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From 90f586dba1465a73295d752abe2451e924ba1888 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Mon, 27 May 2013 08:33:10 +0300
Subject: [PATCH 4/6] ipv4: rate limit updating of next hop exceptions with
same pmtu
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
The tunnel devices call update_pmtu for each packet sent, this causes
contention on the fnhe_lock. Ignore the pmtu update if pmtu is not
actually changed, and there is still plenty of time before the entry
expires.
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
---
net/ipv4/route.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 8dedfeb..85b9c07 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -947,6 +947,10 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
if (mtu < ip_rt_min_pmtu)
mtu = ip_rt_min_pmtu;
+ if (rt->rt_pmtu == mtu &&
+ time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
+ return;
+
rcu_read_lock();
if (fib_lookup(dev_net(dst->dev), fl4, &res) == 0) {
struct fib_nh *nh = &FIB_RES_NH(res);
--
1.8.2.3
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