From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH] cpufreq: Lock CPU online/offline in cpufreq_register_driver() Date: Thu, 30 Jul 2015 01:45:07 +0200 Message-ID: <2126034.7irFieEIfi@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from v094114.home.net.pl ([79.96.170.134]:40959 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753499AbbG2XSL (ORCPT ); Wed, 29 Jul 2015 19:18:11 -0400 Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Linux PM list Cc: Linux Kernel Mailing List , Viresh Kumar , Russell King 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);