Subject: [PATCH 2/6] route: Use ipv4_mtu instead of raw rt_pmtu

From: Herbert Xu <[email-masked]>
Date: Tue, 28 Apr 2015 11:43:15 +0800

[ Upstream commit cb6ccf09d6b94bec4def1ac5cf4678d12b216474 ]

The commit 3cdaa5be9e81a914e633a6be7b7d2ef75b528562 ("ipv4: Don't
increase PMTU with Datagram Too Big message") broke PMTU in cases
where the rt_pmtu value has expired but is smaller than the new
PMTU value.

This obsolete rt_pmtu then prevents the new PMTU value from being
installed.

Fixes: 3cdaa5be9e81 ("ipv4: Don't increase PMTU with Datagram Too Big message")
Reported-by: Gerd v. Egidy <[email-masked]>
Signed-off-by: Herbert Xu <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv4/route.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ad50643..20fc020 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -963,10 +963,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 	if (dst_metric_locked(dst, RTAX_MTU))
 		return;
 
-	if (dst->dev->mtu < mtu)
-		return;
-
-	if (rt->rt_pmtu && rt->rt_pmtu < mtu)
+	if (ipv4_mtu(dst) < mtu)
 		return;
 
 	if (mtu < ip_rt_min_pmtu)
-- 
2.3.6