From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 1/3] xen-netback: make feature-rx-notify mandatory Date: Thu, 23 Oct 2014 12:52:29 +0100 Message-ID: <5448EBFD.7070004@citrix.com> References: <1413983335-8307-1-git-send-email-david.vrabel@citrix.com> <1413983335-8307-2-git-send-email-david.vrabel@citrix.com> <20141023111629.GE9188@zion.uk.xensource.com> <20141023113206.GF9188@zion.uk.xensource.com> <5448E892.9010307@citrix.com> <20141023114453.GH9188@zion.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , Ian Campbell To: Wei Liu Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:56213 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754630AbaJWLwc (ORCPT ); Thu, 23 Oct 2014 07:52:32 -0400 In-Reply-To: <20141023114453.GH9188@zion.uk.xensource.com> Sender: netdev-owner@vger.kernel.org List-ID: On 23/10/14 12:44, Wei Liu wrote: > On Thu, Oct 23, 2014 at 12:37:54PM +0100, David Vrabel wrote: >> On 23/10/14 12:32, Wei Liu wrote: >>> On Thu, Oct 23, 2014 at 12:16:29PM +0100, Wei Liu wrote: >>>> On Wed, Oct 22, 2014 at 02:08:53PM +0100, David Vrabel wrote: >>>>> Frontends that do not provide feature-rx-notify may stall because >>>>> netback depends on the notification from frontend to wake the guest Rx >>>>> thread (even if can_queue is false). >>>>> >>>>> This could be fixed but feature-rx-notify was introduced in 2006 and I >>>>> am not aware of any frontends that do not implement this. >>>>> >>>>> Signed-off-by: David Vrabel >>>> >>>> Acked-by: Wei Liu >>> >>> While I can understand this patch by itself, can you elaborate a little >>> bit on how it affects later patches? Because what I'm thinking is that >>> this patch is not for stable while other two should go to stable. >> >> >From the cover letter: >> >> "The first patch is a prerequite. Removing support for frontends with >> feature-rx-notify makes it easier to reason about the correctness of >> netback since it no longer has to support this outdated and broken >> mode." >> > > I saw that. > > I think you should make it a little bit clearer. I'm not sure how I can make this any clearer. Perhaps you should wander over to my desk to discuss this in person? > The queue is not guaranteed to stop if we keep this feature. > >> The other patches do not meet the stable kernel requirements (they're >> too long one thing). >> > > Does length matter? I surely had written long patch for stable. >>From Documentation/stable_kernel_rules.txt: "- It cannot be bigger than 100 lines, with context." David