[PATCH v8 51/53] media: v4l2: Add DELETE_BUFS ioctl

Benjamin Gaignard
2023-09-27T15:40:40Z

VIDIOC_DELETE_BUFS ioctl allows to delete buffers from a queue.
The number of buffers to delete in given by count field of
struct v4l2_delete_buffers and the range start at the index
specified in the same structure.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
version 8:
- Add V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS capabilities flag.
- Fix warnings in documentation.

.../userspace-api/media/v4l/user-func.rst | 1 +
.../media/v4l/vidioc-delete-bufs.rst | 80 +++++++++++++++++++
.../media/v4l/vidioc-reqbufs.rst | 1 +
.../media/common/videobuf2/videobuf2-core.c | 30 +++++++
.../media/common/videobuf2/videobuf2-v4l2.c | 20 +++++
drivers/media/v4l2-core/v4l2-dev.c | 1 +
drivers/media/v4l2-core/v4l2-ioctl.c | 17 ++++
include/media/v4l2-ioctl.h | 4 +
include/media/videobuf2-core.h | 12 +++
include/media/videobuf2-v4l2.h | 13 +++
include/uapi/linux/videodev2.h | 17 ++++
11 files changed, 196 insertions(+)
create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst

diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
index 15ff0bf7bbe6..3fd567695477 100644
--- a/Documentation/userspace-api/media/v4l/user-func.rst
+++ b/Documentation/userspace-api/media/v4l/user-func.rst
@@ -17,6 +17,7 @@ Function Reference
vidioc-dbg-g-chip-info
vidioc-dbg-g-register
vidioc-decoder-cmd
+ vidioc-delete-bufs
vidioc-dqevent
vidioc-dv-timings-cap
vidioc-encoder-cmd
diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
new file mode 100644
index 000000000000..4791df1395d6
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst
@@ -0,0 +1,80 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_DELETE_BUFS:
+
+************************
+ioctl VIDIOC_DELETE_BUFS
+************************
+
+Name
+====
+
+VIDIOC_DELETE_BUFS - Deletes buffers from a queue
+Drivers using this feature must expose the ``V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS``
+capability on the queue :c:func:`VIDIOC_REQBUFS` or :c:func:`VIDIOC_CREATE_BUFS`
+are invoked.
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_DELETE_BUFs
+
+``int ioctl(int fd, VIDIOC_DELETE_BUFs, struct v4l2_delete_buffers *argp)``
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :c:func:`open()`.
+
+``argp``
+ Pointer to struct :c:type:`v4l2_delete_buffers`.
+
+Description
+===========
+
+Applications can optionally call the :ref:`VIDIOC_DELETE_BUFS` ioctl to
+delete buffers from a queue.
+
+.. c:type:: v4l2_delete_buffers
+
+.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
+
+.. flat-table:: struct v4l2_delete_buffers
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 1 1 2
+
+ * - __u32
+ - ``index``
+ - The starting buffer index to delete.
+ * - __u32
+ - ``count``
+ - The number of buffers to be deleted with indices 'index' until 'index + count - 1'.
+ All buffers in this range must be valid and in DEQUEUED state.
+ In error case errno is set to ``EINVAL`` error code and index returns the index of
+ the invalid buffer.
+ If count and index are set to 0 :ref:`VIDIOC_DELETE_BUFS` will return 0.
+ * - __u32
+ - ``type``
+ - Type of the stream or buffers, this is the same as the struct
+ :c:type:`v4l2_format` ``type`` field. See
+ :c:type:`v4l2_buf_type` for valid values.
+ * - __u32
+ - ``reserved``\ [13]
+ - A place holder for future extensions. Drivers and applications
+ must set the array to zero.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.
+
+EBUSY
+ File I/O is in progress.
+
+EINVAL
+ The buffer ``index`` doesn't exist in the queue.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
index 0395187e1a5a..bcdf72dcbc22 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
@@ -121,6 +121,7 @@ aborting or finishing any DMA in progress, an implicit
.. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
.. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
.. _V4L2-BUF-CAP-SUPPORTS-SET-MAX-BUFS:
+.. _V4L2-BUF-CAP-SUPPORTS-DELETE-BUFS:

.. raw:: latex

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 3bf455f03461..98e72acab408 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -1664,6 +1664,36 @@ int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb)
}
EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);

+int vb2_core_delete_bufs(struct vb2_queue *q, unsigned int start, unsigned int count)
+{
+ unsigned int i, ret = 0;
+
+ if (start == 0 && count == 0)
+ return 0;
+
+ mutex_lock(&q->mmap_lock);
+
+ for (i = start; i < start + count && i < q->max_num_buffers; i++) {
+ struct vb2_buffer *vb = vb2_get_buffer(q, i);
+
+ if (!vb) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+ if (vb->state != VB2_BUF_STATE_DEQUEUED) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+ }
+ __vb2_queue_free(q, start, count);
+ dprintk(q, 2, "buffers deleted\n");
+
+unlock:
+ mutex_unlock(&q->mmap_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_core_delete_bufs);
+
/*
* vb2_start_streaming() - Attempt to start streaming.
* @q: videobuf2 queue
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 3d2affb00d19..98f2c1433678 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -696,6 +696,8 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
if (q->supports_requests)
*caps |= V4L2_BUF_CAP_SUPPORTS_REQUESTS;
#endif
+ if (q->supports_delete_bufs)
+ *caps |= V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS;
}

static void validate_memory_flags(struct vb2_queue *q,
@@ -753,6 +755,12 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
}
EXPORT_SYMBOL_GPL(vb2_prepare_buf);

+int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d)
+{
+ return vb2_core_delete_bufs(q, d->index, d->count);
+}
+EXPORT_SYMBOL_GPL(vb2_delete_bufs);
+
int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
{
unsigned requested_planes = 1;
@@ -1016,6 +1024,18 @@ EXPORT_SYMBOL_GPL(vb2_poll);

/* vb2 ioctl helpers */

+int vb2_ioctl_delete_bufs(struct file *file, void *priv,
+ struct v4l2_delete_buffers *p)
+{
+ struct video_device *vdev = video_devdata(file);
+
+ if (vb2_queue_is_busy(vdev->queue, file))
+ return -EBUSY;
+
+ return vb2_delete_bufs(vdev->queue, p);
+}
+EXPORT_SYMBOL_GPL(vb2_ioctl_delete_bufs);
+
int vb2_ioctl_reqbufs(struct file *file, void *priv,
struct v4l2_requestbuffers *p)
{
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index f81279492682..215654fd6581 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -720,6 +720,7 @@ static void determine_valid_ioctls(struct video_device *vdev)
SET_VALID_IOCTL(ops, VIDIOC_PREPARE_BUF, vidioc_prepare_buf);
SET_VALID_IOCTL(ops, VIDIOC_STREAMON, vidioc_streamon);
SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff);
+ SET_VALID_IOCTL(ops, VIDIOC_DELETE_BUFS, vidioc_delete_bufs);
}

if (is_vid || is_vbi || is_meta) {
diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 700db197e371..4514fa42c31f 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -489,6 +489,13 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
v4l_print_format(&p->format, write_only);
}

+static void v4l_print_delete_buffers(const void *arg, bool write_only)
+{
+ const struct v4l2_delete_buffers *p = arg;
+
+ pr_cont("index=%u, count=%u\n", p->index, p->count);
+}
+
static void v4l_print_streamparm(const void *arg, bool write_only)
{
const struct v4l2_streamparm *p = arg;
@@ -2160,6 +2167,15 @@ static int v4l_prepare_buf(const struct v4l2_ioctl_ops *ops,
return ret ? ret : ops->vidioc_prepare_buf(file, fh, b);
}

+static int v4l_delete_bufs(const struct v4l2_ioctl_ops *ops,
+ struct file *file, void *fh, void *arg)
+{
+ struct v4l2_delete_buffers *delete = arg;
+ int ret = check_fmt(file, delete->type);
+
+ return ret ? ret : ops->vidioc_delete_bufs(file, fh, delete);
+}
+
static int v4l_g_parm(const struct v4l2_ioctl_ops *ops,
struct file *file, void *fh, void *arg)
{
@@ -2909,6 +2925,7 @@ static const struct v4l2_ioctl_info v4l2_ioctls[] = {
IOCTL_INFO(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands, v4l_print_freq_band, 0),
IOCTL_INFO(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info, v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)),
IOCTL_INFO(VIDIOC_QUERY_EXT_CTRL, v4l_query_ext_ctrl, v4l_print_query_ext_ctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_query_ext_ctrl, id)),
+ IOCTL_INFO(VIDIOC_DELETE_BUFS, v4l_delete_bufs, v4l_print_delete_buffers, INFO_FL_PRIO | INFO_FL_QUEUE | INFO_FL_CLEAR(v4l2_delete_buffers, type)),
};
#define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)

diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index edb733f21604..55afbde54211 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -163,6 +163,8 @@ struct v4l2_fh;
* :ref:`VIDIOC_CREATE_BUFS <vidioc_create_bufs>` ioctl
* @vidioc_prepare_buf: pointer to the function that implements
* :ref:`VIDIOC_PREPARE_BUF <vidioc_prepare_buf>` ioctl
+ * @vidioc_delete_bufs: pointer to the function that implements
+ * :ref:`VIDIOC_DELETE_BUFS <vidioc_delete_bufs>` ioctl
* @vidioc_overlay: pointer to the function that implements
* :ref:`VIDIOC_OVERLAY <vidioc_overlay>` ioctl
* @vidioc_g_fbuf: pointer to the function that implements
@@ -422,6 +424,8 @@ struct v4l2_ioctl_ops {
struct v4l2_create_buffers *b);
int (*vidioc_prepare_buf)(struct file *file, void *fh,
struct v4l2_buffer *b);
+ int (*vidioc_delete_bufs)(struct file *file, void *fh,
+ struct v4l2_delete_buffers *d);

int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i);
int (*vidioc_g_fbuf)(struct file *file, void *fh,
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index fc1fcd8faa64..29c34947098e 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -507,6 +507,7 @@ struct vb2_buf_ops {
* @supports_requests: this queue supports the Request API.
* @requires_requests: this queue requires the Request API. If this is set to 1,
* then supports_requests must be set to 1 as well.
+ * @supports_delete_bufs: this queue supports DELETE_BUFS ioctl.
* @uses_qbuf: qbuf was used directly for this queue. Set to 1 the first
* time this is called. Set to 0 when the queue is canceled.
* If this is 1, then you cannot queue buffers from a request.
@@ -595,6 +596,7 @@ struct vb2_queue {
unsigned int quirk_poll_must_check_waiting_for_buffers:1;
unsigned int supports_requests:1;
unsigned int requires_requests:1;
+ unsigned int supports_delete_bufs:1;
unsigned int uses_qbuf:1;
unsigned int uses_requests:1;
unsigned int allow_cache_hints:1;
@@ -846,6 +848,16 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
*/
int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);

+/**
+ * vb2_core_delete_bufs() -
+ * @q: pointer to &struct vb2_queue with videobuf2 queue.
+ * @start: first index of the range of buffers to delete.
+ * @count: number of buffers to delete.
+ *
+ * Return: returns zero on success; an error code otherwise.
+ */
+int vb2_core_delete_bufs(struct vb2_queue *q, unsigned int start, unsigned int count);
+
/**
* vb2_core_qbuf() - Queue a buffer from userspace
*
diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
index 5a845887850b..79cea8459f52 100644
--- a/include/media/videobuf2-v4l2.h
+++ b/include/media/videobuf2-v4l2.h
@@ -118,6 +118,17 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
*/
int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
struct v4l2_buffer *b);
+/**
+ * vb2_delete_bufs() - Delete buffers from the queue
+ *
+ * @q: pointer to &struct vb2_queue with videobuf2 queue.
+ * @d: delete parameter, passed from userspace to
+ * &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver
+ *
+ * The return values from this function are intended to be directly returned
+ * from &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver.
+ */
+int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d);

/**
* vb2_qbuf() - Queue a buffer from userspace
@@ -334,6 +345,8 @@ int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i);
int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i);
int vb2_ioctl_expbuf(struct file *file, void *priv,
struct v4l2_exportbuffer *p);
+int vb2_ioctl_delete_bufs(struct file *file, void *priv,
+ struct v4l2_delete_buffers *p);

/* struct v4l2_file_operations helpers */

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index b0dbb1be728c..49c50e31c2b3 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -1035,6 +1035,7 @@ struct v4l2_requestbuffers {
#define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF (1 << 5)
#define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS (1 << 6)
#define V4L2_BUF_CAP_SUPPORTS_SET_MAX_BUFS (1 << 7)
+#define V4L2_BUF_CAP_SUPPORTS_DELETE_BUFS (1 << 8)

/**
* struct v4l2_plane - plane info for multi-planar buffers
@@ -2621,6 +2622,20 @@ struct v4l2_create_buffers {
__u32 reserved[5];
};

+/**
+ * struct v4l2_delete_buffers - VIDIOC_DELETE_BUFS argument
+ * @index: the first buffer to be deleted
+ * @count: number of buffers to delete
+ * @type: enum v4l2_buf_type
+ * @reserved: future extensions
+ */
+struct v4l2_delete_buffers {
+ __u32 index;
+ __u32 count;
+ __u32 type;
+ __u32 reserved[13];
+};
+
/*
* I O C T L C O D E S F O R V I D E O D E V I C E S
*
@@ -2720,6 +2735,8 @@ struct v4l2_create_buffers {
#define VIDIOC_DBG_G_CHIP_INFO _IOWR('V', 102, struct v4l2_dbg_chip_info)

#define VIDIOC_QUERY_EXT_CTRL _IOWR('V', 103, struct v4l2_query_ext_ctrl)
+#define VIDIOC_DELETE_BUFS _IOWR('V', 104, struct v4l2_delete_buffers)
+

/* Reminder: when adding new ioctls please add support for them to
drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */