Index: sys/kern/kern_timeout.c
===================================================================
--- sys/kern/kern_timeout.c
+++ sys/kern/kern_timeout.c
@@ -1096,6 +1096,11 @@
 	struct lock_class *class;
 	int direct, sq_locked, use_lock;
 
+	if (safe) {
+		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
+		    "calling %s", __func__);
+	}
+
 	/*
 	 * Some old subsystems don't hold Giant while running a callout_stop(),
 	 * so just discard this check for the moment.