cpufreq: Store cpufreq policies in a list

Policies available in the cpufreq framework are now linked together.
They are accessible via cpufreq_policy_list defined in the cpufreq
core.

[rjw: Fix from Yinghai Lu folded in]
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -40,6 +40,7 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data_fallback);
 static DEFINE_RWLOCK(cpufreq_driver_lock);
 static DEFINE_MUTEX(cpufreq_governor_lock);
+static LIST_HEAD(cpufreq_policy_list);
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* This one keeps track of the previously set governor of a removed CPU */
@@ -952,6 +953,7 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void)
 	if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
 		goto err_free_cpumask;
 
+	INIT_LIST_HEAD(&policy->policy_list);
 	return policy;
 
 err_free_cpumask:
@@ -964,6 +966,12 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void)
 
 static void cpufreq_policy_free(struct cpufreq_policy *policy)
 {
+	unsigned long flags;
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	list_del(&policy->policy_list);
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
 	free_cpumask_var(policy->related_cpus);
 	free_cpumask_var(policy->cpus);
 	kfree(policy);
@@ -1077,6 +1085,10 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
 		ret = cpufreq_add_dev_interface(policy, dev);
 		if (ret)
 			goto err_out_unregister;
+
+		write_lock_irqsave(&cpufreq_driver_lock, flags);
+		list_add(&policy->policy_list, &cpufreq_policy_list);
+		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 	}
 
 	cpufreq_init_policy(policy);

include/linux/cpufreq.h

@@ -82,6 +82,7 @@ struct cpufreq_policy {
 
 	struct cpufreq_real_policy	user_policy;
 
+	struct list_head        policy_list;
 	struct kobject		kobj;
 	struct completion	kobj_unregister;
 	int			transition_ongoing; /* Tracks transition status */