drm: check for minor master before allowing drop master.



When fast user switching a lot eventually we get to the point,
where we were checking for the wrong thing in this function.

Signed-off-by: Dave Airlie <airlied@redhat.com>

parent 6b008426

drivers/gpu/drm/drm_stub.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -185,6 +185,9 @@ int drm_dropmaster_ioctl(struct drm_device dev, void data,
		if (!file_priv->is_master)
		return -EINVAL;

		if (!file_priv->minor->master)
		return -EINVAL;

		mutex_lock(&dev->struct_mutex);
		drm_master_put(&file_priv->minor->master);
		file_priv->is_master = 0;