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SubjectRe: [PATCH] cpufreq: Lock CPU online/offline in cpufreq_register_driver()
On 30-07-15, 01:45, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> 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>
> ---
> 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.kumar@linaro.org>

--
viresh


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