On Thu, Sep 14, 2017 at 12:32 PM, Yuchung Cheng <ych...@google.com> wrote: > On Thu, Sep 14, 2017 at 6:57 AM, Neal Cardwell <ncardw...@google.com> wrote: >> On Wed, Sep 13, 2017 at 11:30 PM, Eric Dumazet <eric.duma...@gmail.com> >> wrote: >>> >>> From: Eric Dumazet <eduma...@googl.com> >>> >>> liujian reported a problem in TCP_USER_TIMEOUT processing with a patch >>> in tcp_probe_timer() : >>> https://www.spinics.net/lists/netdev/msg454496.html >>> >>> After investigations, the root cause of the problem is that we update >>> skb->skb_mstamp of skbs in write queue, even if the attempt to send a >>> clone or copy of it failed. One reason being a routing problem. >>> >>> This patch prevents this, solving liujian issue. >>> >>> It also removes a potential RTT miscalculation, since >>> __tcp_retransmit_skb() is not OR-ing TCP_SKB_CB(skb)->sacked with >>> TCPCB_EVER_RETRANS if a failure happens, but skb->skb_mstamp has >>> been changed. >>> >>> A future ACK would then lead to a very small RTT sample and min_rtt >>> would then be lowered to this too small value. >> ... >>> >>> Signed-off-by: Eric Dumazet <eduma...@googl.com> >>> Reported-by: liujian <liujia...@huawei.com> >>> --- >>> net/ipv4/tcp_output.c | 19 ++++++++++++------- >>> 1 file changed, 12 insertions(+), 7 deletions(-) >> >> Acked-by: Neal Cardwell <ncardw...@google.com> > Acked-by: Yuchung Cheng <ych...@google.com>
Acked-by: Soheil Hassas Yeganeh <soh...@google.com> Very nice! Thank you, Eric!
