From: Stephen Hemminger <stephen@networkplumber.org>
To: netdev@vger.kernel.org
Subject: Fw: [Bug 194723] connect() to localhost stalls after 4.9 -> 4.10 upgrade
Date: Thu, 2 Mar 2017 10:32:49 -0800 [thread overview]
Message-ID: <20170302103249.671ef5a5@xeon-e3> (raw)
Begin forwarded message:
Date: Wed, 01 Mar 2017 12:04:45 +0000
From: bugzilla-daemon@bugzilla.kernel.org
To: stephen@networkplumber.org
Subject: [Bug 194723] connect() to localhost stalls after 4.9 -> 4.10 upgrade
https://bugzilla.kernel.org/show_bug.cgi?id=194723
--- Comment #2 from Lutz Vieweg (lvml@5t9.de) ---
Using tcpdump I found that when the connect() stalls, the initial SYN packet
appears at the "lo" interface, and is re-sent multiple times, but no ACK packet
is ever returned.
Error case with linux-4.10:
> 12:57:25.685640 IP 127.0.0.1.44074 > 127.0.0.1.dnp-sec: Flags [S], seq
> 1952288470, win 43690, options [mss 65495,sackOK,TS val 1942998659 ecr
> 0,nop,wscale 7], length 0
> 12:57:26.728890 IP 127.0.0.1.44074 > 127.0.0.1.dnp-sec: Flags [S], seq
> 1952288470, win 43690, options [mss 65495,sackOK,TS val 1942999703 ecr
> 0,nop,wscale 7], length 0
> 12:57:28.776935 IP 127.0.0.1.44074 > 127.0.0.1.dnp-sec: Flags [S], seq
> 1952288470, win 43690, options [mss 65495,sackOK,TS val 1943001751 ecr
> 0,nop,wscale 7], length 0
...
Normal case:
> 13:01:43.037135 IP 127.0.0.1.44362 > 127.0.0.1.dnp-sec: Flags [S], seq
> 3181010757, win 43690, options [mss 65495,sackOK,TS val 3314900273 ecr
> 0,nop,wscale 7], length 0
> 13:01:43.037171 IP 127.0.0.1.dnp-sec > 127.0.0.1.44362: Flags [S.], seq
> 1934682061, ack 3181010758, win 43690, options [mss 65495,sackOK,TS val
> 2947413993 ecr 3314900273,nop,wscale 7], length 0
> 13:01:43.037196 IP 127.0.0.1.44362 > 127.0.0.1.dnp-sec: Flags [.], ack 1, win
> 342, options [nop,nop,TS val 3314900273 ecr 2947413993], length 0
According to strace, the listening process does not even leave the select()
call it uses to wait for incoming connections to accept in the error case.
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next reply other threads:[~2017-03-02 18:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-02 18:32 Stephen Hemminger [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-03-15 20:36 Fw: [Bug 194723] connect() to localhost stalls after 4.9 -> 4.10 upgrade Stephen Hemminger
2017-03-15 21:40 ` Eric Dumazet
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