ipv4: properly update pmtu
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@whatever-company.com> Signed-off-by: Eric Dumazet <edumazet@google.com> CC: Julian Anastasov <ja@ssi.bg> Tested-by: Sylvain Munaut <s.munaut@whatever-company.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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