Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934961Ab0HFOx1 (ORCPT ); Fri, 6 Aug 2010 10:53:27 -0400 Received: from claw.goop.org ([74.207.240.146]:58234 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759702Ab0HFOxZ (ORCPT ); Fri, 6 Aug 2010 10:53:25 -0400 Message-ID: <4C5C21E3.1020004@goop.org> Date: Fri, 06 Aug 2010 07:53:23 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.7) Gecko/20100720 Fedora/3.1.1-1.fc13 Lightning/1.0b2pre Thunderbird/3.1.1 MIME-Version: 1.0 To: Jan Beulich CC: Peter Zijlstra , Xen-devel , Avi Kivity , Nick Piggin , Linux Kernel Mailing List Subject: Re: [PATCH RFC 02/12] x86/ticketlock: convert spin loop to C References: <1280761639.1923.213.camel@laptop> <4C56E1A1.6020005@goop.org> <4C5C1F80020000780000EA6D@vpn.id2.novell.com> In-Reply-To: <4C5C1F80020000780000EA6D@vpn.id2.novell.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 681 Lines: 23 On 08/06/2010 05:43 AM, Jan Beulich wrote: > You certainly mean "the compiler currently treats this as being:" - I > don't think there's a guarantee it'll always be doing so. > >> for (;;) { >> if (inc.tickets.head == inc.tickets.tail) >> goto out; >> ... >> } >> out: barrier(); >> } >> >> (Which would probably be a reasonable way to clarify the code.) > I therefore think it needs to be written this way. Agreed. J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/