Hi Hans, On Tuesday 23 November 2010 01:14:28 Hans Verkuil wrote: > On Monday, November 22, 2010 12:20:25 Hans Verkuil wrote: > > On Monday, November 22, 2010 11:21:27 Laurent Pinchart wrote: > > > Removing the mutex_lock/unlock around clear_bit allowed > > > device_unregister() to race with v4l2_open(). The device can be > > > unregistered between the video_devdata() and video_get() calls. > > > > > > Revert the patch to fix the problem. > > > > > > This reverts commit dd0daf2a6fb6bec436a3ef68bd585ea09a2a54b7. > > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > > > Acked-by: Hans Verkuil <hverkuil@xxxxxxxxx> > > Change of mind, I nack this. > > I realized that the mutex should be around device_unregister, not around > the clear_bit. The mutex protects access to vdev->dev and not vdev->flags > since that's atomic anyway. device_unregister() will end up calling v4l2_device_release(), which also locks videodev_lock. That will result in a deadlock. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
