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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 61837C43603 for ; Wed, 11 Dec 2019 10:06:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 33C102073D for ; Wed, 11 Dec 2019 10:06:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="XKsiYV/E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728660AbfLKKG5 (ORCPT ); Wed, 11 Dec 2019 05:06:57 -0500 Received: from esa1.hc3370-68.iphmx.com ([216.71.145.142]:40029 "EHLO esa1.hc3370-68.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728468AbfLKKG4 (ORCPT ); Wed, 11 Dec 2019 05:06:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1576058816; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=5u5G6DvrHHYulwWxXP6RstYPZT7qaXjQ0DriMESzSyA=; b=XKsiYV/EY89O7D0ldTwTbgnqW+fOWyYlkUtjBTmZlisWFeGi34qOJGts Ooa+j7xWDaDAxZwex4GwFsDq81OPcf9Dcb/w9Sc7kLSmVAghntOAlSuBH 7qs2hvhQZ0SAGqDB4nYKU6fWGsmO1SqfcXsKihxYsAkb7Ib4QuMgdGZXc c=; Authentication-Results: esa1.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none; spf=None smtp.pra=roger.pau@citrix.com; spf=Pass smtp.mailfrom=roger.pau@citrix.com; spf=None smtp.helo=postmaster@mail.citrix.com Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of roger.pau@citrix.com) identity=pra; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="roger.pau@citrix.com"; x-conformance=sidf_compatible Received-SPF: Pass (esa1.hc3370-68.iphmx.com: domain of roger.pau@citrix.com designates 162.221.158.21 as permitted sender) identity=mailfrom; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="roger.pau@citrix.com"; x-conformance=sidf_compatible; x-record-type="v=spf1"; x-record-text="v=spf1 ip4:209.167.231.154 ip4:178.63.86.133 ip4:195.66.111.40/30 ip4:85.115.9.32/28 ip4:199.102.83.4 ip4:192.28.146.160 ip4:192.28.146.107 ip4:216.52.6.88 ip4:216.52.6.188 ip4:162.221.158.21 ip4:162.221.156.83 ip4:168.245.78.127 ~all" Received-SPF: None (esa1.hc3370-68.iphmx.com: no sender authenticity information available from domain of postmaster@mail.citrix.com) identity=helo; client-ip=162.221.158.21; receiver=esa1.hc3370-68.iphmx.com; envelope-from="roger.pau@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: h/++TCBi6C1mtA3r2r4COIFU7QXU1SxGYa0kvs/AAIA/HzuKOgPkJTwyZ2lmqLf9XKazfUwH7c xINyLWFzaAoDqJ593kmfWd85AhzpISMMLYjKcm8czhMmqnA50DPrKQjrZXl8VN5Hm+mR3gEdMK 5CcgFiAZwpk8sYzqoJ38tPrchGtds4tWqkNkJpJ8sdb3UZWXIffyt+i4nmndyyvr7IwhjjiTCe H0gSssg35mwqkGBizjBWCehbnDyILPqGmgzL61k3AnZgBT6XMMYO4DkShwJKPdc3Zx/px8l0eM 5Ps= X-SBRS: 2.7 X-MesageID: 9642862 X-Ironport-Server: esa1.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.69,301,1571716800"; d="scan'208";a="9642862" Date: Wed, 11 Dec 2019 11:06:27 +0100 From: Roger Pau =?iso-8859-1?Q?Monn=E9?= To: Paul Durrant CC: , , "Juergen Gross" , Stefano Stabellini , "Boris Ostrovsky" Subject: Re: [Xen-devel] [PATCH v2 2/4] xenbus: limit when state is forced to closed Message-ID: <20191211100627.GI980@Air-de-Roger> References: <20191210113347.3404-1-pdurrant@amazon.com> <20191210113347.3404-3-pdurrant@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20191210113347.3404-3-pdurrant@amazon.com> User-Agent: Mutt/1.12.2 (2019-09-21) X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL03.citrite.net (10.69.22.127) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 10, 2019 at 11:33:45AM +0000, Paul Durrant wrote: > If a driver probe() fails then leave the xenstore state alone. There is no > reason to modify it as the failure may be due to transient resource > allocation issues and hence a subsequent probe() may succeed. > > If the driver supports re-binding then only force state to closed during > remove() only in the case when the toolstack may need to clean up. This can > be detected by checking whether the state in xenstore has been set to > closing prior to device removal. > > NOTE: Re-bind support is indicated by new boolean in struct xenbus_driver, > which defaults to false. Subsequent patches will add support to > some backend drivers. My intention was to specify whether you want to close the backends on unbind in sysfs, so that an user can decide at runtime, rather than having a hardcoded value in the driver. Anyway, I'm less sure whether such runtime tunable is useful at all, so let's leave it out and can always be added afterwards. At the end of day a user wrongly doing a rmmod blkback can always recover gracefully by loading blkback again with your proposed approach to leave connections open on module removal. Sorry for the extra work. Thanks, Roger.