From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757163AbcANXWd (ORCPT ); Thu, 14 Jan 2016 18:22:33 -0500 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:38169 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757075AbcANXWa (ORCPT ); Thu, 14 Jan 2016 18:22:30 -0500 X-Sasl-enc: QJ2rVlS/dd48Kvv2xJtH+v6/9MpQCJgt/sCisjThU5/v 1452813749 Subject: Re: [PATCH v2] net: preserve IP control block during GSO segmentation To: Florian Westphal , David Miller References: <145225570625.30903.13936642758071448458.stgit@zurg> <20160113.155112.119405358547782630.davem@davemloft.net> <20160113233628.GA10507@breakpoint.cc> Cc: koct9i@gmail.com, netdev@vger.kernel.org, dev@openvswitch.org, cascardo@redhat.com, edumazet@google.com, linux-kernel@vger.kernel.org, pshelar@nicira.com, xiyou.wangcong@gmail.com From: Hannes Frederic Sowa Message-ID: <56982DB1.50304@stressinduktion.org> Date: Fri, 15 Jan 2016 00:22:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <20160113233628.GA10507@breakpoint.cc> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14.01.2016 00:36, Florian Westphal wrote: > David Miller wrote: >> From: Konstantin Khlebnikov >> Date: Fri, 08 Jan 2016 15:21:46 +0300 >> >>> Skb_gso_segment() uses skb control block during segmentation. >>> This patch adds 32-bytes room for previous control block which >>> will be copied into all resulting segments. >>> >>> This patch fixes kernel crash during fragmenting forwarded packets. >>> Fragmentation requires valid IP CB in skb for clearing ip options. >>> Also patch removes custom save/restore in ovs code, now it's redundant. >>> >>> Signed-off-by: Konstantin Khlebnikov >>> Link: http://lkml.kernel.org/r/CALYGNiP-0MZ-FExV2HutTvE9U-QQtkKSoE--KN=JQE5STYsjAA@mail.gmail.com >> >> If this works I definitely prefer this approach to the other patch >> where the CB is copied back and forth. > > I quite frankly don't care and just like you to apply one or the other; > use coin toss if needed :-} > > I would prefer to use a on-stack state since there is no need to > use skb->cb (no queueing) but when I gave it a try it got out of hand > rather quick :-/ Be careful with the encap counter within SKB_GSO_CB when trying to put it on the stack. Bye, Hannes