v4l: vb2: Avoid double WARN_ON when stopping streaming

The __vb2_queue_cancel function marks the queue as not streaming and
then WARNs when buffers are still owned by the driver. It proceeds to
complete all active buffers by calling vb2_buffer_done with the new
buffer state set to VB2_BUF_STATE_ERROR in that case. This triggers
another WARN_ON due to as new state not being VB2_BUF_STATE_QUEUED while
the queue is not streaming.

Check buffer ownership and complete all active buffers before marking
the queue as not streaming to avoid the double WARN_on.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/media/v4l2-core/videobuf2-core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
  

On 04/21/2014 01:55 AM, Laurent Pinchart wrote:
> The __vb2_queue_cancel function marks the queue as not streaming and
> then WARNs when buffers are still owned by the driver. It proceeds to
> complete all active buffers by calling vb2_buffer_done with the new
> buffer state set to VB2_BUF_STATE_ERROR in that case. This triggers
> another WARN_ON due to as new state not being VB2_BUF_STATE_QUEUED while
> the queue is not streaming.
> 
> Check buffer ownership and complete all active buffers before marking
> the queue as not streaming to avoid the double WARN_on.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>

Thanks!

	Hans

> ---
>  drivers/media/v4l2-core/videobuf2-core.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 6ab13b7..ab88c09 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -2028,9 +2028,6 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>  	 */
>  	if (q->start_streaming_called)
>  		call_qop(q, stop_streaming, q);
> -	q->streaming = 0;
> -	q->start_streaming_called = 0;
> -	q->queued_count = 0;
>  
>  	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
>  		for (i = 0; i < q->num_buffers; ++i)
> @@ -2040,6 +2037,10 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>  		WARN_ON(atomic_read(&q->owned_by_drv_count));
>  	}
>  
> +	q->streaming = 0;
> +	q->start_streaming_called = 0;
> +	q->queued_count = 0;
> +
>  	/*
>  	 * Remove all buffers from videobuf's list...
>  	 */
> 

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