From: SeongJae Park <sj38.park@gmail.com>
To: Neal Cardwell <ncardwell@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
sjpark@amazon.com, Eric Dumazet <edumazet@google.com>,
David Miller <davem@davemloft.net>,
shuah@kernel.org, Netdev <netdev@vger.kernel.org>,
linux-kselftest@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
sj38.park@gmail.com, aams@amazon.com,
SeongJae Park <sjpark@amazon.de>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: Re: [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received
Date: Fri, 31 Jan 2020 23:17:55 +0100 [thread overview]
Message-ID: <20200131221755.3874-1-sj38.park@gmail.com> (raw)
In-Reply-To: <CADVnQy=Z0YRPY_0bxBpsZvECgamigESNKx6_-meNW5-6_N4kww@mail.gmail.com> (raw)
On Fri, 31 Jan 2020 17:11:35 -0500 Neal Cardwell <ncardwell@google.com> wrote:
> On Fri, Jan 31, 2020 at 1:12 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >
> >
> >
> > On 1/31/20 7:10 AM, Neal Cardwell wrote:
> > > On Fri, Jan 31, 2020 at 7:25 AM <sjpark@amazon.com> wrote:
> > >>
> > >> From: SeongJae Park <sjpark@amazon.de>
> > >>
> > >> When closing a connection, the two acks that required to change closing
> > >> socket's status to FIN_WAIT_2 and then TIME_WAIT could be processed in
> > >> reverse order. This is possible in RSS disabled environments such as a
> > >> connection inside a host.
[...]
>
> 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?
Hi Neal,
Yes, I have. You can get it from the previous discussion for this patchset
(https://lore.kernel.org/bpf/20200129171403.3926-1-sjpark@amazon.com/). As it
also has a reproducer program and how I got the tcpdump trace, I believe you
could get your own trace, too. If you have any question or need help, feel
free to let me know. :)
Thanks,
SeongJae Park
>
> If I have time I will try to construct a packetdrill case to verify
> the behavior in this case.
>
> thanks,
> neal
>
> >
next prev parent reply other threads:[~2020-01-31 22:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 12:24 [PATCH 0/3] Fix reconnection latency caused by FIN/ACK handling race sjpark
2020-01-31 12:24 ` [PATCH 1/3] net/ipv4/inet_timewait_sock: Fix inconsistent comments sjpark
2020-01-31 14:54 ` Eric Dumazet
2020-01-31 15:09 ` sjpark
2020-01-31 12:24 ` [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received sjpark
2020-01-31 15:01 ` Eric Dumazet
2020-01-31 16:12 ` sjpark
2020-01-31 16:55 ` Eric Dumazet
2020-01-31 17:05 ` sjpark
2020-01-31 17:08 ` Eric Dumazet
2020-01-31 15:10 ` Neal Cardwell
2020-01-31 18:12 ` Eric Dumazet
2020-01-31 22:11 ` Neal Cardwell
2020-01-31 22:17 ` SeongJae Park [this message]
2020-02-01 3:55 ` Neal Cardwell
2020-02-01 6:08 ` SeongJae Park
2020-02-01 13:30 ` Neal Cardwell
2020-01-31 22:53 ` Eric Dumazet
2020-02-03 15:40 ` David Laight
2020-02-03 15:54 ` Eric Dumazet
2020-01-31 12:24 ` [PATCH 3/3] selftests: net: Add FIN_ACK processing order related latency spike test sjpark
2020-01-31 14:56 ` Eric Dumazet
2020-01-31 15:13 ` sjpark
2020-01-31 14:00 ` [PATCH 0/3] Fix reconnection latency caused by FIN/ACK handling race David Laight
2020-01-31 15:05 ` sjpark
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