cpufreq: remove policy from cpufreq_policy_list during suspend

cpufreq_policy_list is a list of active policies.  We do remove
policies from this list when all CPUs belonging to that policy are
removed.  But during system suspend we don't really free a policy
struct as it will be used again during resume, so we didn't remove
it from cpufreq_policy_list as well..

However, this is incorrect.  We are saying this policy isn't valid
anymore and must not be referenced (though we haven't freed it), but
it can still be used by code that iterates over cpufreq_policy_list.

Remove policy from this list during system suspend as well.
Of course, we must add it back whenever the first CPU belonging to
that policy shows up.

[rjw: Changelog]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -950,12 +950,6 @@ 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);
@@ -1069,12 +1063,12 @@ 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);
 	}
 
+	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);
 
 	kobject_uevent(&policy->kobj, KOBJ_ADD);
@@ -1280,6 +1274,11 @@ static int __cpufreq_remove_dev(struct device *dev,
 		if (cpufreq_driver->exit)
 			cpufreq_driver->exit(policy);
 
+		/* Remove policy from list of active policies */
+		write_lock_irqsave(&cpufreq_driver_lock, flags);
+		list_del(&policy->policy_list);
+		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
 		if (!frozen)
 			cpufreq_policy_free(policy);
 	} else {