From owner-freebsd-net@FreeBSD.ORG  Fri Nov  2 19:04:12 2012
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
 by hub.freebsd.org (Postfix) with ESMTP id 86110A89
 for <freebsd-net@freebsd.org>; Fri,  2 Nov 2012 19:04:12 +0000 (UTC)
 (envelope-from nitroboost@gmail.com)
Received: from mail-ee0-f54.google.com (mail-ee0-f54.google.com [74.125.83.54])
 by mx1.freebsd.org (Postfix) with ESMTP id 12E608FC0A
 for <freebsd-net@freebsd.org>; Fri,  2 Nov 2012 19:04:11 +0000 (UTC)
Received: by mail-ee0-f54.google.com with SMTP id c50so2528684eek.13
 for <freebsd-net@freebsd.org>; Fri, 02 Nov 2012 12:04:10 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
 h=mime-version:date:message-id:subject:from:to:content-type;
 bh=w5Dc8mIjkRF2ope0LKOFS0gGShoHoZW7Wd8fNtYXpM0=;
 b=lNHzVr6TwywMqFNeeV3azBcitA7AwtKJoAkTEP6TWKbngargBNtFzAud8JfSGaW72n
 WxftbwTwsxIZd7baIq8xwkc6aBp5FQQpVRCKK3bmpFrGMoDP6F17bEvqfkObixWpvotF
 BrS5UgJ10CHA7hgwEuwZxjMZSlXvbJvFfuAQy1VJL/Z+8k2pxjw7DqkJp3dSff2fdQsz
 Ar9CHsZQB7ObXwwhba0zPUkQnHxIKb2E0bzgtIsLhpDJfH/QtilJDDiiV0iUdIfgiRhX
 DRRa7RJtcoaaDOdIpWp6camPIV8ZzIIc3ot31eC3It2MVlGm6sunLoMz/M+Eaxb0zVKD
 Z0bA==
MIME-Version: 1.0
Received: by 10.14.182.5 with SMTP id n5mr9808367eem.5.1351883050759; Fri, 02
 Nov 2012 12:04:10 -0700 (PDT)
Received: by 10.14.218.133 with HTTP; Fri, 2 Nov 2012 12:04:10 -0700 (PDT)
Date: Fri, 2 Nov 2012 12:04:10 -0700
Message-ID: <CAAAm0r0xE+s_-K+HgC7pR7O_CweHv+e6KGxF96b3zTtXdpd7fQ@mail.gmail.com>
Subject: Session MTU update patch only 9
From: Jason Wolfe <nitroboost@gmail.com>
To: freebsd-net@freebsd.org
Content-Type: text/plain; charset=ISO-8859-1
X-Content-Filtered-By: Mailman/MimeDel 2.1.14
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 02 Nov 2012 19:04:12 -0000

Hi,

While attempting to fix a PMTUD bug in 8.3-RELEASE-p4 that appears to now
be resolved by r234342, I also came across r238516.  It appears this fix
only made it into 9/STABLE though, does anyone know why it wasn't brought
back to 8?  It's a fairly easy port, but I just wanted to confirm there
wasn't something else at play I'm missing.

  "If ip_output() returns EMSGSIZE to tcp_output(), then the latter calls
tcp_mtudisc(), which in its turn may call tcp_output(). Under certain
conditions (must admit they are very special) an infinite recursion can
happen.

To avoid recursion we can pass struct route to ip_output() and obtain
correct mtu. This allows us not to use tcp_mtudisc() but call
tcp_mss_update()
  directly."

Jason