diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 096e2a3..7c8b15b 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -168,7 +168,7 @@
 	    file_priv->minor->master != file_priv->master) {
 		mutex_lock(&dev->struct_mutex);
 		file_priv->minor->master = drm_master_get(file_priv->master);
-		mutex_lock(&dev->struct_mutex);
+		mutex_unlock(&dev->struct_mutex);
 	}
 
 	return 0;