From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754539Ab2G3RsX (ORCPT ); Mon, 30 Jul 2012 13:48:23 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:60672 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754173Ab2G3RsV (ORCPT ); Mon, 30 Jul 2012 13:48:21 -0400 Date: Mon, 30 Jul 2012 10:42:18 -0700 From: "Paul E. McKenney" To: Feng Tang Cc: "Paul E. McKenney" , Len Brown , "Rafael J. Wysocki" , Linux Kernel Mail List Subject: Re: [Regression 3.4] tick_broadcast_mask is not restored after a CPU has been offline/onlined Message-ID: <20120730174218.GA30772@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120730151559.772d4055@feng-i7> <20120730133913.GK2556@linux.vnet.ibm.com> <20120730230747.7637112a@feng-i7> <20120730170847.GE2391@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120730170847.GE2391@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12073017-7282-0000-0000-00000B7CD057 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 30, 2012 at 10:08:47AM -0700, Paul E. McKenney wrote: > On Mon, Jul 30, 2012 at 11:07:47PM +0800, Feng Tang wrote: > > Hi Paul, > > > > On Mon, 30 Jul 2012 06:39:13 -0700 > > "Paul E. McKenney" wrote: > > > > > On Mon, Jul 30, 2012 at 03:15:59PM +0800, Feng Tang wrote: > > > > Hi All, > > > > > > > > When I debugged a suspend/resume bug, I found that tick_broadcast_mask is > > > > not restored for a CPU after it is offline/onlined since kernel 3.4, while > > > > it's fine for 3.3. > > > > > > Could you please try 3.5? > > > > Yes, it's the same for 3.5 > > Thank you for checking, Feng. > > Len, the comment above the change says: > > /* > * FIXME: Design the ACPI notification to make it once per > * system instead of once per-cpu. This condition is a hack > * to make the code that updates C-States be called once. > */ > > Is it time for this design-level change? Or is there something obvious > that I missed when fixing the smp_processor_id() splat? > > I could revert back, but use raw_smp_processor_id() rather than > smp_processor_id(), but that feels like papering over a problem rather > than fixing it. But should papering be appropriate, here is the patch. Thanx, Paul ------------------------------------------------------------------------ ACPI: Repair fix to unprotected smp_processor_id() Commit 9505626d (ACPI: Fix unprotected smp_processor_id() in acpi_processor_cst_has_changed()) introduced a suspend/resume bug. This commit therefore introduces a bug-for-bug compatible fix for the original problem. Reported-by: Feng Tang Signed-off-by: Paul E. McKenney diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 47a8caa..19c151a 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1218,7 +1218,8 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) * to make the code that updates C-States be called once. */ - if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) { + if (raw_smp_processor_id() == 0 && + cpuidle_get_driver() == &acpi_idle_driver) { cpuidle_pause_and_lock(); /* Protect against cpu-hotplug */