v4.19.13 snapshot.
diff --git a/lib/locking-selftest-rtmutex.h b/lib/locking-selftest-rtmutex.h
new file mode 100644
index 0000000..fce8714
--- /dev/null
+++ b/lib/locking-selftest-rtmutex.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef LOCK
+#define LOCK		RTL
+
+#undef UNLOCK
+#define UNLOCK		RTU
+
+#undef RLOCK
+#undef WLOCK
+
+#undef INIT
+#define INIT		RTI