diff options
| author | Hans Verkuil <hverkuil@xs4all.nl> | 2010-09-26 08:47:38 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2010-10-21 01:06:14 -0200 |
| commit | ee6869afc922a9849979e49bb3bbcad794872fcb (patch) | |
| tree | 2266050d01da694d04b533a6509873888327108b /drivers/media/video/v4l2-event.c | |
| parent | c29fcff3daafbf46d64a543c1950bbd206ad8c1c (diff) | |
V4L/DVB: v4l2: add core serialization lock
Drivers can optionally set a pointer to a mutex in struct video_device.
The core will use that to lock before calling open, read, write, unlocked_ioctl,
poll, mmap or release.
Updated the documentation as well and ensure that v4l2-event knows about the
lock: it will unlock it before doing a blocking wait on an event and relock it
afterwards.
Ensure that the 'video_is_registered' check is done when the lock is held:
a typical disconnect will take the lock as well before unregistering the
device nodes, so to prevent race conditions the video_is_registered check
should also be done with the lock held.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video/v4l2-event.c')
| -rw-r--r-- | drivers/media/video/v4l2-event.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c index de74ce07b5e..69fd343d477 100644 --- a/drivers/media/video/v4l2-event.c +++ b/drivers/media/video/v4l2-event.c @@ -134,15 +134,22 @@ int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event, if (nonblocking) return __v4l2_event_dequeue(fh, event); + /* Release the vdev lock while waiting */ + if (fh->vdev->lock) + mutex_unlock(fh->vdev->lock); + do { ret = wait_event_interruptible(events->wait, events->navailable != 0); if (ret < 0) - return ret; + break; ret = __v4l2_event_dequeue(fh, event); } while (ret == -ENOENT); + if (fh->vdev->lock) + mutex_lock(fh->vdev->lock); + return ret; } EXPORT_SYMBOL_GPL(v4l2_event_dequeue); |