Hi Hans,
On Tue, Jan 16, 2024 at 11:05 PM Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote:
>
> Several functions implementing VIDIOC_REQBUFS and _CREATE_BUFS all use almost
> the same code to fill in the flags and capability fields. Refactor this into a
> new vb2_set_flags_and_caps() function that replaces the old fill_buf_caps()
> and validate_memory_flags() functions.
>
> This also fixes a bug where vb2_ioctl_create_bufs() would not set the
> V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS cap and also not fill in the
> max_num_buffers field.
>
> Fixes: d055a76c0065 ("media: core: Report the maximum possible number of buffers for the queue")
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
> ---
> .../media/common/videobuf2/videobuf2-v4l2.c | 55 +++++++++----------
> 1 file changed, 26 insertions(+), 29 deletions(-)
>
Thanks for the patch! Please check my comments inline.
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 54d572c3b515..c575198e8354 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -671,8 +671,20 @@ int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
> }
> EXPORT_SYMBOL(vb2_querybuf);
>
> -static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
> +static void vb2_set_flags_and_caps(struct vb2_queue *q, u32 memory,
> + u32 *flags, u32 *caps, u32 *max_num_bufs)
> {
> + if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
> + /*
> + * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
> + * but in order to avoid bugs we zero out all bits.
> + */
> + *flags = 0;
> + } else {
> + /* Clear all unknown flags. */
> + *flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
> + }
> +
> *caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
> if (q->io_modes & VB2_MMAP)
> *caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
> @@ -686,21 +698,9 @@ static void fill_buf_caps(struct vb2_queue *q, u32 *caps)
> *caps |= V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS;
> if (q->supports_requests)
> *caps |= V4L2_BUF_CAP_SUPPORTS_REQUESTS;
> -}
> -
> -static void validate_memory_flags(struct vb2_queue *q,
> - int memory,
> - u32 *flags)
> -{
> - if (!q->allow_cache_hints || memory != V4L2_MEMORY_MMAP) {
> - /*
> - * This needs to clear V4L2_MEMORY_FLAG_NON_COHERENT only,
> - * but in order to avoid bugs we zero out all bits.
> - */
> - *flags = 0;
> - } else {
> - /* Clear all unknown flags. */
> - *flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
> + if (max_num_bufs) {
> + *max_num_bufs = q->max_num_buffers;
> + *caps |= V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS;
> }
> }
>
> @@ -709,8 +709,8 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> int ret = vb2_verify_memory_type(q, req->memory, req->type);
> u32 flags = req->flags;
I think we have a bug here, we check the memory type, but just let the
code continue even if it's invalid.
>
> - fill_buf_caps(q, &req->capabilities);
> - validate_memory_flags(q, req->memory, &flags);
> + vb2_set_flags_and_caps(q, req->memory, &flags,
> + &req->capabilities, NULL);
> req->flags = flags;
> return ret ? ret : vb2_core_reqbufs(q, req->memory,
> req->flags, &req->count);
> @@ -751,11 +751,9 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
> int ret = vb2_verify_memory_type(q, create->memory, f->type);
> unsigned i;
>
Ditto.
> - fill_buf_caps(q, &create->capabilities);
> - validate_memory_flags(q, create->memory, &create->flags);
> create->index = vb2_get_num_buffers(q);
> - create->max_num_buffers = q->max_num_buffers;
> - create->capabilities |= V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS;
> + vb2_set_flags_and_caps(q, create->memory, &create->flags,
> + &create->capabilities, &create->max_num_buffers);
> if (create->count == 0)
> return ret != -EBUSY ? ret : 0;
>
> @@ -1006,8 +1004,8 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,
> int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);
> u32 flags = p->flags;
>
> - fill_buf_caps(vdev->queue, &p->capabilities);
> - validate_memory_flags(vdev->queue, p->memory, &flags);
> + vb2_set_flags_and_caps(vdev->queue, p->memory, &flags,
> + &p->capabilities, NULL);
Could we just call vb2_reqbufs() instead of vb2_core_reqbufs() and
avoid all the duplicate checks?
> p->flags = flags;
> if (res)
> return res;
> @@ -1026,12 +1024,11 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
> struct v4l2_create_buffers *p)
> {
> struct video_device *vdev = video_devdata(file);
> - int res = vb2_verify_memory_type(vdev->queue, p->memory,
> - p->format.type);
> + int res = vb2_verify_memory_type(vdev->queue, p->memory, p->format.type);
>
> - p->index = vdev->queue->num_buffers;
> - fill_buf_caps(vdev->queue, &p->capabilities);
> - validate_memory_flags(vdev->queue, p->memory, &p->flags);
> + p->index = vb2_get_num_buffers(vdev->queue);
> + vb2_set_flags_and_caps(vdev->queue, p->memory, &p->flags,
> + &p->capabilities, &p->max_num_buffers);
This function in fact already calls vb2_create_bufs() which includes
all the checks above, except the one for vb2_queue_is_bus() that
continues down below, so maybe we can just remove them?
Best regards,
Tomasz
> /*
> * If count == 0, then just check if memory and type are valid.
> * Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
> --
> 2.42.0
>
>
