From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756757AbYCNIJM (ORCPT ); Fri, 14 Mar 2008 04:09:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753120AbYCNII5 (ORCPT ); Fri, 14 Mar 2008 04:08:57 -0400 Received: from public.id2-vpn.continvity.gns.novell.com ([195.33.99.129]:23670 "EHLO public.id2-vpn.continvity.gns.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752116AbYCNIIz convert rfc822-to-8bit (ORCPT ); Fri, 14 Mar 2008 04:08:55 -0400 Message-Id: <47DA40D4.76E4.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 7.0.3 Beta Date: Fri, 14 Mar 2008 08:09:40 +0000 From: "Jan Beulich" To: "H. Peter Anvin" Cc: , , Subject: Re: [RFC] x86: bitops asm constraint fixes References: <47D8FD33.76E4.0078.0@novell.com> <47DA2E6F.5080907@zytor.com> In-Reply-To: <47DA2E6F.5080907@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> "H. Peter Anvin" 14.03.08 08:51 >>> >Jan Beulich wrote: >> >> I'd really like understand, though, what the policy of (not) having a >> "memory" clobber in these operations is - currently, this appears to >> be totally inconsistent. Also, many comments of the non-atomic >> functions say those may also be re-ordered - this contradicts the use >> of "asm volatile" in there, which again I'd like to understand. >> > >In general, proper "m" constraints are better than "memory" clobbers, >since they give gcc more information. Note that the "m" constraint >doesn't actually have to be *manifest* in the assembly string. ... which is the case with the patch applied. So am I taking this as 'yes, a proper re-write of these routines is worthwhile'? But - you didn't comment on the other issues raised, so before getting to that I'll have to wait to see what's the reason (if any) for the other anomalies. Jan