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

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: stable@vger.kernel.org # 4.4+
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210422153624.6074-2-lukasz.luba@arm.com

diff --git a/drivers/thermal/gov_fair_share.c b/drivers/thermal/gov_fair_share.c
index aaa07180ab482b157ac5c3dc8d7de20038761635..645432ce636594eb22a65ad079d0ae0d0dd03f75 100644 (file)
--- a/drivers/thermal/gov_fair_share.c
+++ b/drivers/thermal/gov_fair_share.c
@@ -82,6 +82,8 @@ 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;
@@ -110,6 +112,8 @@ 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;
 }