Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761430AbZAGV31 (ORCPT ); Wed, 7 Jan 2009 16:29:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752000AbZAGV3O (ORCPT ); Wed, 7 Jan 2009 16:29:14 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:40506 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751099AbZAGV3M (ORCPT ); Wed, 7 Jan 2009 16:29:12 -0500 Date: Wed, 7 Jan 2009 22:28:42 +0100 From: Ingo Molnar To: Linus Torvalds Cc: Steven Rostedt , Peter Zijlstra , paulmck@linux.vnet.ibm.com, Gregory Haskins , Matthew Wilcox , Andi Kleen , Chris Mason , Andrew Morton , Linux Kernel Mailing List , linux-fsdevel , linux-btrfs , Thomas Gleixner , Nick Piggin , Peter Morreale , Sven Dietrich Subject: Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning Message-ID: <20090107212842.GD4597@elte.hu> References: <1231279660.11687.121.camel@twins> <1231281801.11687.125.camel@twins> <1231283778.11687.136.camel@twins> <1231329783.11687.287.camel@twins> <1231347442.11687.344.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) 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: 851 Lines: 28 * Linus Torvalds wrote: > /* > * Even if the access succeeded (likely case), > * the cpu field may no longer be valid. FIXME: > * this needs to validate that we can do a > * get_cpu() and that we have the percpu area. s/get_cpu/cpu_rq ? > */ > if (cpu >= NR_CPUS) > break; > > if (!cpu_online(cpu)) > break; Regarding the FIXME, this should be safe already - at least on x86 we set up all the possible-cpus-mask per CPU areas during bootup. So any CPU that is online, will have a percpu area. (even in the most racy case) 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/