Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932161AbWCCUR2 (ORCPT ); Fri, 3 Mar 2006 15:17:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932211AbWCCUR1 (ORCPT ); Fri, 3 Mar 2006 15:17:27 -0500 Received: from mx1.redhat.com ([66.187.233.31]:51431 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932161AbWCCUR0 (ORCPT ); Fri, 3 Mar 2006 15:17:26 -0500 From: David Howells In-Reply-To: References: <32518.1141401780@warthog.cambridge.redhat.com> <1146.1141404346@warthog.cambridge.redhat.com> To: Linus Torvalds Cc: David Howells , akpm@osdl.org, ak@suse.de, mingo@redhat.com, jblunck@suse.de, bcrl@linux.intel.com, matthew@wil.cx, linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: Memory barriers and spin_unlock safety X-Mailer: MH-E 7.92+cvs; nmh 1.1; GNU Emacs 22.0.50.4 Date: Fri, 03 Mar 2006 20:17:07 +0000 Message-ID: <5041.1141417027@warthog.cambridge.redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 559 Lines: 16 Linus Torvalds wrote: > Note that _normal_ writes never need an SFENCE, because they are ordered > by the core. > > The reason to use SFENCE is because of _special_ writes. I suspect, then, that x86_64 should not have an SFENCE for smp_wmb(), and that only io_wmb() should have that. David - 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/