netdev - [PATCH] ipv6: fix rt6_update

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Message-ID: <20120416133439.GB18159@midget.suse.cz>
Date:	Mon, 16 Apr 2012 15:34:39 +0200
From:	Jiri Bohac <jbohac@...e.cz>
To:	David Miller <davem@...emloft.net>
Cc:	gaofeng@...fujitsu.com, netdev@...r.kernel.org
Subject: [PATCH] ipv6: fix rt6_update_expires


Commit 1716a961 (ipv6: fix problem with expired dst cache) broke PMTU
discovery. rt6_update_expires() calls dst_set_expires(), which only updates
dst->expires if it has not been set previously (expires == 0) or if the new
expires is earlier than the current dst->expires.

rt6_update_expires() needs to zero rt->dst.expires, otherwise it will contain
ivalid data left over from rt->dst.from and will confuse dst_set_expires().

Signed-off-by: Jiri Bohac <jbohac@...e.cz>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index ad4126f..68c1f94 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -143,8 +143,13 @@ static inline void rt6_set_expires(struct rt6_info *rt, unsigned long expires)
 
 static inline void rt6_update_expires(struct rt6_info *rt, int timeout)
 {
-	if (!(rt->rt6i_flags & RTF_EXPIRES) && rt->dst.from)
-		dst_release(rt->dst.from);
+	if (!(rt->rt6i_flags & RTF_EXPIRES)) {
+		if (rt->dst.from)
+			dst_release(rt->dst.from);
+		/* dst_set_expires relies on expires == 0 
+                  if it has not been set previously */
+		rt->dst.expires = 0;
+	}
 
 	dst_set_expires(&rt->dst, timeout);
 	rt->rt6i_flags |= RTF_EXPIRES;

-- 
Jiri Bohac <jbohac@...e.cz>
SUSE Labs, SUSE CZ

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