Re: [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received

From: Eric Dumazet
Date: Fri Jan 31 2020 - 17:53:58 EST




On 1/31/20 2:11 PM, Neal Cardwell wrote:

> I looked into fixing this, but my quick reading of the Linux
> tcp_rcv_state_process() code is that it should behave correctly and
> that a connection in FIN_WAIT_1 that receives a FIN/ACK should move to
> TIME_WAIT.
>
> SeongJae, do you happen to have a tcpdump trace of the problematic
> sequence where the "process A" ends up in FIN_WAIT_2 when it should be
> in TIME_WAIT?
>
> If I have time I will try to construct a packetdrill case to verify
> the behavior in this case.

Unfortunately you wont be able to reproduce the issue with packetdrill,
since it involved packets being processed at the same time (race window)