• Damian Lukowski's avatar
    Revert Backoff [v3]: Revert RTO on ICMP destination unreachable · f1ecd5d9
    Damian Lukowski authored
    Here, an ICMP host/network unreachable message, whose payload fits to
    TCP's SND.UNA, is taken as an indication that the RTO retransmission has
    not been lost due to congestion, but because of a route failure
    somewhere along the path.
    With true congestion, a router won't trigger such a message and the
    patched TCP will operate as standard TCP.
    
    This patch reverts one RTO backoff, if an ICMP host/network unreachable
    message, whose payload fits to TCP's SND.UNA, arrives.
    Based on the new RTO, the retransmission timer is reset to reflect the
    remaining time, or - if the revert clocked out the timer - a retransmission
    is sent out immediately.
    Backoffs are only reverted, if TCP is in RTO loss recovery, i.e. if
    there have been retransmissions and reversible backoffs, already.
    
    Changes from v2:
    1) Renaming of skb in tcp_v4_err() moved to another patch.
    2) Reintroduced tcp_bound_rto() and __tcp_set_rto().
    3) Fixed code comments.
    Signed-off-by: default avatarDamian Lukowski <damian@tvk.rwth-aachen.de>
    Acked-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    f1ecd5d9
tcp_timer.c 14.5 KB