linux-kernel - [PATCH 3.16 098/136] route: update fnhe_expires for redirect when the fnhe exists

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Message-ID: <lsq.1518323471.458088158@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Hannes Frederic Sowa" <hannes@...essinduktion.org>,
        "Jianlin Shi" <jishi@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Xin Long" <lucien.xin@...il.com>
Subject: [PATCH 3.16 098/136] route: update fnhe_expires for redirect when
 the fnhe exists

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Xin Long <lucien.xin@...il.com>

commit e39d5246111399dbc6e11cd39fd8580191b86c47 upstream.

Now when creating fnhe for redirect, it sets fnhe_expires for this
new route cache. But when updating the exist one, it doesn't do it.
It will cause this fnhe never to be expired.

Paolo already noticed it before, in Jianlin's test case, it became
even worse:

When ip route flush cache, the old fnhe is not to be removed, but
only clean it's members. When redirect comes again, this fnhe will
be found and updated, but never be expired due to fnhe_expires not
being set.

So fix it by simply updating fnhe_expires even it's for redirect.

Fixes: aee06da6726d ("ipv4: use seqlock for nh_exceptions")
Reported-by: Jianlin Shi <jishi@...hat.com>
Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/ipv4/route.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -650,10 +650,9 @@ static void update_or_create_fnhe(struct
 	if (fnhe) {
 		if (gw)
 			fnhe->fnhe_gw = gw;
-		if (pmtu) {
+		if (pmtu)
 			fnhe->fnhe_pmtu = pmtu;
-			fnhe->fnhe_expires = max(1UL, expires);
-		}
+		fnhe->fnhe_expires = max(1UL, expires);
 		/* Update all cached dsts too */
 		rt = rcu_dereference(fnhe->fnhe_rth_input);
 		if (rt)