From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH] cpufreq: Lock CPU online/offline in cpufreq_register_driver() Date: Thu, 30 Jul 2015 11:18:01 +0530 Message-ID: <20150730054801.GJ5100@linux> References: <2126034.7irFieEIfi@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f47.google.com ([209.85.220.47]:34515 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750741AbbG3FsH (ORCPT ); Thu, 30 Jul 2015 01:48:07 -0400 Received: by pacan13 with SMTP id an13so17969559pac.1 for ; Wed, 29 Jul 2015 22:48:07 -0700 (PDT) Content-Disposition: inline In-Reply-To: <2126034.7irFieEIfi@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" Cc: Linux PM list , Linux Kernel Mailing List , Russell King On 30-07-15, 01:45, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > To protect against races with concurrent CPU online/offline, call > get_online_cpus() before registering a cpufreq driver. > > Signed-off-by: Rafael J. Wysocki > --- > drivers/cpufreq/cpufreq.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > Index: linux-pm/drivers/cpufreq/cpufreq.c > =================================================================== > --- linux-pm.orig/drivers/cpufreq/cpufreq.c > +++ linux-pm/drivers/cpufreq/cpufreq.c > @@ -2471,10 +2471,14 @@ int cpufreq_register_driver(struct cpufr > > pr_debug("trying to register driver %s\n", driver_data->name); > > + /* Protect against concurrent CPU online/offline. */ > + get_online_cpus(); > + > write_lock_irqsave(&cpufreq_driver_lock, flags); > if (cpufreq_driver) { > write_unlock_irqrestore(&cpufreq_driver_lock, flags); > - return -EEXIST; > + ret = -EEXIST; > + goto out; > } > cpufreq_driver = driver_data; > write_unlock_irqrestore(&cpufreq_driver_lock, flags); > @@ -2513,7 +2517,10 @@ int cpufreq_register_driver(struct cpufr > register_hotcpu_notifier(&cpufreq_cpu_notifier); > pr_debug("driver %s up and running\n", driver_data->name); > > - return 0; > +out: > + put_online_cpus(); > + return ret; > + > err_if_unreg: > subsys_interface_unregister(&cpufreq_interface); > err_boost_unreg: > @@ -2523,7 +2530,7 @@ err_null_driver: > write_lock_irqsave(&cpufreq_driver_lock, flags); > cpufreq_driver = NULL; > write_unlock_irqrestore(&cpufreq_driver_lock, flags); > - return ret; > + goto out; > } > EXPORT_SYMBOL_GPL(cpufreq_register_driver); Acked-by: Viresh Kumar -- viresh