On Mon, 4 Jul 2022 at 11:44, Vladimir Zapolskiy
<vladimir.zapolskiy@xxxxxxxxxx> wrote:
>
> It is required to return the received buffers, if streaming can not be
> started. For instance media_pipeline_start() may fail with EPIPE, if
> a link validation between entities is not passed, and in such a case
> a user gets a kernel warning:
>
> WARNING: CPU: 1 PID: 520 at drivers/media/common/videobuf2/videobuf2-core.c:1592 vb2_start_streaming+0xec/0x160
> <snip>
> Call trace:
> vb2_start_streaming+0xec/0x160
> vb2_core_streamon+0x9c/0x1a0
> vb2_ioctl_streamon+0x68/0xbc
> v4l_streamon+0x30/0x3c
> __video_do_ioctl+0x184/0x3e0
> video_usercopy+0x37c/0x7b0
> video_ioctl2+0x24/0x40
> v4l2_ioctl+0x4c/0x70
>
> The fix is to correct the error path in video_start_streaming() of camss.
>
> Fixes: 0ac2586c410f ("media: camss: Add files which handle the video device nodes")
> Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@xxxxxxxxxx>
> ---
> drivers/media/platform/qcom/camss/camss-video.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/qcom/camss/camss-video.c b/drivers/media/platform/qcom/camss/camss-video.c
> index b5f12ec5c50c..d272ffa02112 100644
> --- a/drivers/media/platform/qcom/camss/camss-video.c
> +++ b/drivers/media/platform/qcom/camss/camss-video.c
> @@ -495,7 +495,7 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
>
> ret = media_pipeline_start(&vdev->entity, &video->pipe);
> if (ret < 0)
> - return ret;
> + goto flush_buffers;
>
> ret = video_check_format(video);
> if (ret < 0)
> @@ -524,6 +524,7 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
> error:
> media_pipeline_stop(&vdev->entity);
>
> +flush_buffers:
> video->ops->flush_buffers(video, VB2_BUF_STATE_QUEUED);
>
> return ret;
> --
> 2.33.0
>
Reviewed-by: Robert Foss <robert.foss@xxxxxxxxxx>
