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. Regards, Hans > > > --- > > drivers/media/video/v4l2-dev.c | 2 ++ > > 1 files changed, 2 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c > > index 03f7f46..f777da6 100644 > > --- a/drivers/media/video/v4l2-dev.c > > +++ b/drivers/media/video/v4l2-dev.c > > @@ -596,7 +596,9 @@ void video_unregister_device(struct video_device *vdev) > > if (!vdev || !video_is_registered(vdev)) > > return; > > > > + mutex_lock(&videodev_lock); > > clear_bit(V4L2_FL_REGISTERED, &vdev->flags); > > + mutex_unlock(&videodev_lock); > > device_unregister(&vdev->dev); > > } > > EXPORT_SYMBOL(video_unregister_device); > > > > -- Hans Verkuil - video4linux developer - sponsored by Cisco -- 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
