Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932638Ab2B1Nam (ORCPT ); Tue, 28 Feb 2012 08:30:42 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:57215 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932400Ab2B1Nak (ORCPT ); Tue, 28 Feb 2012 08:30:40 -0500 Date: Tue, 28 Feb 2012 05:30:13 -0800 From: "Paul E. McKenney" To: Yong Zhang Cc: deepthi@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, lenb@kernel.org, linux-acpi@vger.kernel.org Subject: Re: [PATCH RFC] acpi: Fix unprotected smp_processor_id() in acpi_processor_cst_has_changed() Message-ID: <20120228133013.GE2465@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120223205805.GA31838@linux.vnet.ibm.com> <20120228071943.GE1112@zhy> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120228071943.GE1112@zhy> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12022813-6148-0000-0000-000003D0964C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2190 Lines: 57 On Tue, Feb 28, 2012 at 03:19:43PM +0800, Yong Zhang wrote: > On Thu, Feb 23, 2012 at 12:58:05PM -0800, Paul E. McKenney wrote: > > The acpi_processor_cst_has_changed() function is invoked from a > > CPU_ONLINE or CPU_DEAD function, which might well execute on CPU 0 > > even though the CPU being hotplugged is some other CPU. In addition, > > acpi_processor_cst_has_changed() invokes smp_processor_id() without > > protection, resulting in splats when onlining CPUs. > > > > This commit therefore changes the smp_processor_id() to pr->id, as is > > used elsewhere in the code, for example, in acpi_processor_add(). > > > > This works for me, but I don't claim to understand ACPI. > > > > Signed-off-by: Paul E. McKenney > > Got the same warning. > And the patch works on my side. > > Tested-by: Yong Zhang Thank you, I have added your Tested-by (and Srivatsa's Reviewed-by, for that matter). Any takers for this, or should I just push it up the -tip tree? Thanx, Paul > > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c > > index 0e8e2de..9e57b06 100644 > > --- a/drivers/acpi/processor_idle.c > > +++ b/drivers/acpi/processor_idle.c > > @@ -1159,8 +1159,7 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr) > > * to make the code that updates C-States be called once. > > */ > > > > - if (smp_processor_id() == 0 && > > - cpuidle_get_driver() == &acpi_idle_driver) { > > + if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) { > > > > cpuidle_pause_and_lock(); > > /* Protect against cpu-hotplug */ > > > > -- > > 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/ > > -- > Only stand for myself > -- 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/