From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755364Ab0DSOeF (ORCPT ); Mon, 19 Apr 2010 10:34:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12769 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752886Ab0DSOeC (ORCPT ); Mon, 19 Apr 2010 10:34:02 -0400 Message-ID: <4BCC69D5.3050209@redhat.com> Date: Mon, 19 Apr 2010 17:33:57 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Glauber Costa CC: Peter Zijlstra , Jeremy Fitzhardinge , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Marcelo Tosatti , Zachary Amsden Subject: Re: [PATCH 1/5] Add a global synchronization point for pvclock References: <1271356648-5108-1-git-send-email-glommer@redhat.com> <1271356648-5108-2-git-send-email-glommer@redhat.com> <4BC8CA52.4090703@goop.org> <1271673545.1674.743.camel@laptop> <4BCC3584.1050501@redhat.com> <1271675100.1674.818.camel@laptop> <4BCC3A3E.9070909@redhat.com> <20100419142158.GD14158@mothafucka.localdomain> In-Reply-To: <20100419142158.GD14158@mothafucka.localdomain> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/19/2010 05:21 PM, Glauber Costa wrote: > >> Oh yes, just trying to avoid a patch with both atomic64_read() and >> ACCESS_ONCE(). >> > you're mixing the private version of the patch you saw with this one. > there isn't any atomic reads in here. I'll use a barrier then > This patch writes last_value atomically, but reads it non-atomically. A barrier is insufficient. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.