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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: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hiroaki SHIMODA 2011-03-09 20:09:58 +00:00 committed by David S. Miller
parent bef55aebd5
commit 46af31800b
2 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
net/ipv4/inetpeer.c
View File

@ -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);

22
net/ipv4/route.c
View File

@ -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);
}
}