diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 096e2a37446d3e8fb333f45c342bc2a975607b34..7c8b15b22bf2e089fd9356debc9f967031723cbe 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -168,7 +168,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 	    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;