* [PATCH] bttv-driver.c :poll method lose race condition for capture video
@ 2009-05-31 6:32 Figo.zhang
2009-05-31 21:29 ` Trent Piepho
0 siblings, 1 reply; 2+ messages in thread
From: Figo.zhang @ 2009-05-31 6:32 UTC (permalink / raw)
To: Mauro Carvalho Chehab
Cc: linux-media, kraxel, Hans Verkuil, Oldřich Jedlička
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(-)
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)
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] bttv-driver.c :poll method lose race condition for capture video
2009-05-31 6:32 [PATCH] bttv-driver.c :poll method lose race condition for capture video Figo.zhang
@ 2009-05-31 21:29 ` Trent Piepho
0 siblings, 0 replies; 2+ messages in thread
From: Trent Piepho @ 2009-05-31 21:29 UTC (permalink / raw)
To: Figo.zhang
Cc: Mauro Carvalho Chehab, linux-media, kraxel, Hans Verkuil,
Oldřich Jedlička
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;
}
^ permalink raw reply [flat|nested] 2+ messages in thread
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2009-05-31 21:29 ` Trent Piepho
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