Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161373Ab2JXVxT (ORCPT ); Wed, 24 Oct 2012 17:53:19 -0400 Received: from ogre.sisk.pl ([193.178.161.156]:35574 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161289Ab2JXVxP (ORCPT ); Wed, 24 Oct 2012 17:53:15 -0400 From: "Rafael J. Wysocki" To: Andreas Herrmann Cc: linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, Tejun Heo , stable@vger.kernel.org Subject: Re: [PATCH] cpufreq, powernow-k8: Remove usage of smp_processor_id() in preemptible code Date: Wed, 24 Oct 2012 23:57:11 +0200 Message-ID: <4061311.WJSyxPuklg@vostro.rjw.lan> User-Agent: KMail/4.8.5 (Linux/3.6.2-6-desktop; KDE/4.8.5; x86_64; ; ) In-Reply-To: <20121012151841.GA4571@alberich> References: <20121009193844.GC7724@alberich> <20121010124839.GA22448@alberich> <20121012151841.GA4571@alberich> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2801 Lines: 72 On Friday 12 of October 2012 17:18:41 Andreas Herrmann wrote: > > Commit 6889125b8b4e09c5e53e6ecab3433bed1ce198c9 > (cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU) > causes powernow-k8 to trigger a preempt warning, e.g.: > > BUG: using smp_processor_id() in preemptible [00000000] code: cpufreq/3776 > caller is powernowk8_target+0x20/0x49 > Pid: 3776, comm: cpufreq Not tainted 3.6.0 #9 > Call Trace: > [] debug_smp_processor_id+0xc7/0xe0 > [] powernowk8_target+0x20/0x49 > [] __cpufreq_driver_target+0x82/0x8a > [] cpufreq_governor_performance+0x4e/0x54 > [] __cpufreq_governor+0x8c/0xc9 > [] __cpufreq_set_policy+0x1a9/0x21e > [] store_scaling_governor+0x16f/0x19b > [] ? cpufreq_update_policy+0x124/0x124 > [] ? _raw_spin_unlock_irqrestore+0x2c/0x49 > [] store+0x60/0x88 > [] sysfs_write_file+0xf4/0x130 > [] vfs_write+0xb5/0x151 > [] sys_write+0x4a/0x71 > [] system_call_fastpath+0x16/0x1b > > Fix this by by always using work_on_cpu(). > > Cc: Tejun Heo > Cc: stable@vger.kernel.org > Signed-off-by: Andreas Herrmann Applied to linux-pm.git/linux-next as v3.7 material, will be included in the next linux-pm push. Thanks, Rafael > --- > drivers/cpufreq/powernow-k8.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c > index 129e80b..c16a3a5 100644 > --- a/drivers/cpufreq/powernow-k8.c > +++ b/drivers/cpufreq/powernow-k8.c > @@ -1052,14 +1052,7 @@ static int powernowk8_target(struct cpufreq_policy *pol, > struct powernowk8_target_arg pta = { .pol = pol, .targfreq = targfreq, > .relation = relation }; > > - /* > - * Must run on @pol->cpu. cpufreq core is responsible for ensuring > - * that we're bound to the current CPU and pol->cpu stays online. > - */ > - if (smp_processor_id() == pol->cpu) > - return powernowk8_target_fn(&pta); > - else > - return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta); > + return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta); > } > > /* Driver entry point to verify the policy and range of frequencies */ > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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/