netdev - [PATCH V2] ipv6: Fix problem with expired dst cache

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Date:	Mon, 27 Feb 2012 14:36:45 +0800
From:	Gao feng <gaofeng@...fujitsu.com>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, eric.dumazet@...il.com,
	Gao feng <gaofeng@...fujitsu.com>
Subject: [PATCH V2] ipv6: Fix problem with expired dst cache

If the ipv6 dst cache which copy from the dst generated by ICMPV6 RA packet.
this dst cache will not check expire because it has no RTF_EXPIRES flag.
So this dst cache will always be used until the dst gc run.

Change the struct dst_entry,add a union contains new pointer from and expires.
When rt6_info.rt6i_flags has no RTF_EXPIRES flag,the dst.expires has no use.
we can use this field to point to where the dst cache copy from.
The dst.from is only used in IPV6.

In func rt6_check_expired check if rt6_info.dst.from is expired.

In func ip6_rt_copy only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.

Signed-off-by: Gao feng <gaofeng@...fujitsu.com>
---
 include/net/dst.h |   11 ++++++++++-
 net/ipv6/route.c  |   22 +++++++++++++++++++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/include/net/dst.h b/include/net/dst.h
index 344c8dd..eae92f9 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -35,7 +35,16 @@ struct dst_entry {
 	struct net_device       *dev;
 	struct  dst_ops	        *ops;
 	unsigned long		_metrics;
-	unsigned long		expires;
+
+	union {
+		unsigned long		expires;
+		/*
+		 *from is used only for dst cache witch copy form
+		 *the dst generated by ipv6 RA.
+		 */
+		void			*from;
+	};
+
 	struct dst_entry	*path;
 	struct neighbour __rcu	*_neighbour;
 #ifdef CONFIG_XFRM
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 8c2e3ab..cd365fe 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -316,8 +316,18 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
 
 static __inline__ int rt6_check_expired(const struct rt6_info *rt)
 {
-	return (rt->rt6i_flags & RTF_EXPIRES) &&
-		time_after(jiffies, rt->dst.expires);
+	struct rt6_info *ort = NULL;
+
+	if (rt->rt6i_flags & RTF_EXPIRES) {
+		if (time_after(jiffies, rt->dst.expires))
+			return 1;
+	} else if (rt->dst.from) {
+		ort = (struct rt6_info *) rt->dst.from;
+		return (ort->rt6i_flags & RTF_EXPIRES) &&
+			time_after(jiffies, ort->dst.expires);
+	}
+
+	return 0;
 }
 
 static inline int rt6_need_strict(const struct in6_addr *daddr)
@@ -608,6 +618,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
 
 	if (rt) {
 		if (!addrconf_finite_timeout(lifetime)) {
+			rt->dst.expires = 0;
 			rt->rt6i_flags &= ~RTF_EXPIRES;
 		} else {
 			rt->dst.expires = jiffies + HZ * lifetime;
@@ -1799,7 +1810,12 @@ static struct rt6_info *ip6_rt_copy(const struct rt6_info *ort,
 		if (rt->rt6i_idev)
 			in6_dev_hold(rt->rt6i_idev);
 		rt->dst.lastuse = jiffies;
-		rt->dst.expires = 0;
+
+		if ((ort->rt6i_flags & (RTF_ADDRCONF | RTF_DEFAULT)) ==
+		    (RTF_ADDRCONF | RTF_DEFAULT))
+			rt->dst.from = (void *)ort;
+		else
+			rt->dst.expires = 0;
 
 		rt->rt6i_gateway = ort->rt6i_gateway;
 		rt->rt6i_flags = ort->rt6i_flags & ~RTF_EXPIRES;
-- 
1.7.5.4

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