvc_video_queue *queue,
> > > > -                  struct v4l2_buffer *v4l2_buf);
> > > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > > -                    struct v4l2_create_buffers *v4l2_cb);
> > > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > > -                  struct media_device *mdev,
> > > > -                  struct v4l2_buffer *v4l2_buf);
> > > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > > -                   struct v4l2_exportbuffer *exp);
> > > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> > > > -                    struct v4l2_buffer *v4l2_buf, int nonblocking);
> > > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > >  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> > > >  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> > > >                                        struct uvc_buffer *buf);
> > > >  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> > > >  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> > > > -int uvc_queue_mmap(struct uvc_video_queue *queue,
> > > > -                struct vm_area_struct *vma);
> > > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > > -                     poll_table *wait);
> > > > -#ifndef CONFIG_MMU
> > > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > > -                                       unsigned long pgoff);
> > > > -#endif
> > > > -int uvc_queue_allocated(struct uvc_video_queue *queue);
> > > >  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> > > >  {
> > > >       return vb2_is_streaming(&queue->queue);
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda

Re: [PATCH v2 2/3] media: uvcvideo: Use vb2 ioctl and fop helpers

[Laurent Pinchart]

Hi Ricardo,

On Tue, Jun 03, 2025 at 12:07:09PM +0200, Ricardo Ribalda wrote:
> On Tue, 3 Jun 2025 at 10:49, Laurent Pinchart wrote:
> > On Mon, Jun 02, 2025 at 09:53:09PM +0200, Ricardo Ribalda wrote:
> > > On Mon, 2 Jun 2025 at 20:31, Laurent Pinchart wrote:
> > > > On Mon, Jun 02, 2025 at 12:59:03PM +0000, Ricardo Ribalda wrote:
> > > > > From: Hans Verkuil <hans@jjverkuil.nl>
> > > > >
> > > > > When uvc was written the vb2 ioctl and file operation helpers didn't exist.
> > > > >
> > > > > This patch switches uvc over to those helpers, which removes a lot of
> > > > > boilerplate code and simplifies VIDIOC_G/S_PRIORITY handling
> > > >
> > > > How does it simplify VIDIOC_[GS]_PRIORITY handling ? The only thing this
> > > > patch does related to priority is replace the per-chain priority
> > > > handling with a per-device (as in uvc_device) priority, as the default
> > > > is to use the prio state from v4l2_device. I think this is actually
> > > > incorrect, a UVC device can have multiple independent streaming
> > > > interfaces, so the priority ioctls should no operate on a device-wide
> > > > prio state. Am I missing something ?
> > >
> > > You are correct.
> > > The uvcvideo is the only driver that does not use the prio state from
> > > v4l2_device and it makes v4l2-core a bit more complicated.
> > >
> > > I have not seen a real use of  VIDIOC_[GS]_PRIORITY, so being a bit
> > > incorrect in favor of simplicity is probably a good trade-off.
> > > Anyway it is an easy change to split into a different patch, we can
> > > have the discussion about prio there.
> > >
> > > > > and allows us
> > > > > to drop the 'privileges' scheme, since that's now handled inside the vb2
> > > > > helpers.
> > > >
> > > > That part is correct. The driver implements a privilege-management
> > > > system similar to the vb2_queue_is_busy() checks in the vb2 ioctl
> > > > handlers, as the ioctl handlers didn't exist back then.
> > > >
> > > > Please reword the commit message to make this clearer. If the prio
> > > > change is also desired, it should be split in a separate patch.
> > > >
> > > > > This makes it possible for uvc to fix the v4l2-compliance streaming tests:
> > > > >  warn: v4l2-test-formats.cpp(1075): Could not set fmt2
> > > > >
> > > > > This patch introduces a change on behavior on the uvcdriver to be
> > > > > aligned with the rest of the subsystem. Now S_INPUT, S_PARM and
> > > > > S_FORMAT do no grant exclusive ownership of the device.
> > > >
> > > > There are other changes in behaviour worth noting, some small, some
> > > > quite substantial. Let's start with the small one: .vidioc_querybuf()
> > > > now succeeds when the queue is busy. It seems a check may be missing in
> > > > v4l2-compliance for this.
> > >
> > > Agree,
> > > After we land this we can add the check to v4l2-compliance.
> > >
> > > > The bigger change is related to locking. See below.
> > > >
> > > > > Reviewed-by: Hans de Goede <hansg@kernel.org>
> > > > > Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
> > > > > Signed-off-by: Hans Verkuil <hans@jjverkuil.nl>
> > > > > Co-developed-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > > > > ---
> > > > >  drivers/media/usb/uvc/uvc_driver.c   |  34 +----
> > > > >  drivers/media/usb/uvc/uvc_metadata.c |   8 +-
> > > > >  drivers/media/usb/uvc/uvc_queue.c    | 143 --------------------
> > > > >  drivers/media/usb/uvc/uvc_v4l2.c     | 251 +++--------------------------------
> > > > >  drivers/media/usb/uvc/uvcvideo.h     |  37 +-----
> > > > >  5 files changed, 30 insertions(+), 443 deletions(-)
> > > > >
> > > > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > > > > index da24a655ab68cc0957762f2b67387677c22224d1..4eeedab93b90939fc4c925012a18b7d018ade39f 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_driver.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > > > > @@ -1725,7 +1725,6 @@ static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev)
> > > > >       INIT_LIST_HEAD(&chain->entities);
> > > > >       mutex_init(&chain->ctrl_mutex);
> > > > >       chain->dev = dev;
> > > > > -     v4l2_prio_init(&chain->prio);
> > > > >
> > > > >       return chain;
> > > > >  }
> > > > > @@ -1958,31 +1957,7 @@ static void uvc_unregister_video(struct uvc_device *dev)
> > > > >               if (!video_is_registered(&stream->vdev))
> > > > >                       continue;
> > > > >
> > > > > -             /*
> > > > > -              * For stream->vdev we follow the same logic as:
> > > > > -              * vb2_video_unregister_device().
> > > > > -              */
> > > > > -
> > > > > -             /* 1. Take a reference to vdev */
> > > > > -             get_device(&stream->vdev.dev);
> > > > > -
> > > > > -             /* 2. Ensure that no new ioctls can be called. */
> > > > > -             video_unregister_device(&stream->vdev);
> > > > > -
> > > > > -             /* 3. Wait for old ioctls to finish. */
> > > > > -             mutex_lock(&stream->mutex);
> > > > > -
> > > > > -             /* 4. Stop streaming. */
> > > > > -             uvc_queue_release(&stream->queue);
> > > > > -
> > > > > -             mutex_unlock(&stream->mutex);
> > > > > -
> > > > > -             put_device(&stream->vdev.dev);
> > > > > -
> > > > > -             /*
> > > > > -              * For stream->meta.vdev we can directly call:
> > > > > -              * vb2_video_unregister_device().
> > > > > -              */
> > > > > +             vb2_video_unregister_device(&stream->vdev);
> > > > >               vb2_video_unregister_device(&stream->meta.vdev);
> > > > >
> > > > >               /*
> > > > > @@ -2029,7 +2004,8 @@ int uvc_register_video_device(struct uvc_device *dev,
> > > > >       vdev->fops = fops;
> > > > >       vdev->ioctl_ops = ioctl_ops;
> > > > >       vdev->release = uvc_release;
> > > > > -     vdev->prio = &stream->chain->prio;
> > > > > +     vdev->queue = &queue->queue;
> > > > > +     vdev->lock = &queue->mutex;
> > > >
> > > > This will cause the ioctl handlers to use queue->mutex for all ioctls
> > > > (both INFO_FL_QUEUE and !INFO_FL_QUEUE). Locking therefore gets more
> > > > coarse, that should be mentioned in the commit message.
> > > >
> > > > >       if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
> > > > >               vdev->vfl_dir = VFL_DIR_TX;
> > > > >       else
> > > > > @@ -2399,8 +2375,8 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
> > > > >               if (stream->intf == intf) {
> > > > >                       ret = uvc_video_resume(stream, reset);
> > > > >                       if (ret < 0)
> > > > > -                             uvc_queue_streamoff(&stream->queue,
> > > > > -                                                 stream->queue.queue.type);
> > > > > +                             vb2_streamoff(&stream->queue.queue,
> > > > > +                                           stream->queue.queue.type);
> > > >
> > > > This doesn't take any lock anymore. Can that be a problem ?
> > >
> > > ack
> > > Probably better to keep the same lock pattern as before. I am adding
> > > mutex_lock/unlock
> > >
> > > > >                       return ret;
> > > > >               }
> > > > >       }
> > > > > diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
> > > > > index 82de7781f5b6b70c5ba16bcba9e0741231231904..d3aab22f91cea21aefc56409924dfa1451aec914 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_metadata.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_metadata.c
> > > > > @@ -96,7 +96,7 @@ static int uvc_meta_v4l2_set_format(struct file *file, void *fh,
> > > > >        */
> > > > >       mutex_lock(&stream->mutex);
> > > >
> > > > Is this lock still needed ? More broadly speaking, what's the remaining
> > > > purpose of stream->mutex ? Or perhaps the other way around, shouldn't we
> > > > drop queue->mutex, and use stream->mutex everywhere instead ?
> > >
> > > Good question, this is the first thing that I tried, and there are
> > > plenty of nested locking that are wrong:
> > > lock(stream->mutex)
> > >   lock(stream->muex)
> > >
> > > It is probably fixable, but we can do that as a follow-up patch.
> >
> > The current locking scheme was designed with two locks, to separate
> > locking of the buffer-related ioctls from the other ioctls, the same way
> > that the V4L2 core has a video_device lock and a vb2_queue lock. We
> > could keep the same design and move to using separate video_device and
> > vb2_queue locks, but that's not what this patch does. I'm OK with
> > switching to a single lock as I can't provide compelling evidence that
> > two locks significantly improve performance (do they ever, or should
> > V4L2 drop that ?) with uvcvideo at the moment, but I'd like the locking
> > scheme to remain clean and understandable.
> 
> I agree with your goal of having a single lock. The question is how to
> reach that goal.
> 
> I think it is easier/better to do it in two steps:
> 1) Land this set, where the queue->mutex locks more ioctls than
> before, and we keep the stream->mutex
> 2) Remove one of the mutex.
> 
> My reasons are:
> - You, HdG, HansV  and I are familiar with the current change and have
> already reviewed it.
> - Completely refactoring the locking in the same patch will make the
> code more difficult to review.
> - There are other patchsets that conflict with this set.
> - HansV expressed that he wants this addressed with priority.
> - The patch fixes v4l2-compliance.
> - The patch simplifies the code.
> 
> I will look into the new locking the same way that I have been looking
> into other housekeeping changes in the uvc driver. But I do not
> believe that we should block the development for this.

I disagree this is best done on top, but I won't block the series for
this. I do however expect a new patch series to address the issue, I
feel quite uncomfortable leaving the code in its current state as it
gives me an impression of an unfinished job that leaves possible bugs
behind.

> > > > >
> > > > > -     if (uvc_queue_allocated(&stream->queue))
> > > > > +     if (vb2_is_busy(&stream->meta.queue.queue))
> > > > >               ret = -EBUSY;
> > > > >       else
> > > > >               stream->meta.format = fmt->dataformat;
> > > > > @@ -164,12 +164,6 @@ int uvc_meta_register(struct uvc_streaming *stream)
> > > > >
> > > > >       stream->meta.format = V4L2_META_FMT_UVC;
> > > > >
> > > > > -     /*
> > > > > -      * The video interface queue uses manual locking and thus does not set
> > > > > -      * the queue pointer. Set it manually here.
> > > > > -      */
> > > > > -     vdev->queue = &queue->queue;
> > > > > -
> > > > >       return uvc_register_video_device(dev, stream, vdev, queue,
> > > > >                                        V4L2_BUF_TYPE_META_CAPTURE,
> > > > >                                        &uvc_meta_fops, &uvc_meta_ioctl_ops);
> > > > > diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
> > > > > index 2ee142621042167c2587b6a6fdd51c1a46d31c11..72c5494dee9f46ff61072e7d293bfaddda40e615 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_queue.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_queue.c
> > > > > @@ -242,153 +242,10 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > > >       return 0;
> > > > >  }
> > > > >
> > > > > -void uvc_queue_release(struct uvc_video_queue *queue)
> > > > > -{
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     vb2_queue_release(&queue->queue);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -}
> > > > > -
> > > > > -/* -----------------------------------------------------------------------------
> > > > > - * V4L2 queue operations
> > > > > - */
> > > > > -
> > > > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > > > -                     struct v4l2_requestbuffers *rb)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_reqbufs(&queue->queue, rb);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret ? ret : rb->count;
> > > > > -}
> > > > > -
> > > > > -int uvc_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_querybuf(&queue->queue, buf);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > > > -                    struct v4l2_create_buffers *cb)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_create_bufs(&queue->queue, cb);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > > > -                  struct media_device *mdev, struct v4l2_buffer *buf)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_qbuf(&queue->queue, mdev, buf);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > > > -                   struct v4l2_exportbuffer *exp)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_expbuf(&queue->queue, exp);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
> > > > > -                    int nonblocking)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_dqbuf(&queue->queue, buf, nonblocking);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_streamon(&queue->queue, type);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type)
> > > > > -{
> > > > > -     int ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_streamoff(&queue->queue, type);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > > -int uvc_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
> > > > > -{
> > > > > -     return vb2_mmap(&queue->queue, vma);
> > > > > -}
> > > > > -
> > > > > -#ifndef CONFIG_MMU
> > > > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > > > -             unsigned long pgoff)
> > > > > -{
> > > > > -     return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
> > > > > -}
> > > > > -#endif
> > > > > -
> > > > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > > > -                         poll_table *wait)
> > > > > -{
> > > > > -     __poll_t ret;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     ret = vb2_poll(&queue->queue, file, wait);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return ret;
> > > > > -}
> > > > > -
> > > > >  /* -----------------------------------------------------------------------------
> > > > >   *
> > > > >   */
> > > > >
> > > > > -/*
> > > > > - * Check if buffers have been allocated.
> > > > > - */
> > > > > -int uvc_queue_allocated(struct uvc_video_queue *queue)
> > > > > -{
> > > > > -     int allocated;
> > > > > -
> > > > > -     mutex_lock(&queue->mutex);
> > > > > -     allocated = vb2_is_busy(&queue->queue);
> > > > > -     mutex_unlock(&queue->mutex);
> > > > > -
> > > > > -     return allocated;
> > > > > -}
> > > > > -
> > > > >  /*
> > > > >   * Cancel the video buffers queue.
> > > > >   *
> > > > > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > > > > index 862b4e34e5b629cf324479a9bb59ebe8784ccd5d..7a5ecbefa32c0a6b74c85d7f77a25b433598471e 100644
> > > > > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > > > > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > > > > @@ -47,8 +47,6 @@ void uvc_pm_put(struct uvc_device *dev)
> > > > >       usb_autopm_put_interface(dev->intf);
> > > > >  }
> > > > >
> > > > > -static int uvc_acquire_privileges(struct uvc_fh *handle);
> > > > > -
> > > > >  static int uvc_control_add_xu_mapping(struct uvc_video_chain *chain,
> > > > >                                     struct uvc_control_mapping *map,
> > > > >                                     const struct uvc_xu_control_mapping *xmap)
> > > > > @@ -436,10 +434,6 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > > > >       const struct uvc_frame *frame;
> > > > >       int ret;
> > > > >
> > > > > -     ret = uvc_acquire_privileges(handle);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > -
> > > > >       if (fmt->type != stream->type)
> > > > >               return -EINVAL;
> > > > >
> > > > > @@ -448,8 +442,7 @@ static int uvc_ioctl_s_fmt(struct file *file, void *fh,
> > > > >               return ret;
> > > > >
> > > > >       mutex_lock(&stream->mutex);
> > > > > -
> > > > > -     if (uvc_queue_allocated(&stream->queue)) {
> > > > > +     if (vb2_is_busy(&stream->queue.queue)) {
> > > > >               ret = -EBUSY;
> > > > >               goto done;
> > > > >       }
> > > > > @@ -513,10 +506,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > > > >       unsigned int i;
> > > > >       int ret;
> > > > >
> > > > > -     ret = uvc_acquire_privileges(handle);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > -
> > > > >       if (parm->type != stream->type)
> > > > >               return -EINVAL;
> > > > >
> > > > > @@ -593,63 +582,6 @@ static int uvc_ioctl_s_parm(struct file *file, void *fh,
> > > > >       return 0;
> > > > >  }
> > > > >
> > > > > -/* ------------------------------------------------------------------------
> > > > > - * Privilege management
> > > > > - */
> > > > > -
> > > > > -/*
> > > > > - * Privilege management is the multiple-open implementation basis. The current
> > > > > - * implementation is completely transparent for the end-user and doesn't
> > > > > - * require explicit use of the VIDIOC_G_PRIORITY and VIDIOC_S_PRIORITY ioctls.
> > > > > - * Those ioctls enable finer control on the device (by making possible for a
> > > > > - * user to request exclusive access to a device), but are not mature yet.
> > > > > - * Switching to the V4L2 priority mechanism might be considered in the future
> > > > > - * if this situation changes.
> > > > > - *
> > > > > - * Each open instance of a UVC device can either be in a privileged or
> > > > > - * unprivileged state. Only a single instance can be in a privileged state at
> > > > > - * a given time. Trying to perform an operation that requires privileges will
> > > > > - * automatically acquire the required privileges if possible, or return -EBUSY
> > > > > - * otherwise. Privileges are dismissed when closing the instance or when
> > > > > - * freeing the video buffers using VIDIOC_REQBUFS.
> > > > > - *
> > > > > - * Operations that require privileges are:
> > > > > - *
> > > > > - * - VIDIOC_S_INPUT
> > > > > - * - VIDIOC_S_PARM
> > > > > - * - VIDIOC_S_FMT
> > > > > - * - VIDIOC_CREATE_BUFS
> > > > > - * - VIDIOC_REQBUFS
> > > > > - */
> > > > > -static int uvc_acquire_privileges(struct uvc_fh *handle)
> > > > > -{
> > > > > -     /* Always succeed if the handle is already privileged. */
> > > > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > > > -             return 0;
> > > > > -
> > > > > -     /* Check if the device already has a privileged handle. */
> > > > > -     if (atomic_inc_return(&handle->stream->active) != 1) {
> > > > > -             atomic_dec(&handle->stream->active);
> > > > > -             return -EBUSY;
> > > > > -     }
> > > > > -
> > > > > -     handle->state = UVC_HANDLE_ACTIVE;
> > > > > -     return 0;
> > > > > -}
> > > > > -
> > > > > -static void uvc_dismiss_privileges(struct uvc_fh *handle)
> > > > > -{
> > > > > -     if (handle->state == UVC_HANDLE_ACTIVE)
> > > > > -             atomic_dec(&handle->stream->active);
> > > > > -
> > > > > -     handle->state = UVC_HANDLE_PASSIVE;
> > > > > -}
> > > > > -
> > > > > -static int uvc_has_privileges(struct uvc_fh *handle)
> > > > > -{
> > > > > -     return handle->state == UVC_HANDLE_ACTIVE;
> > > > > -}
> > > > > -
> > > > >  /* ------------------------------------------------------------------------
> > > > >   * V4L2 file operations
> > > > >   */
> > > > > @@ -671,7 +603,6 @@ static int uvc_v4l2_open(struct file *file)
> > > > >       v4l2_fh_add(&handle->vfh);
> > > > >       handle->chain = stream->chain;
> > > > >       handle->stream = stream;
> > > > > -     handle->state = UVC_HANDLE_PASSIVE;
> > > > >       file->private_data = handle;
> > > > >
> > > > >       return 0;
> > > > > @@ -686,18 +617,11 @@ static int uvc_v4l2_release(struct file *file)
> > > > >
> > > > >       uvc_ctrl_cleanup_fh(handle);
> > > > >
> > > > > -     /* Only free resources if this is a privileged handle. */
> > > > > -     if (uvc_has_privileges(handle))
> > > > > -             uvc_queue_release(&stream->queue);
> > > > > -
> > > > >       if (handle->is_streaming)
> > > > >               uvc_pm_put(stream->dev);
> > > > >
> > > > >       /* Release the file handle. */
> > > > > -     uvc_dismiss_privileges(handle);
> > > > > -     v4l2_fh_del(&handle->vfh);
> > > > > -     v4l2_fh_exit(&handle->vfh);
> > > > > -     kfree(handle);
> > > > > +     vb2_fop_release(file);
> > > > >       file->private_data = NULL;
> > > >
> > > > You can drop setting private_data to NULL, it's done by
> > > > v4l2_fh_release() called by vb2_fop_release().
> > >
> > > ack
> > >
> > > > >
> > > > >       return 0;
> > > > > @@ -753,91 +677,6 @@ static int uvc_ioctl_try_fmt(struct file *file, void *fh,
> > > > >       return uvc_v4l2_try_format(stream, fmt, &probe, NULL, NULL);
> > > > >  }
> > > > >
> > > > > -static int uvc_ioctl_reqbufs(struct file *file, void *fh,
> > > > > -                          struct v4l2_requestbuffers *rb)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -     int ret;
> > > > > -
> > > > > -     ret = uvc_acquire_privileges(handle);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > -
> > > > > -     mutex_lock(&stream->mutex);
> > > > > -     ret = uvc_request_buffers(&stream->queue, rb);
> > > > > -     mutex_unlock(&stream->mutex);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > -
> > > > > -     if (ret == 0)
> > > > > -             uvc_dismiss_privileges(handle);
> > > > > -
> > > > > -     return 0;
> > > > > -}
> > > > > -
> > > > > -static int uvc_ioctl_querybuf(struct file *file, void *fh,
> > > > > -                           struct v4l2_buffer *buf)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     return uvc_query_buffer(&stream->queue, buf);
> > > > > -}
> > > > > -
> > > > > -static int uvc_ioctl_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     return uvc_queue_buffer(&stream->queue,
> > > > > -                             stream->vdev.v4l2_dev->mdev, buf);
> > > > > -}
> > > > > -
> > > > > -static int uvc_ioctl_expbuf(struct file *file, void *fh,
> > > > > -                         struct v4l2_exportbuffer *exp)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     return uvc_export_buffer(&stream->queue, exp);
> > > > > -}
> > > > > -
> > > > > -static int uvc_ioctl_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     return uvc_dequeue_buffer(&stream->queue, buf,
> > > > > -                               file->f_flags & O_NONBLOCK);
> > > > > -}
> > > > > -
> > > > > -static int uvc_ioctl_create_bufs(struct file *file, void *fh,
> > > > > -                               struct v4l2_create_buffers *cb)
> > > > > -{
> > > > > -     struct uvc_fh *handle = fh;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -     int ret;
> > > > > -
> > > > > -     ret = uvc_acquire_privileges(handle);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > -
> > > > > -     return uvc_create_buffers(&stream->queue, cb);
> > > > > -}
> > > > > -
> > > > >  static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > > >                             enum v4l2_buf_type type)
> > > > >  {
> > > > > @@ -845,11 +684,6 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > > >       struct uvc_streaming *stream = handle->stream;
> > > > >       int ret;
> > > > >
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     guard(mutex)(&stream->mutex);
> > > > > -
> > > > >       if (handle->is_streaming)
> > > > >               return 0;
> > > > >
> > > > > @@ -857,7 +691,7 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
> > > > >       if (ret)
> > > > >               return ret;
> > > > >
> > > > > -     ret = uvc_queue_streamon(&stream->queue, type);
> > > > > +     ret = vb2_ioctl_streamon(file, fh, type);
> > > > >       if (ret) {
> > > > >               uvc_pm_put(stream->dev);
> > > > >               return ret;
> > > > > @@ -873,13 +707,12 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
> > > > >  {
> > > > >       struct uvc_fh *handle = fh;
> > > > >       struct uvc_streaming *stream = handle->stream;
> > > > > +     int ret;
> > > > >
> > > > > -     if (!uvc_has_privileges(handle))
> > > > > -             return -EBUSY;
> > > > > -
> > > > > -     guard(mutex)(&stream->mutex);
> > > > > +     ret = vb2_ioctl_streamoff(file, fh, type);
> > > > > +     if (ret)
> > > > > +             return ret;
> > > > >
> > > > > -     uvc_queue_streamoff(&stream->queue, type);
> > > > >       if (handle->is_streaming) {
> > > > >               handle->is_streaming = false;
> > > > >               uvc_pm_put(stream->dev);
> > > > > @@ -962,13 +795,13 @@ static int uvc_ioctl_g_input(struct file *file, void *fh, unsigned int *input)
> > > > >  static int uvc_ioctl_s_input(struct file *file, void *fh, unsigned int input)
> > > > >  {
> > > > >       struct uvc_fh *handle = fh;
> > > > > +     struct uvc_streaming *stream = handle->stream;
> > > > >       struct uvc_video_chain *chain = handle->chain;
> > > > >       u8 *buf;
> > > > >       int ret;
> > > > >
> > > > > -     ret = uvc_acquire_privileges(handle);
> > > > > -     if (ret < 0)
> > > > > -             return ret;
> > > > > +     if (vb2_is_busy(&stream->queue.queue))
> > > > > +             return -EBUSY;
> > > > >
> > > > >       if (chain->selector == NULL ||
> > > > >           (chain->dev->quirks & UVC_QUIRK_IGNORE_SELECTOR_UNIT)) {
> > > > > @@ -1471,50 +1304,6 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
> > > > >       return ret;
> > > > >  }
> > > > >
> > > > > -static ssize_t uvc_v4l2_read(struct file *file, char __user *data,
> > > > > -                 size_t count, loff_t *ppos)
> > > > > -{
> > > > > -     struct uvc_fh *handle = file->private_data;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     uvc_dbg(stream->dev, CALLS, "%s: not implemented\n", __func__);
> > > > > -     return -EINVAL;
> > > > > -}
> > > > > -
> > > > > -static int uvc_v4l2_mmap(struct file *file, struct vm_area_struct *vma)
> > > > > -{
> > > > > -     struct uvc_fh *handle = file->private_data;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > > -
> > > > > -     return uvc_queue_mmap(&stream->queue, vma);
> > > > > -}
> > > > > -
> > > > > -static __poll_t uvc_v4l2_poll(struct file *file, poll_table *wait)
> > > > > -{
> > > > > -     struct uvc_fh *handle = file->private_data;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > > -
> > > > > -     return uvc_queue_poll(&stream->queue, file, wait);
> > > > > -}
> > > > > -
> > > > > -#ifndef CONFIG_MMU
> > > > > -static unsigned long uvc_v4l2_get_unmapped_area(struct file *file,
> > > > > -             unsigned long addr, unsigned long len, unsigned long pgoff,
> > > > > -             unsigned long flags)
> > > > > -{
> > > > > -     struct uvc_fh *handle = file->private_data;
> > > > > -     struct uvc_streaming *stream = handle->stream;
> > > > > -
> > > > > -     uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> > > > > -
> > > > > -     return uvc_queue_get_unmapped_area(&stream->queue, pgoff);
> > > > > -}
> > > > > -#endif
> > > > > -
> > > > >  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > > > >       .vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> > > > >       .vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
> > > > > @@ -1527,12 +1316,13 @@ const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> > > > >       .vidioc_enum_fmt_vid_out = uvc_ioctl_enum_fmt,
> > > > >       .vidioc_try_fmt_vid_cap = uvc_ioctl_try_fmt,
> > > > >       .vidioc_try_fmt_vid_out = uvc_ioctl_try_fmt,
> > > > > -     .vidioc_reqbufs = uvc_ioctl_reqbufs,
> > > > > -     .vidioc_querybuf = uvc_ioctl_querybuf,
> > > > > -     .vidioc_qbuf = uvc_ioctl_qbuf,
> > > > > -     .vidioc_expbuf = uvc_ioctl_expbuf,
> > > > > -     .vidioc_dqbuf = uvc_ioctl_dqbuf,
> > > > > -     .vidioc_create_bufs = uvc_ioctl_create_bufs,
> > > > > +     .vidioc_reqbufs = vb2_ioctl_reqbufs,
> > > > > +     .vidioc_querybuf = vb2_ioctl_querybuf,
> > > > > +     .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> > > > > +     .vidioc_qbuf = vb2_ioctl_qbuf,
> > > > > +     .vidioc_expbuf = vb2_ioctl_expbuf,
> > > > > +     .vidioc_dqbuf = vb2_ioctl_dqbuf,
> > > > > +     .vidioc_create_bufs = vb2_ioctl_create_bufs,
> > > > >       .vidioc_streamon = uvc_ioctl_streamon,
> > > > >       .vidioc_streamoff = uvc_ioctl_streamoff,
> > > > >       .vidioc_enum_input = uvc_ioctl_enum_input,
> > > > > @@ -1559,11 +1349,10 @@ const struct v4l2_file_operations uvc_fops = {
> > > > >  #ifdef CONFIG_COMPAT
> > > > >       .compat_ioctl32 = uvc_v4l2_compat_ioctl32,
> > > > >  #endif
> > > > > -     .read           = uvc_v4l2_read,
> > > > > -     .mmap           = uvc_v4l2_mmap,
> > > > > -     .poll           = uvc_v4l2_poll,
> > > > > +     .mmap           = vb2_fop_mmap,
> > > > > +     .poll           = vb2_fop_poll,
> > > > >  #ifndef CONFIG_MMU
> > > > > -     .get_unmapped_area = uvc_v4l2_get_unmapped_area,
> > > > > +     .get_unmapped_area = vb2_fop_get_unmapped_area,
> > > > >  #endif
> > > > >  };
> > > > >
> > > > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > > > > index b9f8eb62ba1d82ea7788cf6c10cc838a429dbc9e..3ddbf065a2cbae40ee48cb06f84ca8f0052990c4 100644
> > > > > --- a/drivers/media/usb/uvc/uvcvideo.h
> > > > > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > > > > @@ -326,7 +326,10 @@ struct uvc_buffer {
> > > > >
> > > > >  struct uvc_video_queue {
> > > > >       struct vb2_queue queue;
> > > > > -     struct mutex mutex;                     /* Protects queue */
> > > > > +     struct mutex mutex;                     /*
> > > > > +                                              * Serializes vb2_queue and
> > > > > +                                              * fops
> > > > > +                                              */
> > > > >
> > > > >       unsigned int flags;
> > > > >       unsigned int buf_used;
> > > > > @@ -349,7 +352,6 @@ struct uvc_video_chain {
> > > > >                                                * uvc_fh.pending_async_ctrls
> > > > >                                                */
> > > > >
> > > > > -     struct v4l2_prio_state prio;            /* V4L2 priority state */
> > > > >       u32 caps;                               /* V4L2 chain-wide caps */
> > > > >       u8 ctrl_class_bitmap;                   /* Bitmap of valid classes */
> > > > >  };
> > > > > @@ -619,16 +621,10 @@ struct uvc_device {
> > > > >       struct uvc_entity *gpio_unit;
> > > > >  };
> > > > >
> > > > > -enum uvc_handle_state {
> > > > > -     UVC_HANDLE_PASSIVE      = 0,
> > > > > -     UVC_HANDLE_ACTIVE       = 1,
> > > > > -};
> > > > > -
> > > > >  struct uvc_fh {
> > > > >       struct v4l2_fh vfh;
> > > > >       struct uvc_video_chain *chain;
> > > > >       struct uvc_streaming *stream;
> > > > > -     enum uvc_handle_state state;
> > > > >       unsigned int pending_async_ctrls;
> > > > >       bool is_streaming;
> > > > >  };
> > > > > @@ -687,36 +683,11 @@ struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id);
> > > > >
> > > > >  /* Video buffers queue management. */
> > > > >  int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > > > -void uvc_queue_release(struct uvc_video_queue *queue);
> > > > > -int uvc_request_buffers(struct uvc_video_queue *queue,
> > > > > -                     struct v4l2_requestbuffers *rb);
> > > > > -int uvc_query_buffer(struct uvc_video_queue *queue,
> > > > > -                  struct v4l2_buffer *v4l2_buf);
> > > > > -int uvc_create_buffers(struct uvc_video_queue *queue,
> > > > > -                    struct v4l2_create_buffers *v4l2_cb);
> > > > > -int uvc_queue_buffer(struct uvc_video_queue *queue,
> > > > > -                  struct media_device *mdev,
> > > > > -                  struct v4l2_buffer *v4l2_buf);
> > > > > -int uvc_export_buffer(struct uvc_video_queue *queue,
> > > > > -                   struct v4l2_exportbuffer *exp);
> > > > > -int uvc_dequeue_buffer(struct uvc_video_queue *queue,
> > > > > -                    struct v4l2_buffer *v4l2_buf, int nonblocking);
> > > > > -int uvc_queue_streamon(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > > > -int uvc_queue_streamoff(struct uvc_video_queue *queue, enum v4l2_buf_type type);
> > > > >  void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
> > > > >  struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
> > > > >                                        struct uvc_buffer *buf);
> > > > >  struct uvc_buffer *uvc_queue_get_current_buffer(struct uvc_video_queue *queue);
> > > > >  void uvc_queue_buffer_release(struct uvc_buffer *buf);
> > > > > -int uvc_queue_mmap(struct uvc_video_queue *queue,
> > > > > -                struct vm_area_struct *vma);
> > > > > -__poll_t uvc_queue_poll(struct uvc_video_queue *queue, struct file *file,
> > > > > -                     poll_table *wait);
> > > > > -#ifndef CONFIG_MMU
> > > > > -unsigned long uvc_queue_get_unmapped_area(struct uvc_video_queue *queue,
> > > > > -                                       unsigned long pgoff);
> > > > > -#endif
> > > > > -int uvc_queue_allocated(struct uvc_video_queue *queue);
> > > > >  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
> > > > >  {
> > > > >       return vb2_is_streaming(&queue->queue);

-- 
Regards,

Laurent Pinchart