--- //depot/vendor/freebsd/src/sys/kern/kern_timeout.c	2007/11/20 00:42:27
+++ //depot/user/attilio/attilio_schedlock/kern/kern_timeout.c	2007/11/21 01:14:44
@@ -293,7 +293,8 @@
 					lastfunc = c_func;
 				}
 #endif
-				if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
+				if (class != NULL &&
+				    (c_flags & CALLOUT_RETURNUNLOCKED) == 0)
 					class->lc_unlock(c->c_lock);
 			skip:
 				mtx_lock_spin(&callout_lock);