From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [BUG] tcp : how many times a frame can possibly be
 retransmitted ?
Date: Wed, 24 Aug 2011 21:45:32 +0200
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Cc: netdev <netdev@vger.kernel.org>, Jerry Chu <hkchu@google.com>,
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	Hannemann Arnd <arnd@arndnet.de>
To: Alexander Zimmermann <alexander.zimmermann@comsys.rwth-aachen.de>
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Le mercredi 24 ao=C3=BBt 2011 =C3=A0 21:03 +0200, Alexander Zimmermann =
a =C3=A9crit :
> Hi Eric,
>=20
> Am 24.08.2011 um 18:21 schrieb Eric Dumazet:
>=20
> > On one dev machine running net-next, I just found strange tcp sessi=
ons
> > that retransmit a frame forever (The other peer disappeared)
>=20
> not forever...
> If remember correctly you will stop after 120s.
>=20

Hi Alexander

I just tried again one session, and got much more delay than that.

It stops because of a side effect, "icsk_retransmits" being a 8bit
field.

Every 256 retransmits, it becomes 255+1 -> 0

retransmits_timed_out() immediately returns false.

And backoff increases at this time.

Eventually, we retransmit 256*15 times, process 256*15 ICMP messages.

Thanks