From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932517Ab1KBO4a (ORCPT ); Wed, 2 Nov 2011 10:56:30 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:41652 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753369Ab1KBO41 (ORCPT ); Wed, 2 Nov 2011 10:56:27 -0400 X-Authority-Analysis: v=1.1 cv=rFxaVhpzdNKRsWyFDFmDbYx/QEtlW7L1Gw9MiLxO4aw= c=1 sm=0 a=nDqYd8iKHsYA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:17 a=meVymXHHAAAA:8 a=xUQEayChb4KHRQSXB00A:9 a=PUjeQqilurYA:10 a=jeBq3FmKZ4MA:10 a=ZycB6UtQUfgMyuk2+PxD7w==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.80.29 Message-ID: <1320245786.4793.32.camel@gandalf.stny.rr.com> Subject: Re: linux-next 20111025: warnings in rcu_idle_exit_common()/rcu_idle_enter_common() From: Steven Rostedt To: paulmck@linux.vnet.ibm.com Cc: Wu Fengguang , "linux-kernel@vger.kernel.org" , Ingo Molnar , Lai Jiangshan , Frederic Weisbecker , Carsten Emde Date: Wed, 02 Nov 2011 10:56:26 -0400 In-Reply-To: <20111102144403.GA22445@linux.vnet.ibm.com> References: <20111031082634.GA10348@localhost> <20111031095152.GL6160@linux.vnet.ibm.com> <20111031104325.GA25808@localhost> <20111031114142.GA32555@localhost> <20111031121951.GM6160@linux.vnet.ibm.com> <1320075882.4793.4.camel@gandalf.stny.rr.com> <20111101003434.GR6160@linux.vnet.ibm.com> <20111101070720.GA22936@localhost> <20111101160014.GH2287@linux.vnet.ibm.com> <20111101163212.GA19501@localhost> <20111102144403.GA22445@linux.vnet.ibm.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.0.3-2 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-11-02 at 07:44 -0700, Paul E. McKenney wrote: > rcu: Fix idle-task checks > > RCU has traditionally relied on idle_cpu() to determine whether a given > CPU is running in the context of an idle task, but recent changes have > invalidated this approach. Correct. idle_cpu() returns if the CPU is idle or not, not if the CPU is running the idle thread. If the CPU wakes up on the idle thread and there's tasks on the run queue, then idle_cpu() will return false, even though the task running is the idle thread. But the CPU itself is not technically idle. Acked-by: Steven Rostedt -- Steve