From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 0/2] pktgen: Clone skb to avoid corruption of skbs in ndo_start_xmit methods (v3) Date: Fri, 29 Jul 2011 09:16:42 +0300 Message-ID: <20110729061642.GA9884@redhat.com> References: <1311105179-26408-1-git-send-email-nhorman@tuxdriver.com> <1311696338-4739-1-git-send-email-nhorman@tuxdriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Neil Horman , mashirle@us.ibm.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47292 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753847Ab1G2GQj (ORCPT ); Fri, 29 Jul 2011 02:16:39 -0400 Content-Disposition: inline In-Reply-To: <1311696338-4739-1-git-send-email-nhorman@tuxdriver.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Jul 26, 2011 at 12:05:36PM -0400, Neil Horman wrote: > Ok, after considering all your comments, Dave suggested this as an alternate > approach: > > 1) We create a new priv_flag, IFF_SKB_TX_SHARED, to identify drivers capable of > handling shared skbs. Default is to not set this flag > > 2) Modify ether_setup to enable this flag, under the assumption that any driver > calling this function is initalizing a real ethernet device and as such can > handle shared skbs since they don't tend to store state in the skb struct. > Pktgen can then query this flag when a user script attempts to issue the > clone_skb command and decide if it is to be alowed or not. > > 3) Audit the network drivers calling ether_setup to identify any code doing so > that can't actualy handle shared skbs and manually disable the new flag. There > are about 10 drivers in this category. > > Change notes: > v3) Fixed Erics note in which I tested the length of the passed in string rather > than its converted value for beign > 0 > > Thoughts/reviews aprpeciated. > Neil It might be a good idea to disable vhost-net zerocopy for such devices as well: these skbs are shared with userspace. Shirley, what do you think? -- MST