Commit 6fec833b authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: Add and use cpufreq policy locking guards 



Introduce "read" and "write" locking guards for cpufreq policies and use
them where applicable in the cpufreq core.

No intentional functional impact.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Acked-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Tested-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/8518682.T7Z3S40VBb@rjwysocki.net
parent 68974e3a

drivers/cpufreq/cpufreq.c

+54 −67
Original line number Diff line number Diff line
@@ -1009,17 +1009,16 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf) 
{

	struct cpufreq_policy *policy = to_policy(kobj);

	struct freq_attr *fattr = to_attr(attr);

	ssize_t ret = -EBUSY;



	if (!fattr->show)

		return -EIO;



	down_read(&policy->rwsem);

	guard(cpufreq_policy_read)(policy);



	if (likely(!policy_is_inactive(policy)))

		ret = fattr->show(policy, buf);

	up_read(&policy->rwsem);

		return fattr->show(policy, buf);



	return ret;

	return -EBUSY;

}



static ssize_t store(struct kobject *kobj, struct attribute *attr,
@@ -1027,17 +1026,16 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, 
{

	struct cpufreq_policy *policy = to_policy(kobj);

	struct freq_attr *fattr = to_attr(attr);

	ssize_t ret = -EBUSY;



	if (!fattr->store)

		return -EIO;



	down_write(&policy->rwsem);

	guard(cpufreq_policy_write)(policy);



	if (likely(!policy_is_inactive(policy)))

		ret = fattr->store(policy, buf, count);

	up_write(&policy->rwsem);

		return fattr->store(policy, buf, count);



	return ret;

	return -EBUSY;

}



static void cpufreq_sysfs_release(struct kobject *kobj)
@@ -1195,7 +1193,8 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp 
	if (cpumask_test_cpu(cpu, policy->cpus))

		return 0;



	down_write(&policy->rwsem);

	guard(cpufreq_policy_write)(policy);



	if (has_target())

		cpufreq_stop_governor(policy);
@@ -1206,7 +1205,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp 
		if (ret)

			pr_err("%s: Failed to start governor\n", __func__);

	}

	up_write(&policy->rwsem);



	return ret;

}
@@ -1226,9 +1225,10 @@ static void handle_update(struct work_struct *work) 
		container_of(work, struct cpufreq_policy, update);



	pr_debug("handle_update for cpu %u called\n", policy->cpu);

	down_write(&policy->rwsem);



	guard(cpufreq_policy_write)(policy);



	refresh_frequency_limits(policy);

	up_write(&policy->rwsem);

}



static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq,
@@ -1254,11 +1254,11 @@ static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy) 
	struct kobject *kobj;

	struct completion *cmp;



	down_write(&policy->rwsem);

	scoped_guard(cpufreq_policy_write, policy) {

		cpufreq_stats_free_table(policy);

		kobj = &policy->kobj;

		cmp = &policy->kobj_unregister;

	up_write(&policy->rwsem);

	}

	kobject_put(kobj);



	/*
@@ -1409,7 +1409,7 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy, 
	unsigned int j;

	int ret;



	down_write(&policy->rwsem);

	guard(cpufreq_policy_write)(policy);



	policy->cpu = cpu;

	policy->governor = NULL;
@@ -1586,10 +1586,7 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy, 
		goto out_destroy_policy;

	}



out_unlock:

	up_write(&policy->rwsem);



	return ret;

	return 0;



out_destroy_policy:

	for_each_cpu(j, policy->real_cpus)
@@ -1606,7 +1603,7 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy, 
out_clear_policy:

	cpumask_clear(policy->cpus);



	goto out_unlock;

	return ret;

}



static int cpufreq_online(unsigned int cpu)
@@ -1754,11 +1751,10 @@ static int cpufreq_offline(unsigned int cpu) 
		return 0;

	}



	down_write(&policy->rwsem);

	guard(cpufreq_policy_write)(policy);



	__cpufreq_offline(cpu, policy);



	up_write(&policy->rwsem);

	return 0;

}
@@ -1775,21 +1771,18 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) 
	if (!policy)

		return;



	down_write(&policy->rwsem);



	scoped_guard(cpufreq_policy_write, policy) {

		if (cpu_online(cpu))

			__cpufreq_offline(cpu, policy);



		remove_cpu_dev_symlink(policy, cpu, dev);



	if (!cpumask_empty(policy->real_cpus)) {

		up_write(&policy->rwsem);

		if (!cpumask_empty(policy->real_cpus))

			return;

	}



		/*

	 * Unregister cpufreq cooling once all the CPUs of the policy are

	 * removed.

		 * Unregister cpufreq cooling once all the CPUs of the policy

		 * are removed.

		 */

		if (cpufreq_thermal_control_enabled(cpufreq_driver)) {

			cpufreq_cooling_unregister(policy->cdev);
@@ -1799,8 +1792,7 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) 
		/* We did light-weight exit earlier, do full tear down now */

		if (cpufreq_driver->offline && cpufreq_driver->exit)

			cpufreq_driver->exit(policy);



	up_write(&policy->rwsem);

	}



	cpufreq_policy_free(policy);

}
@@ -1954,14 +1946,15 @@ unsigned int cpufreq_get(unsigned int cpu) 
	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);

	unsigned int ret_freq = 0;



	if (policy) {

		down_read(&policy->rwsem);

	if (!policy)

		return 0;



	scoped_guard(cpufreq_policy_read, policy) {

		if (cpufreq_driver->get)

			ret_freq = __cpufreq_get(policy);

		up_read(&policy->rwsem);

	}



	cpufreq_cpu_put(policy);

	}



	return ret_freq;

}
@@ -2022,9 +2015,9 @@ void cpufreq_suspend(void) 


	for_each_active_policy(policy) {

		if (has_target()) {

			down_write(&policy->rwsem);

			scoped_guard(cpufreq_policy_write, policy) {

				cpufreq_stop_governor(policy);

			up_write(&policy->rwsem);

			}

		}



		if (cpufreq_driver->suspend && cpufreq_driver->suspend(policy))
@@ -2065,9 +2058,9 @@ void cpufreq_resume(void) 
			pr_err("%s: Failed to resume driver: %s\n", __func__,

				cpufreq_driver->name);

		} else if (has_target()) {

			down_write(&policy->rwsem);

			scoped_guard(cpufreq_policy_write, policy) {

				ret = cpufreq_start_governor(policy);

			up_write(&policy->rwsem);

			}



			if (ret)

				pr_err("%s: Failed to start governor for CPU%u's policy\n",
@@ -2434,15 +2427,9 @@ int cpufreq_driver_target(struct cpufreq_policy *policy, 
			  unsigned int target_freq,

			  unsigned int relation)

{

	int ret;

	guard(cpufreq_policy_write)(policy);



	down_write(&policy->rwsem);



	ret = __cpufreq_driver_target(policy, target_freq, relation);



	up_write(&policy->rwsem);



	return ret;

	return __cpufreq_driver_target(policy, target_freq, relation);

}

EXPORT_SYMBOL_GPL(cpufreq_driver_target);

include/linux/cpufreq.h

+6 −0
Original line number Diff line number Diff line
@@ -170,6 +170,12 @@ struct cpufreq_policy { 
	struct notifier_block nb_max;

};



DEFINE_GUARD(cpufreq_policy_write, struct cpufreq_policy *,

	     down_write(&_T->rwsem), up_write(&_T->rwsem))



DEFINE_GUARD(cpufreq_policy_read, struct cpufreq_policy *,

	     down_read(&_T->rwsem), up_read(&_T->rwsem))



/*

 * Used for passing new cpufreq policy data to the cpufreq driver's ->verify()

 * callback for sanitization.  That callback is only expected to modify the min