• Herbert Xu's avatar
    [TCP]: Adjust Reno SACK estimate in tcp_fragment · 83ca28be
    Herbert Xu authored
    Since the introduction of TSO pcount a year ago, it has been possible
    for tcp_fragment() to cause packets_out to decrease.  Prior to that,
    tcp_retrans_try_collapse() was the only way for that to happen on the
    retransmission path.
    
    When this happens with Reno, it is possible for sasked_out to become
    invalid because it is only an estimate and not tied to any particular
    packet on the retransmission queue.
    
    Therefore we need to adjust sacked_out as well as left_out in the Reno
    case.  The following patch does exactly that.
    
    This bug is pretty difficult to trigger in practice though since you
    need a SACKless peer with a retransmission that occurs just as the
    cached MTU value expires.
    Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    83ca28be
tcp_output.c 59.4 KB