Message ID | 1243751538.3425.6.camel@myhost (mailing list archive) |
---|---|
State | Superseded |
Headers | show |
On Sun, 31 May 2009, Figo.zhang wrote: > bttv-driver.c,cx23885-video.c,cx88-video.c: poll method lose race condition for capture video. Please use patch titles that are not so long. It would be nice if you could describe this race condition. > > Signed-off-by: Figo.zhang <figo1802@gmail.com> > --- > drivers/media/video/bt8xx/bttv-driver.c | 7 +++++-- > drivers/media/video/cx23885/cx23885-video.c | 15 +++++++++++---- > drivers/media/video/cx88/cx88-video.c | 13 ++++++++++--- > 3 files changed, 26 insertions(+), 9 deletions(-) > > diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c > index 23b7499..9cadfcc 100644 > --- a/drivers/media/video/bt8xx/bttv-driver.c > +++ b/drivers/media/video/bt8xx/bttv-driver.c > @@ -3152,6 +3152,7 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) > struct bttv_fh *fh = file->private_data; > struct bttv_buffer *buf; > enum v4l2_field field; > + unsigned int rc = 0; > > if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) { > if (!check_alloc_btres(fh->btv,fh,RESOURCE_VBI)) > @@ -3160,6 +3161,7 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) > } > > if (check_btres(fh,RESOURCE_VIDEO_STREAM)) { > + mutex_lock(&fh->cap.vb_lock); > /* streaming capture */ > if (list_empty(&fh->cap.stream)) > return POLLERR; Won't you return with the mutex held here? > @@ -3191,8 +3193,9 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) > poll_wait(file, &buf->vb.done, wait); > if (buf->vb.state == VIDEOBUF_DONE || > buf->vb.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); > return POLLERR; I think the logic for these changes will be cleaner to do something like this: { unsigned int rc = POLLERR; if (some error); goto done; if (other error) goto done; if (buf->vb.state == VIDEOBUF_DONE || buf->vb.state == VIDEOBUF_ERROR) rc = POLLIN|POLLRDNORM; else rc = 0; done: mutex_unlock(&fh->vidq.vb_lock); return rc; } -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c index 23b7499..9cadfcc 100644 --- a/drivers/media/video/bt8xx/bttv-driver.c +++ b/drivers/media/video/bt8xx/bttv-driver.c @@ -3152,6 +3152,7 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) struct bttv_fh *fh = file->private_data; struct bttv_buffer *buf; enum v4l2_field field; + unsigned int rc = 0; if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) { if (!check_alloc_btres(fh->btv,fh,RESOURCE_VBI)) @@ -3160,6 +3161,7 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) } if (check_btres(fh,RESOURCE_VIDEO_STREAM)) { + mutex_lock(&fh->cap.vb_lock); /* streaming capture */ if (list_empty(&fh->cap.stream)) return POLLERR; @@ -3191,8 +3193,9 @@ static unsigned int bttv_poll(struct file *file, poll_table *wait) poll_wait(file, &buf->vb.done, wait); if (buf->vb.state == VIDEOBUF_DONE || buf->vb.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); return POLLERR; diff --git a/drivers/media/video/cx23885/cx23885-video.c b/drivers/media/video/cx23885/cx23885-video.c index 68068c6..386ad86 100644 --- a/drivers/media/video/cx23885/cx23885-video.c +++ b/drivers/media/video/cx23885/cx23885-video.c @@ -796,6 +796,7 @@ static unsigned int video_poll(struct file *file, { struct cx23885_fh *fh = file->private_data; struct cx23885_buffer *buf; + unsigned int rc = 0; if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) { if (!res_get(fh->dev, fh, RESOURCE_VBI)) @@ -803,23 +804,29 @@ static unsigned int video_poll(struct file *file, return videobuf_poll_stream(file, &fh->vbiq, wait); } + mutex_lock(&fh->vidq.vb_lock); if (res_check(fh, RESOURCE_VIDEO)) { /* streaming capture */ if (list_empty(&fh->vidq.stream)) - return POLLERR; + goto err; buf = list_entry(fh->vidq.stream.next, struct cx23885_buffer, vb.stream); } else { /* read() capture */ buf = (struct cx23885_buffer *)fh->vidq.read_buf; if (NULL == buf) - return POLLERR; + goto err; } poll_wait(file, &buf->vb.done, wait); if (buf->vb.state == VIDEOBUF_DONE || buf->vb.state == VIDEOBUF_ERROR) - return POLLIN|POLLRDNORM; - return 0; + rc = POLLIN|POLLRDNORM; + mutex_unlock(&fh->vidq.vb_lock); + return rc; + +err: + mutex_unlock(&fh->vidq.vb_lock); + return POLLERR; } static int video_release(struct file *file) diff --git a/drivers/media/video/cx88/cx88-video.c b/drivers/media/video/cx88/cx88-video.c index b993d42..f778d15 100644 --- a/drivers/media/video/cx88/cx88-video.c +++ b/drivers/media/video/cx88/cx88-video.c @@ -869,6 +869,7 @@ video_poll(struct file *file, struct poll_table_struct *wait) { struct cx8800_fh *fh = file->private_data; struct cx88_buffer *buf; + unsigned int rc = 0; if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) { if (!res_get(fh->dev,fh,RESOURCE_VBI)) @@ -876,22 +877,28 @@ video_poll(struct file *file, struct poll_table_struct *wait) return videobuf_poll_stream(file, &fh->vbiq, wait); } + mutex_lock(&fh->vidq.vb_lock); if (res_check(fh,RESOURCE_VIDEO)) { /* streaming capture */ if (list_empty(&fh->vidq.stream)) - return POLLERR; + goto err; buf = list_entry(fh->vidq.stream.next,struct cx88_buffer,vb.stream); } else { /* read() capture */ buf = (struct cx88_buffer*)fh->vidq.read_buf; if (NULL == buf) - return POLLERR; + goto err; } poll_wait(file, &buf->vb.done, wait); if (buf->vb.state == VIDEOBUF_DONE || buf->vb.state == VIDEOBUF_ERROR) - return POLLIN|POLLRDNORM; + rc = POLLIN|POLLRDNORM; + mutex_unlock(&fh->vidq.vb_lock); return 0; + +err: + mutex_unlock(&fh->vidq.vb_lock); + return POLLERR; } static int video_release(struct file *file)
bttv-driver.c,cx23885-video.c,cx88-video.c: poll method lose race condition for capture video. Signed-off-by: Figo.zhang <figo1802@gmail.com> --- drivers/media/video/bt8xx/bttv-driver.c | 7 +++++-- drivers/media/video/cx23885/cx23885-video.c | 15 +++++++++++---- drivers/media/video/cx88/cx88-video.c | 13 ++++++++++--- 3 files changed, 26 insertions(+), 9 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html