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From: Bill Fink <billfink@mindspring.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Ilpo Järvinen " <ilpo.jarvinen@helsinki.fi>,
	"Guillaume Chazarain" <guichaz@gmail.com>,
	"Giangiacomo Mariotti" <giangiacomo_mariotti@yahoo.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Netdev <netdev@vger.kernel.org>
Subject: Re: WARNING: at net/ipv4/tcp_input.c:2054 tcp_mark_head_lost()
Date: Thu, 28 Feb 2008 23:35:14 -0500	[thread overview]
Message-ID: <20080228233514.63b7136e.billfink@mindspring.com> (raw)
In-Reply-To: <20080228171011.fc56eace.akpm@linux-foundation.org>

On Thu, 28 Feb 2008, Andrew Morton wrote:

> On Thu, 28 Feb 2008 10:22:27 +0200 (EET) "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote:
> 
> > [PATCH] TCP debug S+L (for 2.6.25-rcs, incompatible with 2.6.24.y)
> > 
> > ---
> >  include/net/tcp.h     |    9 +++-
> >  net/ipv4/tcp_input.c  |   18 +++++++-
> >  net/ipv4/tcp_ipv4.c   |  127 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  net/ipv4/tcp_output.c |   23 +++++++--
> 
> I'll put this in -mm, see if we can flush anything out.  Please let me know
> if/when it's obsolete, updated, etc.
> 
> What is "S+L"?

I'll let Ilpo give the definitive answer.  But to test if I'm starting
to grasp this, I'll give my understanding.  I believe 'S' means that a
transmitted TCP skb has been acknowledged by a SACK, while 'L' means
that a transmitted SKB is believed lost.  Since the 'S' state implies
that the packet has actually been successfully received, it should not be
possible for it to be considered lost ('L' state).  Thus an "S+L" state
for a TCP skb is an internally inconsistent state and an indication of
a TCP bug.

Anyone feel free to correct me if I'm way off base in my understanding.

						-Bill

  reply	other threads:[~2008-02-29  4:35 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-21  4:04 Giangiacomo Mariotti
2008-02-23  8:03 ` Andrew Morton
2008-02-27  9:29   ` Ilpo Järvinen
2008-02-27 18:56     ` Guillaume Chazarain
2008-02-27 19:29       ` Ilpo Järvinen
2008-02-28  8:22         ` Ilpo Järvinen
2008-02-29  1:10           ` Andrew Morton
2008-02-29  4:35             ` Bill Fink [this message]
2008-02-29 12:24               ` Ilpo Järvinen
2008-03-02 12:20           ` Guillaume Chazarain
2008-03-02 12:38             ` Ilpo Järvinen
2008-03-02 13:15               ` Guillaume Chazarain
2008-03-02 19:51                 ` Ilpo Järvinen
2008-03-03  8:32                   ` Ilpo Järvinen
2008-03-03 13:40                     ` Ilpo Järvinen
2008-03-03 13:53                       ` [PATCH net-2.6] [TCP]: Must count fack_count also when skipping Ilpo Järvinen
2008-03-03 20:11                         ` David Miller
2008-03-24 20:36                         ` Frederik Himpe
2008-03-24 21:41                           ` David Miller
2008-03-25 21:24                             ` Ilpo Järvinen
2008-03-26  3:05                               ` David Miller

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