From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753373AbbAOLHY (ORCPT ); Thu, 15 Jan 2015 06:07:24 -0500 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:43580 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753323AbbAOLHW (ORCPT ); Thu, 15 Jan 2015 06:07:22 -0500 Message-ID: <54B79F5F.1040806@de.ibm.com> Date: Thu, 15 Jan 2015 12:07:11 +0100 From: Christian Borntraeger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: David Vrabel , linux-kernel@vger.kernel.org CC: linux-arch@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [Xen-devel] [PATCH 3/8] x86/xen/p2m: Replace ACCESS_ONCE with READ_ONCE References: <1421312314-72330-1-git-send-email-borntraeger@de.ibm.com> <1421312314-72330-4-git-send-email-borntraeger@de.ibm.com> <54B799DC.1050008@citrix.com> In-Reply-To: <54B799DC.1050008@citrix.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15011511-0021-0000-0000-0000028DF1C4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 15.01.2015 um 11:43 schrieb David Vrabel: > On 15/01/15 08:58, Christian Borntraeger wrote: >> ACCESS_ONCE does not work reliably on non-scalar types. For >> example gcc 4.6 and 4.7 might remove the volatile tag for such >> accesses during the SRA (scalar replacement of aggregates) step >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145) >> >> Change the p2m code to replace ACCESS_ONCE with READ_ONCE. > > Acked-by: David Vrabel Thanks > Let me know if you want me to merge this via the Xen tree. With your Acked-by, I can easily carry this in my tree. We can then ensure that this patch is merged before the ACCESS_ONCE is made stricter - making bisecting easier. Christian