From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77488C43603 for ; Mon, 9 Dec 2019 11:57:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 492E32077B for ; Mon, 9 Dec 2019 11:57:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727643AbfLIL5p (ORCPT ); Mon, 9 Dec 2019 06:57:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:45710 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727163AbfLIL5p (ORCPT ); Mon, 9 Dec 2019 06:57:45 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 36E8EAEE9; Mon, 9 Dec 2019 11:57:43 +0000 (UTC) Subject: Re: [PATCH 1/4] xenbus: move xenbus_dev_shutdown() into frontend code... To: "Durrant, Paul" , "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" Cc: Boris Ostrovsky , Stefano Stabellini References: <20191205140123.3817-1-pdurrant@amazon.com> <20191205140123.3817-2-pdurrant@amazon.com> <38908166-6a4b-9dab-144c-71df691da167@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <74b1c655-e107-51dd-e719-05a750f324a5@suse.com> Date: Mon, 9 Dec 2019 12:57:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.12.19 12:55, Durrant, Paul wrote: >> -----Original Message----- >> From: Jürgen Groß >> Sent: 09 December 2019 11:34 >> To: Durrant, Paul ; linux-kernel@vger.kernel.org; >> xen-devel@lists.xenproject.org >> Cc: Boris Ostrovsky ; Stefano Stabellini >> >> Subject: Re: [PATCH 1/4] xenbus: move xenbus_dev_shutdown() into frontend >> code... >> >> On 05.12.19 15:01, Paul Durrant wrote: >>> ...and make it static >>> >>> xenbus_dev_shutdown() is seemingly intended to cause clean shutdown of >> PV >>> frontends when a guest is rebooted. Indeed the function waits for a >>> conpletion which is only set by a call to xenbus_frontend_closed(). >>> >>> This patch removes the shutdown() method from backends and moves >>> xenbus_dev_shutdown() from xenbus_probe.c into xenbus_probe_frontend.c, >>> renaming it appropriately and making it static. >> >> Is this a good move considering driver domains? > > I don't think it can have ever worked properly for driver domains, and with the rest of the patches a backend should be able go away and return unannounced (as long as the domain id is kept... for which patches need to be upstreamed into Xen). > >> >> At least I'd expect the commit message addressing the expected behavior >> with rebooting a driver domain and why this patch isn't making things >> worse. >> > > For a clean reboot I'd expect the toolstack to shut down the protocol before rebooting the driver domain, so the backend shutdown method is moot. And I don't believe re-startable driver domains were something that ever made it into support (because of the non-persistent domid problem). I can add something to the commit comment to that effect if you'd like. Yes, please do so. With this you can add my: Reviewed-by: Juergen Gross Juergen