From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [PATCH] pktgen: Clone skb to avoid corruption of skbs in ndo_start_xmit methods Date: Thu, 21 Jul 2011 15:14:32 -0700 Message-ID: <4E28A4C8.8040707@candelatech.com> References: <20110720020737.GB2692@neilslaptop.think-freely.org> <1311135855.3113.66.camel@edumazet-laptop> <20110720151827.GD12349@hmsreliant.think-freely.org> <20110721.150107.25773992475689131.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: nhorman@tuxdriver.com, eric.dumazet@gmail.com, jpirko@redhat.com, netdev@vger.kernel.org, adobriyan@gmail.com, robert.olsson@its.uu.se To: David Miller Return-path: Received: from mail.candelatech.com ([208.74.158.172]:57378 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753072Ab1GUWOx (ORCPT ); Thu, 21 Jul 2011 18:14:53 -0400 In-Reply-To: <20110721.150107.25773992475689131.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 07/21/2011 03:01 PM, David Miller wrote: > From: Neil Horman > Date: Wed, 20 Jul 2011 11:18:27 -0400 > >> On Wed, Jul 20, 2011 at 06:24:15AM +0200, Eric Dumazet wrote: >>> Le mardi 19 juillet 2011 =E0 22:07 -0400, Neil Horman a =E9crit : >>>>> >>>> I think this is a good idea. It lets pktgen dynamically make the = clone/share >>>> decision dynamically and only impacts performance for those system= s. >>>> >>> >>> Just let pktgen refuse to use clone_skb command for these devices. >>> >> copy that, This is by no means final, but what do you think of this?= If its >> agreeable to you, Ben, et al. I can add this to my local tree and st= art auditing >> all the drivers that may need to have the flag set. > > I think there is a much simpler solution. > > Set a flag in the SKB when pktgen does SKB sharing. > > In dev_queue_xmit() (or perhaps, dev_hard_start_xmit()), check the fl= ag > and if it's set then we copy the SKB. > > If this works, then we fix the crash and no driver changes are > necessary both now and in the future. Doesn't that make clone-skb in pktgen much less efficient in all cases? Thanks, Ben --=20 Ben Greear Candela Technologies Inc http://www.candelatech.com