From owner-freebsd-net@FreeBSD.ORG  Sat Oct  2 21:01:33 2010
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id DCFDA106566C;
	Sat,  2 Oct 2010 21:01:33 +0000 (UTC)
	(envelope-from juli@clockworksquid.com)
Received: from mail-qw0-f54.google.com (mail-qw0-f54.google.com
	[209.85.216.54])
	by mx1.freebsd.org (Postfix) with ESMTP id 75F198FC0A;
	Sat,  2 Oct 2010 21:01:33 +0000 (UTC)
Received: by qwd6 with SMTP id 6so2701882qwd.13
	for <multiple recipients>; Sat, 02 Oct 2010 14:01:32 -0700 (PDT)
Received: by 10.224.45.135 with SMTP id e7mr5228880qaf.390.1286051777838; Sat,
	02 Oct 2010 13:36:17 -0700 (PDT)
MIME-Version: 1.0
Sender: juli@clockworksquid.com
Received: by 10.229.239.72 with HTTP; Sat, 2 Oct 2010 13:35:57 -0700 (PDT)
In-Reply-To: <9AD4923A-72AE-4FE3-A869-3AF8ECBF17E2@FreeBSD.org>
References: <4C9DA26D.7000309@freebsd.org>
	<AANLkTim7oRyVYY3frn7=cn4Et8Acbcq9cXja_bR6YWvP@mail.gmail.com>
	<4CA51024.8020307@freebsd.org>
	<alpine.BSF.2.00.1010021627230.49031@fledge.watson.org>
	<9AD4923A-72AE-4FE3-A869-3AF8ECBF17E2@FreeBSD.org>
From: Juli Mallett <jmallett@FreeBSD.org>
Date: Sat, 2 Oct 2010 13:35:57 -0700
X-Google-Sender-Auth: 7LqkUdxHoM_harpPhI0FxuvSfMk
Message-ID: <AANLkTi=uxARo5O9MASrx9mg-39E2=x05RXxcKUB62JrB@mail.gmail.com>
To: Rui Paulo <rpaulo@freebsd.org>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Cc: Ryan Stone <rysto32@gmail.com>, Robert Watson <rwatson@freebsd.org>,
	FreeBSD Net <net@freebsd.org>
Subject: Re: mbuf changes
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/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: Sat, 02 Oct 2010 21:01:33 -0000

On Sat, Oct 2, 2010 at 12:07, Rui Paulo <rpaulo@freebsd.org> wrote:
> On 2 Oct 2010, at 16:29, Robert Watson wrote:
>> On Thu, 30 Sep 2010, Julian Elischer wrote:
>>> On 9/30/10 10:49 AM, Ryan Stone wrote:
>>>> It's not a big thing but it would be nice to replace the m_next and m_=
nextpkt fields with queue.h macros.
>>> funny, I've never even thought of that..
>>
>> I have, and it's a massive change touching code all over the kernel in v=
ast quantities. =A0While in principle it's a good idea (consistently avoid =
hand-crafted linked lists), it's something I'd discourage on the basis that=
 it probably won't significant reduce the kernel bug count, but will make i=
t even harder for vendors with large local changes to the network stack to =
keep up.
>
> I think it could also increase the kernel bug count. Unfortunately, we ca=
n't do this incrementally.

Can't we?  What about a union, so that we can gradually convert things
but keep ABI and API compatibility?  I mean, as long as we use the
right queue.h type, anyway, it should be consistent?  STAILQ,
presumably.