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ipv4: Fix route refcount on pmtu discovery 

git commit 9cb3a50c (ipv4: Invalidate the socket cached route on
pmtu events if possible) introduced a refcount problem. We don't
get a refcount on the route if we get it from__sk_dst_get(), but
we need one if we want to reuse this route because __sk_dst_set()
releases the refcount of the old route. This patch adds proper
refcount handling for that case. We introduce a 'new' flag to
indicate that we are going to use a new route and we release the
old route only if we replace it by a new one.

Reported-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Steffen Klassert 2013-01-22 00:01:28 +00:00 committed by David S. Miller
parent 0c8729c9b9
commit b44108dbdb
1 changed files with 9 additions and 2 deletions
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11
net/ipv4/route.c
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@ -985,6 +985,7 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
struct flowi4 fl4;
struct rtable *rt;
struct dst_entry *dst;
bool new = false;
bh_lock_sock(sk);
rt = (struct rtable *) __sk_dst_get(sk);
@ -1000,20 +1001,26 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
if (IS_ERR(rt))
goto out;
new = true;
}
__ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
dst = dst_check(&rt->dst, 0);
if (!dst) {
if (new)
dst_release(&rt->dst);
rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
if (IS_ERR(rt))
goto out;
dst = &rt->dst;
new = true;
}
__sk_dst_set(sk, dst);
if (new)
__sk_dst_set(sk, &rt->dst);
out:
bh_unlock_sock(sk);