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Commit fdd320da authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

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: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
parent 194d99c7

drivers/cpufreq/cpufreq.c

+10 −3
Original line number Original line Diff line number Diff line
@@ -2471,10 +2471,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) 




	pr_debug("trying to register driver %s\n", driver_data->name);

	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);

	write_lock_irqsave(&cpufreq_driver_lock, flags);

	if (cpufreq_driver) {

	if (cpufreq_driver) {

		write_unlock_irqrestore(&cpufreq_driver_lock, flags);

		write_unlock_irqrestore(&cpufreq_driver_lock, flags);

		return -EEXIST;

		ret = -EEXIST;

		goto out;

	}

	}

	cpufreq_driver = driver_data;

	cpufreq_driver = driver_data;

	write_unlock_irqrestore(&cpufreq_driver_lock, flags);

	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -2513,7 +2517,10 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) 
	register_hotcpu_notifier(&cpufreq_cpu_notifier);

	register_hotcpu_notifier(&cpufreq_cpu_notifier);

	pr_debug("driver %s up and running\n", driver_data->name);

	pr_debug("driver %s up and running\n", driver_data->name);





	return 0;

out:

	put_online_cpus();

	return ret;



err_if_unreg:

err_if_unreg:

	subsys_interface_unregister(&cpufreq_interface);

	subsys_interface_unregister(&cpufreq_interface);

err_boost_unreg:

err_boost_unreg:
@@ -2523,7 +2530,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) 
	write_lock_irqsave(&cpufreq_driver_lock, flags);

	write_lock_irqsave(&cpufreq_driver_lock, flags);

	cpufreq_driver = NULL;

	cpufreq_driver = NULL;

	write_unlock_irqrestore(&cpufreq_driver_lock, flags);

	write_unlock_irqrestore(&cpufreq_driver_lock, flags);

	return ret;

	goto out;

}

}

EXPORT_SYMBOL_GPL(cpufreq_register_driver);

EXPORT_SYMBOL_GPL(cpufreq_register_driver);