cpufreq: Lock CPU online/offline in cpufreq_register_driver()
To protect against races with concurrent CPU online/offline, call
get_online_cpus() before registering a cpufreq driver.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 24e4ba5..0f4e96f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2471,10 +2471,14 @@
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 @@
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 @@
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);