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authorHans Verkuil <hverkuil@xs4all.nl>2010-09-26 08:47:38 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2010-10-21 01:06:14 -0200
commitee6869afc922a9849979e49bb3bbcad794872fcb (patch)
tree2266050d01da694d04b533a6509873888327108b /drivers/media/video/v4l2-event.c
parentc29fcff3daafbf46d64a543c1950bbd206ad8c1c (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.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index de74ce07b5e2..69fd343d4774 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);