Re: [PATCH v3 22/33] omap3isp: Assume media_entity_pipeline_start may fail

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thanks for the patch.

On Monday 20 February 2012 03:57:01 Sakari Ailus wrote:
> Since media_entity_pipeline_start() now does link validation, it may
> actually fail. Perform the error handling.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
> ---
>  drivers/media/video/omap3isp/ispvideo.c |   20 ++++++++++++--------
>  1 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/video/omap3isp/ispvideo.c
> b/drivers/media/video/omap3isp/ispvideo.c index c191f13..17522db 100644
> --- a/drivers/media/video/omap3isp/ispvideo.c
> +++ b/drivers/media/video/omap3isp/ispvideo.c
> @@ -993,14 +993,16 @@ isp_video_streamon(struct file *file, void *fh, enum
> v4l2_buf_type type) */
>  	pipe = video->video.entity.pipe
>  	     ? to_isp_pipeline(&video->video.entity) : &video->pipe;
> -	media_entity_pipeline_start(&video->video.entity, &pipe->pipe);
> +	ret = media_entity_pipeline_start(&video->video.entity, &pipe->pipe);
> +	if (ret < 0)
> +		goto err_media_entity_pipeline_start;
> 
>  	/* Verify that the currently configured format matches the output of
>  	 * the connected subdev.
>  	 */
>  	ret = isp_video_check_format(video, vfh);
>  	if (ret < 0)
> -		goto error;
> +		goto err_isp_video_check_format;
> 
>  	video->bpl_padding = ret;
>  	video->bpl_value = vfh->format.fmt.pix.bytesperline;
> @@ -1017,7 +1019,7 @@ isp_video_streamon(struct file *file, void *fh, enum
> v4l2_buf_type type) } else {
>  		if (far_end == NULL) {
>  			ret = -EPIPE;
> -			goto error;
> +			goto err_isp_video_check_format;
>  		}
> 
>  		state = ISP_PIPELINE_STREAM_INPUT | ISP_PIPELINE_IDLE_INPUT;
> @@ -1032,7 +1034,7 @@ isp_video_streamon(struct file *file, void *fh, enum
> v4l2_buf_type type) /* Validate the pipeline and update its state. */
>  	ret = isp_video_validate_pipeline(pipe);
>  	if (ret < 0)
> -		goto error;
> +		goto err_isp_video_check_format;
> 
>  	pipe->error = false;
> 
> @@ -1054,7 +1056,7 @@ isp_video_streamon(struct file *file, void *fh, enum
> v4l2_buf_type type)
> 
>  	ret = omap3isp_video_queue_streamon(&vfh->queue);
>  	if (ret < 0)
> -		goto error;
> +		goto err_isp_video_check_format;
> 
>  	/* In sensor-to-memory mode, the stream can be started synchronously
>  	 * to the stream on command. In memory-to-memory mode, it will be
> @@ -1064,19 +1066,21 @@ isp_video_streamon(struct file *file, void *fh, enum
> v4l2_buf_type type) ret = omap3isp_pipeline_set_stream(pipe,
>  					      ISP_PIPELINE_STREAM_CONTINUOUS);
>  		if (ret < 0)
> -			goto error;
> +			goto err_omap3isp_set_stream;
>  		spin_lock_irqsave(&video->queue->irqlock, flags);
>  		if (list_empty(&video->dmaqueue))
>  			video->dmaqueue_flags |= ISP_VIDEO_DMAQUEUE_UNDERRUN;
>  		spin_unlock_irqrestore(&video->queue->irqlock, flags);
>  	}
> 
> -error:
>  	if (ret < 0) {
> +err_omap3isp_set_stream:
>  		omap3isp_video_queue_streamoff(&vfh->queue);
> +err_isp_video_check_format:
> +		media_entity_pipeline_stop(&video->video.entity);
> +err_media_entity_pipeline_start:
>  		if (video->isp->pdata->set_constraints)
>  			video->isp->pdata->set_constraints(video->isp, false);
> -		media_entity_pipeline_stop(&video->video.entity);
>  		/* The DMA queue must be emptied here, otherwise CCDC interrupts
>  		 * that will get triggered the next time the CCDC is powered up
>  		 * will try to access buffers that might have been freed but

As you add error labels, you can remove the if (ret < 0) test and move error 
handling to a separate block. set_constraint() should be called before 
media_entity_pipeline_stop() in that case. Another option is to leave error 
handling untouched, and to return directly when media_entity_pipeline_start() 
fails (after unlocking the mutex of course).

-- 
Regards,

Laurent Pinchart