netdev - [PATCH] ipv4: Fix flushing of cached routing informations

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Message-ID: <20121018052730.GB27385@secunet.com>
Date:	Thu, 18 Oct 2012 07:27:31 +0200
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: [PATCH] ipv4: Fix flushing of cached routing informations

Currently we can not flush cached pmtu/redirect informations via
the ipv4_sysctl_rtcache_flush sysctl. We need to check the rt_genid
of the old route and reset the nh exeption if the old route is
expired when we bind a new route to a nh exeption.

Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/ipv4/route.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 432f4bb..defb98d 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1163,8 +1163,17 @@ static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
 	spin_lock_bh(&fnhe_lock);
 
 	if (daddr == fnhe->fnhe_daddr) {
-		struct rtable *orig;
+		struct rtable *orig = rcu_dereference(fnhe->fnhe_rth);
+		rcu_assign_pointer(fnhe->fnhe_rth, rt);
 
+		if (orig) {
+			if (rt_is_expired(orig)) {
+				fnhe->fnhe_gw = 0;
+				fnhe->fnhe_pmtu = 0;
+				fnhe->fnhe_expires = 0;
+			}
+			rt_free(orig);
+		}
 		if (fnhe->fnhe_pmtu) {
 			unsigned long expires = fnhe->fnhe_expires;
 			unsigned long diff = expires - jiffies;
@@ -1181,11 +1190,6 @@ static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
 		} else if (!rt->rt_gateway)
 			rt->rt_gateway = daddr;
 
-		orig = rcu_dereference(fnhe->fnhe_rth);
-		rcu_assign_pointer(fnhe->fnhe_rth, rt);
-		if (orig)
-			rt_free(orig);
-
 		fnhe->fnhe_stamp = jiffies;
 		ret = true;
 	}
-- 
1.7.0.4

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