From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752734AbaBXNuE (ORCPT ); Mon, 24 Feb 2014 08:50:04 -0500 Received: from mail-wi0-f170.google.com ([209.85.212.170]:42427 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752565AbaBXNuA (ORCPT ); Mon, 24 Feb 2014 08:50:00 -0500 Message-ID: <530B4E05.4020900@schaman.hu> Date: Mon, 24 Feb 2014 13:49:57 +0000 From: Zoltan Kiss User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Ian Campbell CC: wei.liu2@citrix.com, xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jonathan.davies@citrix.com Subject: Re: [PATCH net-next v5 4/9] xen-netback: Change RX path for mapped SKB fragments References: <1390253069-25507-1-git-send-email-zoltan.kiss@citrix.com> <1390253069-25507-5-git-send-email-zoltan.kiss@citrix.com> <1392745532.23084.65.camel@kazak.uk.xensource.com> <53093051.9040907@citrix.com> In-Reply-To: <53093051.9040907@citrix.com> 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 22/02/14 23:18, Zoltan Kiss wrote: > On 18/02/14 17:45, Ian Campbell wrote: >> On Mon, 2014-01-20 at 21:24 +0000, Zoltan Kiss wrote: >> >> Re the Subject: change how? Perhaps "handle foreign mapped pages on the >> guest RX path" would be clearer. > Ok, I'll do that. > >> >>> RX path need to know if the SKB fragments are stored on pages from >>> another >>> domain. >> Does this not need to be done either before the mapping change or at the >> same time? -- otherwise you have a window of a couple of commits where >> things are broken, breaking bisectability. > I can move this to the beginning, to keep bisectability. I've put it > here originally because none of these makes sense without the previous > patches. Well, I gave it a close look: to move this to the beginning as a separate patch I would need to put move a lot of definitions from the first patch to here (ubuf_to_vif helper, xenvif_zerocopy_callback etc.). That would be the best from bisect point of view, but from patch review point of view even worse than now. So the only option I see is to merge this with the first 2 patches, so it will be even bigger. And based on that principle, patch #6 and #8 should be merged there as well, as they solve corner cases introduced by the grant mapping. I don't know how much the bisecting requirements are written in stone. At this moment, all the separate patches compile, but after #2 there are new problems solved in #4, #6 and #8. If someone bisect in the middle of this range and run into these problems, they could quite easily figure out what went wrong looking at the adjacent patches. So I would recommend to keep this current order. What's your opinion? Zoli