On Mon, 2009-05-18 at 05:07 +0200, hermann pitton wrote:
> 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
>
>
>
hi, I just using the saa7134 chip to do a video capture card. The
saa7134 driver in linux kernel, i found that the poll method have lose
race condition for "RESOURCE_VIDEO". It have better to add a mutex lock.
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