Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935097AbYBVNgW (ORCPT ); Fri, 22 Feb 2008 08:36:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752894AbYBVNgJ (ORCPT ); Fri, 22 Feb 2008 08:36:09 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:52192 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752430AbYBVNgH (ORCPT ); Fri, 22 Feb 2008 08:36:07 -0500 Date: Fri, 22 Feb 2008 14:35:41 +0100 From: Ingo Molnar To: gregory.haskins@gmail.com Cc: Gregory Haskins , a.p.zijlstra@chello.nl, tglx@linutronix.de, rostedt@goodmis.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, bill.huey@gmail.com, kevin@hilman.org, cminyard@mvista.com, dsingleton@mvista.com, dwalker@mvista.com, npiggin@suse.de, dsaxena@plexity.net, ak@suse.de, gregkh@suse.de, sdietrich@novell.com, pmorreale@novell.com, mkohari@novell.com Subject: Re: [PATCH [RT] 05/14] rearrange rt_spin_lock sleep Message-ID: <20080222133541.GA8868@elte.hu> References: <20080221152504.4804.8724.stgit@novell1.haskins.net> <20080221152651.4804.4702.stgit@novell1.haskins.net> <47BECE30.8030100@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47BECE30.8030100@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 646 Lines: 17 * Gregory Haskins wrote: > My assumption is that the xchg() (inside update_current()) acts as an > effective wmb(). If xchg() does not have this property, then this > code is broken and patch 6/14 should also add a: xchg() is a strong implicit memory barrier, it implies smp_mb(). (historic sidenote: it was the very first SMP primitive we had in Linux.) Ingo -- 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/