On Tue, Mar 21, 2023 at 11:28:52AM +0100, Benjamin Gaignard wrote:
> VIDIOC_DELETE_BUF ioctl allows to delete a buffer from a queue.
>
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
> .../userspace-api/media/v4l/user-func.rst | 1 +
> .../media/v4l/vidioc-delete-buf.rst | 51 ++++++++++++++++
> .../media/common/videobuf2/videobuf2-core.c | 59 ++++++++++++++++++-
> .../media/common/videobuf2/videobuf2-v4l2.c | 6 ++
> drivers/media/v4l2-core/v4l2-dev.c | 1 +
> drivers/media/v4l2-core/v4l2-ioctl.c | 10 ++++
> include/media/v4l2-ioctl.h | 4 ++
> include/media/videobuf2-core.h | 9 +++
> include/media/videobuf2-v4l2.h | 11 ++++
> include/uapi/linux/videodev2.h | 1 +
> 10 files changed, 152 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst
>
> diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
> index 228c1521f190..93e0a6a117fc 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-buf
> vidioc-dqevent
> vidioc-dv-timings-cap
> vidioc-encoder-cmd
> diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst
> new file mode 100644
> index 000000000000..0e7ce58f91bc
> --- /dev/null
> +++ b/Documentation/userspace-api/media/v4l/vidioc-delete-buf.rst
> @@ -0,0 +1,51 @@
> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
> +.. c:namespace:: V4L
> +
> +.. _VIDIOC_DELETE_BUF:
> +
> +************************
> +ioctl VIDIOC_DELETE_BUF
> +************************
> +
> +Name
> +====
> +
> +VIDIOC_DELETE_BUF - Delete a buffer from a queue
> +
> +Synopsis
> +========
> +
> +.. c:macro:: VIDIOC_DELETE_BUF
> +
> +``int ioctl(int fd, VIDIOC_DELETE_BUF, struct v4l2_buffer *argp)``
> +
> +Arguments
> +=========
> +
> +``fd``
> + File descriptor returned by :c:func:`open()`.
> +
> +``argp``
> + Pointer to struct :c:type:`v4l2_buffer`.
Would struct v4l2_create_buffers make more sense here? With it, we could
actually make this ioctl VIDIOC_DELETE_BUF*S*, consistently with
VIDIOC_CREATE_BUF*S* and allow the user space to remove a block of buffers
the same way it created a block of buffers in the first place.
> +
> +Description
> +===========
> +
> +Applications can optionally call the :ref:`VIDIOC_DELETE_BUF` ioctl to
> +delete a buffer from a queue.
> +
> +The struct :c:type:`v4l2_buffer` structure is specified in
> +:ref:`buffer`.
> +
> +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/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index 3c6ced360770..ec241d726fe6 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -401,6 +401,24 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
> vb->skip_cache_sync_on_finish = 1;
> }
>
> +/*
> + * __vb2_queue_get_free_index() - find a free index in the queue for vb2 buffer.
> + *
> + * Returns an index for vb2 buffer.
> + */
> +static int __vb2_queue_get_free_index(struct vb2_queue *q)
> +{
> + int i;
> +
> + spin_lock(&q->bufs_lock);
> + for (i = 0; i < q->max_num_bufs; i++)
> + if (!q->bufs[i])
> + break;
> + spin_unlock(&q->bufs_lock);
> +
> + return i;
> +}
Another reason to go with XArray, so that we don't have to open code
index reclaim.
> +
> /*
> * __vb2_queue_alloc() - allocate vb2 buffer structures and (for MMAP type)
> * video buffer memory for all buffers/planes on the queue and initializes the
> @@ -427,7 +445,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
> vb->state = VB2_BUF_STATE_DEQUEUED;
> vb->vb2_queue = q;
> vb->num_planes = num_planes;
> - vb->index = q->num_buffers + buffer;
> + vb->index = __vb2_queue_get_free_index(q);
> vb->type = q->type;
> vb->memory = memory;
> init_buffer_cache_hints(q, vb);
> @@ -1570,6 +1588,45 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
> }
> EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
>
> +int vb2_core_delete_buf(struct vb2_queue *q, unsigned int index)
> +{
> + struct vb2_buffer *vb;
> +
> + vb = vb2_get_buffer(q, index);
> + if (!vb) {
> + dprintk(q, 1, "invalid buffer index %d\n", index);
> + return -EINVAL;
> + }
> +
> + if (vb->state == VB2_BUF_STATE_QUEUED) {
How about other states? I'd probably only allow this when the state is
DEQUEUED for simplicity. Is there a need to allow deleting buffers in
other states?
Also, do we need to synchronize this with other contexts which could change
the buffer state?
> + dprintk(q, 1, "can't delete queued buffer index %d\n", index);
> + return -EINVAL;
> + }
> +
Don't we also need to hold q->mmap_lock to prevent racing with an attempt
to mmap the buffer?
> + if (vb && vb->planes[0].mem_priv)
nit: At this point it's not possible for vb to be NULL, since we already
ruled that out a few lines above.
> + call_void_vb_qop(vb, buf_cleanup, vb);
> +
> + /* Free MMAP buffers or release USERPTR buffers */
> + if (q->memory == VB2_MEMORY_MMAP)
> + __vb2_buf_mem_free(vb);
> + else if (q->memory == VB2_MEMORY_DMABUF)
> + __vb2_buf_dmabuf_put(vb);
> + else
> + __vb2_buf_userptr_put(vb);
> +
> + vb2_queue_remove_buffer(q, vb);
> + kfree(vb);
> +
> + q->num_buffers--;
> + if (!q->num_buffers) {
> + q->memory = VB2_MEMORY_UNKNOWN;
> + INIT_LIST_HEAD(&q->queued_list);
> + }
Would it make sense to refactor __vb2_queue_free() instead to take a
range of buffer indexes rather than duplicating the code here?
Best regards,
Tomasz
@@ -17,6 +17,7 @@ Function Reference
vidioc-dbg-g-chip-info
vidioc-dbg-g-register
vidioc-decoder-cmd
+ vidioc-delete-buf
vidioc-dqevent
vidioc-dv-timings-cap
vidioc-encoder-cmd
new file mode 100644
@@ -0,0 +1,51 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+.. c:namespace:: V4L
+
+.. _VIDIOC_DELETE_BUF:
+
+************************
+ioctl VIDIOC_DELETE_BUF
+************************
+
+Name
+====
+
+VIDIOC_DELETE_BUF - Delete a buffer from a queue
+
+Synopsis
+========
+
+.. c:macro:: VIDIOC_DELETE_BUF
+
+``int ioctl(int fd, VIDIOC_DELETE_BUF, struct v4l2_buffer *argp)``
+
+Arguments
+=========
+
+``fd``
+ File descriptor returned by :c:func:`open()`.
+
+``argp``
+ Pointer to struct :c:type:`v4l2_buffer`.
+
+Description
+===========
+
+Applications can optionally call the :ref:`VIDIOC_DELETE_BUF` ioctl to
+delete a buffer from a queue.
+
+The struct :c:type:`v4l2_buffer` structure is specified in
+:ref:`buffer`.
+
+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.
@@ -401,6 +401,24 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
vb->skip_cache_sync_on_finish = 1;
}
+/*
+ * __vb2_queue_get_free_index() - find a free index in the queue for vb2 buffer.
+ *
+ * Returns an index for vb2 buffer.
+ */
+static int __vb2_queue_get_free_index(struct vb2_queue *q)
+{
+ int i;
+
+ spin_lock(&q->bufs_lock);
+ for (i = 0; i < q->max_num_bufs; i++)
+ if (!q->bufs[i])
+ break;
+ spin_unlock(&q->bufs_lock);
+
+ return i;
+}
+
/*
* __vb2_queue_alloc() - allocate vb2 buffer structures and (for MMAP type)
* video buffer memory for all buffers/planes on the queue and initializes the
@@ -427,7 +445,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
vb->state = VB2_BUF_STATE_DEQUEUED;
vb->vb2_queue = q;
vb->num_planes = num_planes;
- vb->index = q->num_buffers + buffer;
+ vb->index = __vb2_queue_get_free_index(q);
vb->type = q->type;
vb->memory = memory;
init_buffer_cache_hints(q, vb);
@@ -1570,6 +1588,45 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
}
EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
+int vb2_core_delete_buf(struct vb2_queue *q, unsigned int index)
+{
+ struct vb2_buffer *vb;
+
+ vb = vb2_get_buffer(q, index);
+ if (!vb) {
+ dprintk(q, 1, "invalid buffer index %d\n", index);
+ return -EINVAL;
+ }
+
+ if (vb->state == VB2_BUF_STATE_QUEUED) {
+ dprintk(q, 1, "can't delete queued buffer index %d\n", index);
+ return -EINVAL;
+ }
+
+ if (vb && vb->planes[0].mem_priv)
+ call_void_vb_qop(vb, buf_cleanup, vb);
+
+ /* Free MMAP buffers or release USERPTR buffers */
+ if (q->memory == VB2_MEMORY_MMAP)
+ __vb2_buf_mem_free(vb);
+ else if (q->memory == VB2_MEMORY_DMABUF)
+ __vb2_buf_dmabuf_put(vb);
+ else
+ __vb2_buf_userptr_put(vb);
+
+ vb2_queue_remove_buffer(q, vb);
+ kfree(vb);
+
+ q->num_buffers--;
+ if (!q->num_buffers) {
+ q->memory = VB2_MEMORY_UNKNOWN;
+ INIT_LIST_HEAD(&q->queued_list);
+ }
+
+ dprintk(q, 2, "buffer %d deleted\n", index);
+ return 0;
+}
+
/*
* vb2_start_streaming() - Attempt to start streaming.
* @q: videobuf2 queue
@@ -742,6 +742,12 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
}
EXPORT_SYMBOL_GPL(vb2_prepare_buf);
+int vb2_delete_buf(struct vb2_queue *q, struct v4l2_buffer *b)
+{
+ return vb2_core_delete_buf(q, b->index);
+}
+EXPORT_SYMBOL_GPL(vb2_delete_buf);
+
int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
{
unsigned requested_planes = 1;
@@ -719,6 +719,7 @@ 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_BUF, vidioc_delete_buf);
}
if (is_vid || is_vbi || is_meta) {
@@ -2152,6 +2152,15 @@ 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_buf(const struct v4l2_ioctl_ops *ops,
+ struct file *file, void *fh, void *arg)
+{
+ struct v4l2_buffer *b = arg;
+ int ret = check_fmt(file, b->type);
+
+ return ret ? ret : ops->vidioc_delete_buf(file, fh, b);
+}
+
static int v4l_g_parm(const struct v4l2_ioctl_ops *ops,
struct file *file, void *fh, void *arg)
{
@@ -2902,6 +2911,7 @@ 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_BUF, v4l_delete_buf, v4l_print_buffer, INFO_FL_QUEUE),
};
#define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
@@ -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_buf: pointer to the function that implements
+ * :ref:`VIDIOC_DELETE_BUF <vidioc_delete_buf>` 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_buf)(struct file *file, void *fh,
+ struct v4l2_buffer *b);
int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i);
int (*vidioc_g_fbuf)(struct file *file, void *fh,
@@ -847,6 +847,15 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
*/
int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);
+/**
+ * vb2_core_delete_buf() -
+ * @q: pointer to &struct vb2_queue with videobuf2 queue.
+ * @index: id number of the buffer.
+ *
+ * Return: returns zero on success; an error code otherwise.
+ */
+int vb2_core_delete_buf(struct vb2_queue *q, unsigned int index);
+
/**
* vb2_core_qbuf() - Queue a buffer from userspace
*
@@ -114,6 +114,17 @@ 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_buf() - Delete the buffer from the queue
+ *
+ * @q: pointer to &struct vb2_queue with videobuf2 queue.
+ * @b: buffer structure passed from userspace to
+ * &v4l2_ioctl_ops->vidioc_delete_buf handler in driver
+ *
+ * The return values from this function are intended to be directly returned
+ * from &v4l2_ioctl_ops->vidioc_delete_buf handler in driver.
+ */
+int vb2_delete_buf(struct vb2_queue *q, struct v4l2_buffer *b);
/**
* vb2_qbuf() - Queue a buffer from userspace
@@ -2681,6 +2681,7 @@ struct v4l2_create_buffers {
#define VIDIOC_QUERY_DV_TIMINGS _IOR('V', 99, struct v4l2_dv_timings)
#define VIDIOC_DV_TIMINGS_CAP _IOWR('V', 100, struct v4l2_dv_timings_cap)
#define VIDIOC_ENUM_FREQ_BANDS _IOWR('V', 101, struct v4l2_frequency_band)
+#define VIDIOC_DELETE_BUF _IOWR('V', 102, struct v4l2_buffer)
/*
* Experimental, meant for debugging, testing and internal use.