From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754779Ab2BQWKM (ORCPT ); Fri, 17 Feb 2012 17:10:12 -0500 Received: from e32.co.us.ibm.com ([32.97.110.150]:41485 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752651Ab2BQWKK (ORCPT ); Fri, 17 Feb 2012 17:10:10 -0500 Date: Fri, 17 Feb 2012 14:10:05 -0800 From: "Paul E. McKenney" To: Hugh Dickins Cc: "Paul E. McKenney" , linux-kernel@vger.kernel.org Subject: Re: [PATCH next] rcu: stop spurious warnings from synchronize_sched_expedited Message-ID: <20120217221005.GX2976@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12021722-3270-0000-0000-0000041E8345 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 17, 2012 at 01:20:31PM -0800, Hugh Dickins wrote: > synchronize_sched_expedited() is spamming CONFIG_DEBUG_PREEMPT=y > users with an unintended warning from the cpu_is_offline() check: > use raw_smp_processor_id() instead of smp_processor_id() there. Good catch! Queued. Thanx, Paul > Signed-off-by: Hugh Dickins > --- > > kernel/rcutree.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- next/kernel/rcutree.c 2012-02-17 08:02:15.680065066 -0800 > +++ linux/kernel/rcutree.c 2012-02-17 10:41:18.764003566 -0800 > @@ -2014,7 +2014,7 @@ void synchronize_sched_expedited(void) > /* Note that atomic_inc_return() implies full memory barrier. */ > firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started); > get_online_cpus(); > - WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); > + WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); > > /* > * Each pass through the following loop attempts to force a >