From ee6869afc922a9849979e49bb3bbcad794872fcb Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sun, 26 Sep 2010 08:47:38 -0300 Subject: 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 Signed-off-by: Mauro Carvalho Chehab --- include/media/v4l2-dev.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/media/v4l2-dev.h') diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h index ba236ff35c8a..15802a067a12 100644 --- a/include/media/v4l2-dev.h +++ b/include/media/v4l2-dev.h @@ -94,6 +94,9 @@ struct video_device /* ioctl callbacks */ const struct v4l2_ioctl_ops *ioctl_ops; + + /* serialization lock */ + struct mutex *lock; }; /* dev to video-device */ -- cgit v1.2.3