From owner-cvs-src@FreeBSD.ORG Tue Dec 12 13:16:14 2006 Return-Path: X-Original-To: cvs-src@FreeBSD.org Delivered-To: cvs-src@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 203F116A4FD; Tue, 12 Dec 2006 13:16:14 +0000 (UTC) (envelope-from ticso@cicely12.cicely.de) Received: from raven.bwct.de (raven.bwct.de [85.159.14.73]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3B93843E45; Tue, 12 Dec 2006 13:12:52 +0000 (GMT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de ([10.1.1.7]) by raven.bwct.de (8.13.4/8.13.4) with ESMTP id kBCDDhFM043587; Tue, 12 Dec 2006 14:13:44 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [10.1.1.14]) by cicely5.cicely.de (8.13.4/8.13.4) with ESMTP id kBCDDZgc042500 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 12 Dec 2006 14:13:36 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.13.4/8.13.3) with ESMTP id kBCDDZZC074702; Tue, 12 Dec 2006 14:13:35 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.13.4/8.13.3/Submit) id kBCDDYcm074701; Tue, 12 Dec 2006 14:13:34 +0100 (CET) (envelope-from ticso) Date: Tue, 12 Dec 2006 14:13:34 +0100 From: Bernd Walter To: Luigi Rizzo , imp@FreeBSD.org Message-ID: <20061212131333.GU54209@cicely12.cicely.de> References: <200612081036.kB8AakMD029277@repoman.freebsd.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200612081036.kB8AakMD029277@repoman.freebsd.org> X-Operating-System: FreeBSD cicely12.cicely.de 5.4-STABLE alpha User-Agent: Mutt/1.5.9i X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED=-1.8, BAYES_00=-2.599 autolearn=ham version=3.1.7 X-Spam-Checker-Version: SpamAssassin 3.1.7 (2006-10-05) on cicely12.cicely.de Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/net if_ethersubr.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: ticso@cicely.de List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Dec 2006 13:16:14 -0000 On Fri, Dec 08, 2006 at 10:36:46AM +0000, Luigi Rizzo wrote: > luigi 2006-12-08 10:36:45 UTC > > FreeBSD src repository > > Modified files: > sys/net if_ethersubr.c > Log: > Fix an oscure bug triggered by a recent change in kern_socket.c. > The symptoms were that outgoing DHCP requests for diskless kernels > had the IP header corrupt. After long investigations, the source of > the problem was found in ether_output() - for SIMPLEX interfaces > and broadcast traffic, a copy of the packet is passed back to the kernel > through if_simloop(). However if_simloop() modifies the mbuf, while > the copy obtained through m_copym() is a readonly one. > > The bug has been there forever, but it has been triggered only recently > by a change in sosend_dgram() which passed down mbufs with sufficient > space to prepend the header. > > This fix is trivial - use m_dup() instead of m_copy() to create > the copy. As an alternative, we could try and modify if_simloop() > to play safely with readonly mbufs, but i don't think it is worthwhile > because 1) this is a relatively infrequent code path so we do not need > to worry too much about performance, and 2) the cost of doing an > extra m_pullup in if_simloop() is probably the same as doing the > copy of the cluster, anyways. This change produces an alignment panic on arm. Reverting it gets my system back to live. Sending DHCP Discover packet from interface ate0 (00:0e:42:02:00:21) Fatal kernel mode data abort: 'Alignment Fault 3' trapframe: 0xc529fd98 FSR=000000f3, FAR=c08e181e, spsr=20000013 r0 =c08a2e00, r1 =c529fdec, r2 =00000045, r3 =000005d0 r4 =c08e180e, r5 =c01eb8a0, r6 =00000014, r7 =00000000 r8 =00000000, r9 =c01fb9ac, r10=c079acb8, r11=c529fe10 r12=c08a2e00, ssp=c529fde4, slr=c00d2670, pc =c00e2afc [thread pid 11 tid 100004 ] Stopped at ip_input+0x9c: ldr r1, [r4, #0x010] -- B.Walter http://www.bwct.de http://www.fizon.de bernd@bwct.de info@bwct.de support@fizon.de