--- route.h.orig	Tue Apr  4 22:07:23 2006
+++ route.h	Mon Dec 17 13:11:44 2007
@@ -289,6 +289,7 @@
 #define	RT_LOCK_INIT(_rt) \
 	mtx_init(&(_rt)->rt_mtx, "rtentry", NULL, MTX_DEF | MTX_DUPOK)
 #define	RT_LOCK(_rt)		mtx_lock(&(_rt)->rt_mtx)
+#define	RT_TRYLOCK(_rt)		mtx_trylock(&(_rt)->rt_mtx)
 #define	RT_UNLOCK(_rt)		mtx_unlock(&(_rt)->rt_mtx)
 #define	RT_LOCK_DESTROY(_rt)	mtx_destroy(&(_rt)->rt_mtx)
 #define	RT_LOCK_ASSERT(_rt)	mtx_assert(&(_rt)->rt_mtx, MA_OWNED)
--- route.c.orig	Tue Oct 30 19:07:54 2007
+++ route.c	Mon Dec 17 15:13:20 2007
@@ -996,6 +996,7 @@
 	struct radix_node_head *rnh = rt_tables[dst->sa_family];
 	int dlen = SA_SIZE(dst), glen = SA_SIZE(gate);
 
+again:
 	RT_LOCK_ASSERT(rt);
 
 	/*
@@ -1029,7 +1030,15 @@
 			RT_REMREF(rt);
 			return (EADDRINUSE); /* failure */
 		}
-		RT_LOCK(rt);
+		/*
+		 * Try to reacquire the lock on rt, and if it fails,
+		 * clean state and restart from scratch.
+		 */
+		if (!RT_TRYLOCK(rt)) {
+			RTFREE_LOCKED(gwrt);
+			RT_LOCK(rt);
+			goto again;
+		}
 		/*
 		 * If there is already a gwroute, then drop it. If we
 		 * are asked to replace route with itself, then do