Re: [PATCH]saa7134-video.c: poll method lose race condition

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Am Montag, den 18.05.2009, 10:13 +0800 schrieb figo.zhang:
> saa7134-video.c: poll method lose race condition
> 
> 
> Signed-off-by: Figo.zhang <figo.zhang@xxxxxxxxxxxxx>
> --- 
> drivers/media/video/saa7134/saa7134-video.c |    9 ++++++---
>  1 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/video/saa7134/saa7134-video.c b/drivers/media/video/saa7134/saa7134-video.c
> index 493cad9..95733df 100644
> --- a/drivers/media/video/saa7134/saa7134-video.c
> +++ b/drivers/media/video/saa7134/saa7134-video.c
> @@ -1423,11 +1423,13 @@ video_poll(struct file *file, struct poll_table_struct *wait)
>  {
>  	struct saa7134_fh *fh = file->private_data;
>  	struct videobuf_buffer *buf = NULL;
> +	unsigned int rc = 0;
>  
>  	if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type)
>  		return videobuf_poll_stream(file, &fh->vbi, wait);
>  
>  	if (res_check(fh,RESOURCE_VIDEO)) {
> +		mutex_lock(&fh->cap.vb_lock);
>  		if (!list_empty(&fh->cap.stream))
>  			buf = list_entry(fh->cap.stream.next, struct videobuf_buffer, stream);
>  	} else {
> @@ -1446,13 +1448,14 @@ video_poll(struct file *file, struct poll_table_struct *wait)
>  	}
>  
>  	if (!buf)
> -		return POLLERR;
> +		rc = POLLERR;
>  
>  	poll_wait(file, &buf->done, wait);
>  	if (buf->state == VIDEOBUF_DONE ||
>  	    buf->state == VIDEOBUF_ERROR)
> -		return POLLIN|POLLRDNORM;
> -	return 0;
> +		rc = POLLIN|POLLRDNORM;
> +	mutex_unlock(&fh->cap.vb_lock);
> +	return rc;
>  
>  err:
>  	mutex_unlock(&fh->cap.vb_lock);
> 
> 

Can you please give some description on what your patch might do
something?

Or are you a robot?

Then, please give us your serial number, production year, and when we
can expect you are out of duty and replaced ;)

Cheers,
Hermann




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