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Date: Wed, 22 Aug 2012 08:48:29 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: David Miller <davem@...emloft.net> Cc: netdev <netdev@...r.kernel.org>, Julian Anastasov <ja@....bg>, Sylvain Munaut <s.munaut@...tever-company.com> Subject: [PATCH] ipv4: properly update pmtu From: Eric Dumazet <edumazet@...gle.com> Sylvain Munault reported following info : - TCP connection get "stuck" with data in send queue when doing "large" transfers ( like typing 'ps ax' on a ssh connection ) - Only happens on path where the PMTU is lower than the MTU of the interface - Is not present right after boot, it only appears 10-20min after boot or so. (and that's inside the _same_ TCP connection, it works fine at first and then in the same ssh session, it'll get stuck) - Definitely seems related to fragments somehow since I see a router sending ICMP message saying fragmentation is needed. - Exact same setup works fine with kernel 3.5.1 Problem happens when the 10 minutes (ip_rt_mtu_expires) expiration period is over. ip_rt_update_pmtu() calls dst_set_expires() to rearm a new expiration, but dst_set_expires() does nothing because dst.expires is already set. It seems we want to set the expires field to a new value, regardless of prior one. With help from Julian Anastasov. Reported-by: Sylvain Munaut <s.munaut@...tever-company.com> Signed-off-by: Eric Dumazet <edumazet@...gle.com> CC: Julian Anastasov <ja@....bg> --- net/ipv4/route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index e4ba974..8d6d320 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -956,7 +956,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, dst->obsolete = DST_OBSOLETE_KILL; } else { rt->rt_pmtu = mtu; - dst_set_expires(&rt->dst, ip_rt_mtu_expires); + rt->dst.expires = max(1UL, jiffies + ip_rt_mtu_expires); } } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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