Commit 46af3180 authored by Hiroaki SHIMODA's avatar Hiroaki SHIMODA Committed by David S. Miller
Browse files

ipv4: Fix PMTU update. 



On current net-next-2.6, when Linux receives ICMP Type: 3, Code: 4
(Destination unreachable (Fragmentation needed)),

  icmp_unreach
    -> ip_rt_frag_needed
         (peer->pmtu_expires is set here)
    -> tcp_v4_err
         -> do_pmtu_discovery
              -> ip_rt_update_pmtu
                   (peer->pmtu_expires is already set,
                    so check_peer_pmtu is skipped.)
                   -> check_peer_pmtu

check_peer_pmtu is skipped and MTU is not updated.

To fix this, let check_peer_pmtu execute unconditionally.
And some minor fixes
1) Avoid potential peer->pmtu_expires set to be zero.
2) In check_peer_pmtu, argument of time_before is reversed.
3) check_peer_pmtu expects peer->pmtu_orig is initialized as zero,
   but not initialized.

Signed-off-by: default avatarHiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bef55aeb

net/ipv4/inetpeer.c

+1 −0
Original line number Diff line number Diff line
@@ -511,6 +511,7 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) 
		p->rate_tokens = 0;

		p->rate_last = 0;

		p->pmtu_expires = 0;

		p->pmtu_orig = 0;

		memset(&p->redirect_learned, 0, sizeof(p->redirect_learned));

		INIT_LIST_HEAD(&p->unused);

net/ipv4/route.c

+17 −5
Original line number Diff line number Diff line
@@ -1533,9 +1533,15 @@ unsigned short ip_rt_frag_needed(struct net *net, struct iphdr *iph, 
		if (mtu < ip_rt_min_pmtu)

			mtu = ip_rt_min_pmtu;

		if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {

			unsigned long pmtu_expires;



			pmtu_expires = jiffies + ip_rt_mtu_expires;

			if (!pmtu_expires)

				pmtu_expires = 1UL;



			est_mtu = mtu;

			peer->pmtu_learned = mtu;

			peer->pmtu_expires = jiffies + ip_rt_mtu_expires;

			peer->pmtu_expires = pmtu_expires;

		}



		inet_putpeer(peer);
@@ -1549,7 +1555,7 @@ static void check_peer_pmtu(struct dst_entry *dst, struct inet_peer *peer) 
{

	unsigned long expires = peer->pmtu_expires;



	if (time_before(expires, jiffies)) {

	if (time_before(jiffies, expires)) {

		u32 orig_dst_mtu = dst_mtu(dst);

		if (peer->pmtu_learned < orig_dst_mtu) {

			if (!peer->pmtu_orig)
@@ -1574,14 +1580,20 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu) 
		if (mtu < ip_rt_min_pmtu)

			mtu = ip_rt_min_pmtu;

		if (!peer->pmtu_expires || mtu < peer->pmtu_learned) {

			unsigned long pmtu_expires;



			pmtu_expires = jiffies + ip_rt_mtu_expires;

			if (!pmtu_expires)

				pmtu_expires = 1UL;



			peer->pmtu_learned = mtu;

			peer->pmtu_expires = jiffies + ip_rt_mtu_expires;

			peer->pmtu_expires = pmtu_expires;



			atomic_inc(&__rt_peer_genid);

			rt->rt_peer_genid = rt_peer_genid();



			check_peer_pmtu(dst, peer);

		}

		check_peer_pmtu(dst, peer);



		inet_putpeer(peer);

	}

}

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