From owner-freebsd-net@FreeBSD.ORG  Thu Jun 12 16:38:01 2008
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 57BB61065672
	for <freebsd-net@freebsd.org>; Thu, 12 Jun 2008 16:38:01 +0000 (UTC)
	(envelope-from andre@freebsd.org)
Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2])
	by mx1.freebsd.org (Postfix) with ESMTP id C1DD38FC17
	for <freebsd-net@freebsd.org>; Thu, 12 Jun 2008 16:38:00 +0000 (UTC)
	(envelope-from andre@freebsd.org)
Received: (qmail 88804 invoked from network); 12 Jun 2008 15:33:05 -0000
Received: from localhost (HELO [127.0.0.1]) ([127.0.0.1])
	(envelope-sender <andre@freebsd.org>)
	by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP
	for <yonyossef.lists@gmail.com>; 12 Jun 2008 15:33:05 -0000
Message-ID: <485150E8.7050903@freebsd.org>
Date: Thu, 12 Jun 2008 18:38:00 +0200
From: Andre Oppermann <andre@freebsd.org>
User-Agent: Thunderbird 1.5.0.14 (Windows/20071210)
MIME-Version: 1.0
To: Yony Yossef <yonyossef.lists@gmail.com>
References: <20def4870806120817q5b755805hfafa0d0d1523f2ad@mail.gmail.com>
In-Reply-To: <20def4870806120817q5b755805hfafa0d0d1523f2ad@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-net@freebsd.org, liranl@mellanox.co.il
Subject: Re: TSO bug in FreeBSD 7.0 ?
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: Thu, 12 Jun 2008 16:38:01 -0000

Yony Yossef wrote:
> Hi freebsd-net,
> 
> I'm seeing mbuf chains larger than 64K being sent down by FreeBSD 7 when TSO
> is enabled.
> Then my driver crashes in bus_dmamap_load_mbuf_sg (error=EINVAL).
> I'm printing the mbuf m_pkthdr.len size right after the DEQUEUE from the
> stack:
> 
> IFQ_DRV_DEQUEUE(&dev->if_snd, m_head);
> if (m_head == NULL)
>    break;
>         if (m_head->m_pkthdr.len > 65000) {
>             printf("TSO packet mbuf len:%d\n", m_head->m_pkthdr.len);
>         }
> and the output is:
> 
> ....
> TSO packet mbuf len:65387
> TSO packet mbuf len:65417
> TSO packet mbuf len:65447
> TSO packet mbuf len:65477
> TSO packet mbuf len:65507
> TSO packet mbuf len:65537
> mtnic0: bus_dmamap_load_mbuf_sg error: 22
> xmit_failure:12
> ...
> 
> Note the 65537, I've also seen TSO packets sized 65542.
> 
> There's this old thread talking about it:
> http://unix.derkeiler.com/Mailing-Lists/FreeBSD/net/2007-02/msg00312.html
> but I've seen no solution for this bug.
> 
> Is there a fix for that?

This bug is supposed to be fixed and the fix should also be included
in 7.0.  The other users of TSO reported no more overflows.  I'll have
another look whether later changes may have had an effect.

-- 
Andre