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alistair23-linux
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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>
hifive-unleashed-5.1
Rafael J. Wysocki 2015-07-30 01:45:07 +02:00
parent 194d99c7e3
commit fdd320da84
1 changed files with 10 additions and 3 deletions
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13
drivers/cpufreq/cpufreq.c
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@ -2471,10 +2471,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
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 cpufreq_driver *driver_data)
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);