thermal/core: Move the thermal zone lock out of the governors

All the governors throttling ops are taking/releasing the lock at the
beginning and the end of the function.

We can move the mutex to the throttling call site instead.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220805153834.2510142-4-daniel.lezcano@linaro.org

Author: dlezcano

drivers/thermal/gov_bang_bang.c

@@ -96,15 +96,13 @@ static int bang_bang_control(struct thermal_zone_device *tz, int trip)
 {
 	struct thermal_instance *instance;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	thermal_zone_trip_update(tz, trip);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 		thermal_cdev_update(instance->cdev);
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 

drivers/thermal/gov_fair_share.c

@@ -82,7 +82,7 @@ static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 	int total_instance = 0;
 	int cur_trip_level = get_trip_level(tz);
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 		if (instance->trip != trip)
@@ -112,8 +112,6 @@ static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 		mutex_unlock(&cdev->lock);
 	}
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 

drivers/thermal/gov_power_allocator.c

@@ -697,19 +697,19 @@ static void power_allocator_unbind(struct thermal_zone_device *tz)
 
 static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 {
-	int ret = 0;
+	int ret;
 	int switch_on_temp, control_temp;
 	struct power_allocator_params *params = tz->governor_data;
 	bool update;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	/*
 	 * We get called for every trip point but we only need to do
 	 * our calculations once
 	 */
 	if (trip != params->trip_max_desired_temperature)
-		goto out;
+		return 0;
 
 	ret = tz->ops->get_trip_temp(tz, params->trip_switch_on,
 				     &switch_on_temp);
@@ -718,7 +718,7 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 		tz->passive = 0;
 		reset_pid_controller(params);
 		allow_maximum_power(tz, update);
-		goto out;
+		return 0;
 	}
 
 	tz->passive = 1;
@@ -729,14 +729,10 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 		dev_warn(&tz->device,
 			 "Failed to get the maximum desired temperature: %d\n",
 			 ret);
-		goto out;
+		return ret;
 	}
 
-	ret = allocate_power(tz, control_temp);
-
-	mutex_unlock(&tz->lock);
-out:
-	return ret;
+	return allocate_power(tz, control_temp);
 }
 
 static struct thermal_governor thermal_gov_power_allocator = {

drivers/thermal/gov_step_wise.c

@@ -160,15 +160,13 @@ static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 {
 	struct thermal_instance *instance;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	thermal_zone_trip_update(tz, trip);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 		thermal_cdev_update(instance->cdev);
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 

drivers/thermal/thermal_core.c

@@ -311,8 +311,10 @@ static void monitor_thermal_zone(struct thermal_zone_device *tz)
 
 static void handle_non_critical_trips(struct thermal_zone_device *tz, int trip)
 {
+	mutex_lock(&tz->lock);
 	tz->governor ? tz->governor->throttle(tz, trip) :
 		       def_governor->throttle(tz, trip);
+	mutex_unlock(&tz->lock);
 }
 
 void thermal_zone_device_critical(struct thermal_zone_device *tz)