From dc1d7df81146512cda3d56678e100be756116f60 Mon Sep 17 00:00:00 2001
From: itojun <itojun@NetBSD.org>
Date: Thu, 26 Jul 2001 05:47:37 +0000
Subject: [PATCH] do not initialize rmx_mtu on RTM_ADD.

on gateway change, copy rmx_mtu from gateway only under the following condition:
- current MTU is not locked
- current MTU was discovered via PMTUD

XXX if gateway has MTU == 0, current MTU is set to 0 and we are going to
rediscover PMTU again.  is it good or bad?
---
 sys/net/route.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/sys/net/route.c b/sys/net/route.c
index 0bfb45db42c2..1cd22a73e47d 100644
--- a/sys/net/route.c
+++ b/sys/net/route.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: route.c,v 1.46 2001/07/25 07:13:44 itojun Exp $	*/
+/*	$NetBSD: route.c,v 1.47 2001/07/26 05:47:37 itojun Exp $	*/
 
 /*-
  * Copyright (c) 1998 The NetBSD Foundation, Inc.
@@ -727,13 +727,15 @@ rt_setgate(rt0, dst, gate)
 		rt->rt_gwroute = rtalloc1(gate, 1);
 		/*
 		 * If we switched gateways, grab the MTU from the new
-		 * gateway route if the current MTU is 0 or greater
-		 * than the MTU of gateway.
+		 * gateway route if the current MTU, if the current MTU is
+		 * greater than the MTU of gateway.
+		 * Note that, if the MTU of gateway is 0, we will reset the
+		 * MTU of the route to run PMTUD again from scratch. XXX
 		 */
 		if (rt->rt_gwroute
 		    && !(rt->rt_rmx.rmx_locks & RTV_MTU)
-		    && (rt->rt_rmx.rmx_mtu == 0
-		    || rt->rt_rmx.rmx_mtu > rt->rt_gwroute->rt_rmx.rmx_mtu)) { /* XXX */
+		    && rt->rt_rmx.rmx_mtu
+		    && rt->rt_rmx.rmx_mtu > rt->rt_gwroute->rt_rmx.rmx_mtu) {
 			rt->rt_rmx.rmx_mtu = rt->rt_gwroute->rt_rmx.rmx_mtu;
 		}
 	}
@@ -821,7 +823,6 @@ rtinit(ifa, cmd, flags)
 			IFAFREE(rt->rt_ifa);
 			rt->rt_ifa = ifa;
 			rt->rt_ifp = ifa->ifa_ifp;
-			rt->rt_rmx.rmx_mtu = ifa->ifa_ifp->if_mtu;	/*XXX*/
 			IFAREF(ifa);
 			if (ifa->ifa_rtrequest)
 				ifa->ifa_rtrequest(RTM_ADD, rt, NULL);