From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751282Ab2GaEKC (ORCPT ); Tue, 31 Jul 2012 00:10:02 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:33615 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751455Ab2GaEKA (ORCPT ); Tue, 31 Jul 2012 00:10:00 -0400 Date: Mon, 30 Jul 2012 21:09:56 -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: <20120731040955.GD2423@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> <20120730174218.GA30772@linux.vnet.ibm.com> <20120731111832.435b8bd9@feng-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120731111832.435b8bd9@feng-i7> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12073104-5518-0000-0000-00000678191A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 31, 2012 at 11:18:32AM +0800, Feng Tang wrote: > Hi Paul, > > On Mon, 30 Jul 2012 10:42:18 -0700 > "Paul E. McKenney" wrote: > > > 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 > > Just found and have a patch to fix a typo in acpi processor_driver.c, which > could also fix this tick_broadcast_mask issue. > > Patch is in https://lkml.org/lkml/2012/7/30/483 > > So I think we don't need this "papering over" patch :) Very good, I have dropped it. Thanx, Paul > Thanks, > Feng > > > > > ------------------------------------------------------------------------ > > > > 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 */ > > >