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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 ADA26C43603 for ; Mon, 9 Dec 2019 12:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7DFD6207FD for ; Mon, 9 Dec 2019 12:01:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="oybjfxfC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727610AbfLIMBq (ORCPT ); Mon, 9 Dec 2019 07:01:46 -0500 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:34890 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726687AbfLIMBp (ORCPT ); Mon, 9 Dec 2019 07:01:45 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1575892904; x=1607428904; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=XvRR7gQY2FQJatuw/ophADlxtuoMusOU93AHjmf9lGY=; b=oybjfxfCv7PSTdkGnD1iiMGgAMMifi+32iWjBWqXnZ1fU7fwTNwXnQnn g2ja/QcgQnHiowCHKnJxicWJKKmpWanRcr+ry9KCTIDKAtFZ0Hstx/igY ImC3/7u0vRtrJ8hkLMI8qlmwtZDX2GKB+8RPwU/0zR0u5x+tjBvR0l1ZI s=; IronPort-SDR: PmvwQo4VnzBLjfnNJGwXkqt+n4PosgQshR9n6DuHBw9xplP0Z4ts5Y/FFs9acKdrfrJ6NRwsV0 BEcmp/w7sxmQ== X-IronPort-AV: E=Sophos;i="5.69,294,1571702400"; d="scan'208";a="7663811" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-1e-c7c08562.us-east-1.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP; 09 Dec 2019 12:01:42 +0000 Received: from EX13MTAUEA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan2.iad.amazon.com [10.40.159.162]) by email-inbound-relay-1e-c7c08562.us-east-1.amazon.com (Postfix) with ESMTPS id E58CB240AF1; Mon, 9 Dec 2019 12:01:39 +0000 (UTC) Received: from EX13D32EUC003.ant.amazon.com (10.43.164.24) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 9 Dec 2019 12:01:39 +0000 Received: from EX13D32EUC003.ant.amazon.com (10.43.164.24) by EX13D32EUC003.ant.amazon.com (10.43.164.24) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 9 Dec 2019 12:01:38 +0000 Received: from EX13D32EUC003.ant.amazon.com ([10.43.164.24]) by EX13D32EUC003.ant.amazon.com ([10.43.164.24]) with mapi id 15.00.1367.000; Mon, 9 Dec 2019 12:01:38 +0000 From: "Durrant, Paul" To: =?iso-8859-1?Q?Roger_Pau_Monn=E9?= CC: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , "Juergen Gross" , Stefano Stabellini , "Boris Ostrovsky" Subject: RE: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed Thread-Topic: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed Thread-Index: AQHVq3SCoU35oX1INEGjFwMD1PQM5aexs7UAgAAEsBA= Date: Mon, 9 Dec 2019 12:01:38 +0000 Message-ID: <19b5c2fa36b842e58bbdddd602c4e672@EX13D32EUC003.ant.amazon.com> References: <20191205140123.3817-1-pdurrant@amazon.com> <20191205140123.3817-3-pdurrant@amazon.com> <20191209113926.GS980@Air-de-Roger> In-Reply-To: <20191209113926.GS980@Air-de-Roger> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.43.164.211] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Roger Pau Monn=E9 > Sent: 09 December 2019 11:39 > To: Durrant, Paul > Cc: linux-kernel@vger.kernel.org; xen-devel@lists.xenproject.org; Juergen > Gross ; Stefano Stabellini ; > Boris Ostrovsky > Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced t= o > closed >=20 > On Thu, Dec 05, 2019 at 02:01:21PM +0000, Paul Durrant wrote: > > Only force state to closed in the case when the toolstack may need to > > clean up. This can be detected by checking whether the state in xenstor= e > > has been set to closing prior to device removal. >=20 > I'm not sure I see the point of this, I would expect that a failure to > probe or the removal of the device would leave the xenbus state as > closed, which is consistent with the actual driver state. >=20 > Can you explain what's the benefit of leaving a device without a > driver in such unknown state? >=20 If probe fails then I think it should leave the state alone. If the state i= s moved to closed then basically you just killed that connection to the gue= st (as the frontend will normally close down when it sees this change) so, = if the probe failure was due to a bug in blkback or, e.g., a transient reso= urce issue then it's game over as far as that guest goes. The ultimate goal here is PV backend re-load that is completely transparent= to the guest. Modifying anything in xenstore compromises that so we need t= o be careful. Paul