thermal/core/fair share: Lock the thermal zone while looping over instances

commit fef0577 upstream.

The tz->lock must be hold during the looping over the instances in that
thermal zone. This lock was missing in the governor code since the
beginning, so it's hard to point into a particular commit.

CC: [email protected] # 4.4+
Signed-off-by: Lukasz Luba <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: lukaszluba-arm

drivers/thermal/fair_share.c

@@ -94,6 +94,8 @@ 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);
+
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 		if (instance->trip != trip)
 			continue;
@@ -122,6 +124,8 @@ static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 		mutex_unlock(&instance->cdev->lock);
 		thermal_cdev_update(cdev);
 	}
+
+	mutex_unlock(&tz->lock);
 	return 0;
 }