From: David Laight <David.Laight@ACULAB.COM>
To: 'Eric Dumazet' <eric.dumazet@gmail.com>,
Neal Cardwell <ncardwell@google.com>
Cc: "sjpark@amazon.com" <sjpark@amazon.com>,
Eric Dumazet <edumazet@google.com>,
David Miller <davem@davemloft.net>,
"shuah@kernel.org" <shuah@kernel.org>,
Netdev <netdev@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"sj38.park@gmail.com" <sj38.park@gmail.com>,
"aams@amazon.com" <aams@amazon.com>,
SeongJae Park <sjpark@amazon.de>,
Yuchung Cheng <ycheng@google.com>
Subject: RE: [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received
Date: Mon, 3 Feb 2020 15:40:04 +0000 [thread overview]
Message-ID: <5a8c1658de8f49b2994d19d371c13c79@AcuMS.aculab.com> (raw)
In-Reply-To: <7d36a817-5519-8496-17cf-00eda5ed4ec7@gmail.com>
From: Eric Dumazet
> Sent: 31 January 2020 22:54
> 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)
You might be able to force the timing race by adding a sleep
in one of the code paths.
No good for a regression test, but ok for code testing.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-02-03 15:40 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
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 [this message]
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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