linux-kernel - [PATCH 3.16 099/136] route: also update fnhe

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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, "David S. Miller" <davem@...emloft.net>,
        "Xin Long" <lucien.xin@...il.com>,
        "Hannes Frederic Sowa" <hannes@...essinduktion.org>
Subject: [PATCH 3.16 099/136] route: also update fnhe_genid when updating
 a route cache

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

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

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

commit cebe84c6190d741045a322f5343f717139993c08 upstream.

Now when ip route flush cache and it turn out all fnhe_genid != genid.
If a redirect/pmtu icmp packet comes and the old fnhe is found and all
it's members but fnhe_genid will be updated.

Then next time when it looks up route and tries to rebind this fnhe to
the new dst, the fnhe will be flushed due to fnhe_genid != genid. It
causes this redirect/pmtu icmp packet acutally not to be applied.

This patch is to also reset fnhe_genid when updating a route cache.

Fixes: 5aad1de5ea2c ("ipv4: use separate genid for next hop exceptions")
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 | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -623,9 +623,12 @@ static void update_or_create_fnhe(struct
 	struct fnhe_hash_bucket *hash;
 	struct fib_nh_exception *fnhe;
 	struct rtable *rt;
+	u32 genid, hval;
 	unsigned int i;
 	int depth;
-	u32 hval = fnhe_hashfun(daddr);
+
+	genid = fnhe_genid(dev_net(nh->nh_dev));
+	hval = fnhe_hashfun(daddr);
 
 	spin_lock_bh(&fnhe_lock);
 
@@ -648,6 +651,8 @@ static void update_or_create_fnhe(struct
 	}
 
 	if (fnhe) {
+		if (fnhe->fnhe_genid != genid)
+			fnhe->fnhe_genid = genid;
 		if (gw)
 			fnhe->fnhe_gw = gw;
 		if (pmtu)
@@ -671,7 +676,7 @@ static void update_or_create_fnhe(struct
 			fnhe->fnhe_next = hash->chain;
 			rcu_assign_pointer(hash->chain, fnhe);
 		}
-		fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
+		fnhe->fnhe_genid = genid;
 		fnhe->fnhe_daddr = daddr;
 		fnhe->fnhe_gw = gw;
 		fnhe->fnhe_pmtu = pmtu;