[PATCH v3 2/3] media: uvcvideo: Refactor the status irq API

Ricardo Ribalda
2024-03-25T16:31:37Z

There are two different use-cases of uvc_status():
- adding/removing a user when the camera is open/closed
- stopping/starting when the camera is suspended/resumed

Make the API reflect these two use-cases and move all the refcounting
and locking logic to the uvc_status.c file.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
drivers/media/usb/uvc/uvc_driver.c | 13 ++-------
drivers/media/usb/uvc/uvc_status.c | 57 ++++++++++++++++++++++++++++++++++++--
drivers/media/usb/uvc/uvc_v4l2.c | 22 ++++-----------
drivers/media/usb/uvc/uvcvideo.h | 10 ++++---
4 files changed, 68 insertions(+), 34 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 17fc945c8deb6..b579644ac0745 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2116,7 +2116,6 @@ static int uvc_probe(struct usb_interface *intf,
INIT_LIST_HEAD(&dev->streams);
kref_init(&dev->ref);
atomic_set(&dev->nmappings, 0);
- mutex_init(&dev->lock);

dev->udev = usb_get_dev(udev);
dev->intf = usb_get_intf(intf);
@@ -2282,10 +2281,7 @@ static int uvc_suspend(struct usb_interface *intf, pm_message_t message)
/* Controls are cached on the fly so they don't need to be saved. */
if (intf->cur_altsetting->desc.bInterfaceSubClass ==
UVC_SC_VIDEOCONTROL) {
- mutex_lock(&dev->lock);
- if (dev->users)
- uvc_status_stop(dev);
- mutex_unlock(&dev->lock);
+ uvc_status_suspend(dev);
return 0;
}

@@ -2316,12 +2312,7 @@ static int __uvc_resume(struct usb_interface *intf, int reset)
return ret;
}

- mutex_lock(&dev->lock);
- if (dev->users)
- ret = uvc_status_start(dev, GFP_NOIO);
- mutex_unlock(&dev->lock);
-
- return ret;
+ return uvc_status_resume(dev);
}

list_for_each_entry(stream, &dev->streams, list) {
diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c
index a78a88c710e24..ff66482346dde 100644
--- a/drivers/media/usb/uvc/uvc_status.c
+++ b/drivers/media/usb/uvc/uvc_status.c
@@ -262,6 +262,8 @@ int uvc_status_init(struct uvc_device *dev)

uvc_input_init(dev);

+ mutex_init(&dev->status_lock);
+
dev->status = kzalloc(sizeof(*dev->status), GFP_KERNEL);
if (!dev->status)
return -ENOMEM;
@@ -292,7 +294,7 @@ int uvc_status_init(struct uvc_device *dev)

void uvc_status_unregister(struct uvc_device *dev)
{
- usb_kill_urb(dev->int_urb);
+ uvc_status_suspend(dev);
uvc_input_unregister(dev);
}

@@ -302,18 +304,22 @@ void uvc_status_cleanup(struct uvc_device *dev)
kfree(dev->status);
}

-int uvc_status_start(struct uvc_device *dev, gfp_t flags)
+static int _uvc_status_start(struct uvc_device *dev, gfp_t flags)
{
+ lockdep_assert_held(&dev->status_lock);
+
if (dev->int_urb == NULL)
return 0;

return usb_submit_urb(dev->int_urb, flags);
}

-void uvc_status_stop(struct uvc_device *dev)
+static void _uvc_status_stop(struct uvc_device *dev)
{
struct uvc_ctrl_work *w = &dev->async_ctrl;

+ lockdep_assert_held(&dev->status_lock);
+
/*
* Prevent the asynchronous control handler from requeing the URB. The
* barrier is needed so the flush_status change is visible to other
@@ -350,3 +356,48 @@ void uvc_status_stop(struct uvc_device *dev)
*/
smp_store_release(&dev->flush_status, false);
}
+
+int uvc_status_resume(struct uvc_device *dev)
+{
+ int ret = 0;
+
+ mutex_lock(&dev->status_lock);
+ if (dev->status_users)
+ ret = _uvc_status_start(dev, GFP_NOIO);
+ mutex_unlock(&dev->status_lock);
+
+ return ret;
+}
+
+void uvc_status_suspend(struct uvc_device *dev)
+{
+ mutex_lock(&dev->status_lock);
+ if (dev->status_users)
+ _uvc_status_stop(dev);
+ mutex_unlock(&dev->status_lock);
+}
+
+int uvc_status_get(struct uvc_device *dev)
+{
+ int ret = 0;
+
+ mutex_lock(&dev->status_lock);
+ if (!dev->status_users)
+ ret = _uvc_status_start(dev, GFP_KERNEL);
+ if (!ret)
+ dev->status_users++;
+ mutex_unlock(&dev->status_lock);
+
+ return ret;
+}
+
+void uvc_status_put(struct uvc_device *dev)
+{
+ mutex_lock(&dev->status_lock);
+ if (dev->status_users == 1)
+ _uvc_status_stop(dev);
+ WARN_ON(!dev->status_users);
+ if (dev->status_users)
+ dev->status_users--;
+ mutex_unlock(&dev->status_lock);
+}
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index f4988f03640ae..97c5407f66032 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -628,20 +628,13 @@ static int uvc_v4l2_open(struct file *file)
return -ENOMEM;
}

- mutex_lock(&stream->dev->lock);
- if (stream->dev->users == 0) {
- ret = uvc_status_start(stream->dev, GFP_KERNEL);
- if (ret < 0) {
- mutex_unlock(&stream->dev->lock);
- usb_autopm_put_interface(stream->dev->intf);
- kfree(handle);
- return ret;
- }
+ ret = uvc_status_get(stream->dev);
+ if (ret) {
+ usb_autopm_put_interface(stream->dev->intf);
+ kfree(handle);
+ return ret;
}

- stream->dev->users++;
- mutex_unlock(&stream->dev->lock);
-
v4l2_fh_init(&handle->vfh, &stream->vdev);
v4l2_fh_add(&handle->vfh);
handle->chain = stream->chain;
@@ -670,10 +663,7 @@ static int uvc_v4l2_release(struct file *file)
kfree(handle);
file->private_data = NULL;

- mutex_lock(&stream->dev->lock);
- if (--stream->dev->users == 0)
- uvc_status_stop(stream->dev);
- mutex_unlock(&stream->dev->lock);
+ uvc_status_put(stream->dev);

usb_autopm_put_interface(stream->dev->intf);
return 0;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 6fb0a78b1b009..00b600eb058cc 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -555,8 +555,6 @@ struct uvc_device {

const struct uvc_device_info *info;

- struct mutex lock; /* Protects users */
- unsigned int users;
atomic_t nmappings;

/* Video control interface */
@@ -578,6 +576,8 @@ struct uvc_device {
struct usb_host_endpoint *int_ep;
struct urb *int_urb;
struct uvc_status *status;
+ struct mutex status_lock; /* Protects status_users */
+ unsigned int status_users;
bool flush_status;

struct input_dev *input;
@@ -744,8 +744,10 @@ int uvc_register_video_device(struct uvc_device *dev,
int uvc_status_init(struct uvc_device *dev);
void uvc_status_unregister(struct uvc_device *dev);
void uvc_status_cleanup(struct uvc_device *dev);
-int uvc_status_start(struct uvc_device *dev, gfp_t flags);
-void uvc_status_stop(struct uvc_device *dev);
+int uvc_status_resume(struct uvc_device *dev);
+void uvc_status_suspend(struct uvc_device *dev);
+int uvc_status_get(struct uvc_device *dev);
+void uvc_status_put(struct uvc_device *dev);

/* Controls */
extern const struct uvc_control_mapping uvc_ctrl_power_line_mapping_limited;

--
2.44.0.396.g6e790dbe36-goog