thermal/core: Move the mutex inside the thermal_zone_device_update() function

All the different calls inside the thermal_zone_device_update()
function take the mutex.

The previous changes move the mutex out of the different functions,
like the throttling ops. Now that the mutexes are all at the same
level in the call stack for the thermal_zone_device_update() function,
they can be moved inside this one.

That has the benefit of:

1. Simplify the code by not having a plethora of places where the lock is taken

2. Probably closes more race windows because releasing the lock from
one line to another can give the opportunity to the thermal zone to change
its state in the meantime. For example, the thermal zone can be
enabled right after checking it is disabled.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220805153834.2510142-5-daniel.lezcano@linaro.org

1 files changed, 11 insertions, 21 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index fcac28d28739..481217092cdd 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -297,24 +297,18 @@ static void thermal_zone_device_set_polling(struct thermal_zone_device *tz,
 
 static void monitor_thermal_zone(struct thermal_zone_device *tz)
 {
-	mutex_lock(&tz->lock);
-
 	if (tz->mode != THERMAL_DEVICE_ENABLED)
 		thermal_zone_device_set_polling(tz, 0);
 	else if (tz->passive)
 		thermal_zone_device_set_polling(tz, tz->passive_delay_jiffies);
 	else if (tz->polling_delay_jiffies)
 		thermal_zone_device_set_polling(tz, tz->polling_delay_jiffies);
-
-	mutex_unlock(&tz->lock);
 }
 
 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)
@@ -382,7 +376,7 @@ static void update_temperature(struct thermal_zone_device *tz)
 {
 	int temp, ret;
 
-	ret = thermal_zone_get_temp(tz, &temp);
+	ret = __thermal_zone_get_temp(tz, &temp);
 	if (ret) {
 		if (ret != -EAGAIN)
 			dev_warn(&tz->device,
@@ -391,10 +385,8 @@ static void update_temperature(struct thermal_zone_device *tz)
 		return;
 	}
 
-	mutex_lock(&tz->lock);
 	tz->last_temperature = tz->temperature;
 	tz->temperature = temp;
-	mutex_unlock(&tz->lock);
 
 	trace_thermal_temperature(tz);
 
@@ -457,15 +449,9 @@ EXPORT_SYMBOL_GPL(thermal_zone_device_disable);
 
 int thermal_zone_device_is_enabled(struct thermal_zone_device *tz)
 {
-	enum thermal_device_mode mode;
-
-	mutex_lock(&tz->lock);
-
-	mode = tz->mode;
+	lockdep_assert_held(&tz->lock);
 
-	mutex_unlock(&tz->lock);
-
-	return mode == THERMAL_DEVICE_ENABLED;
+	return tz->mode == THERMAL_DEVICE_ENABLED;
 }
 
 void thermal_zone_device_update(struct thermal_zone_device *tz,
@@ -473,9 +459,6 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 {
 	int count;
 
-	if (!thermal_zone_device_is_enabled(tz))
-		return;
-
 	if (atomic_read(&in_suspend))
 		return;
 
@@ -483,9 +466,14 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 		      "'get_temp' ops set\n", __func__))
 		return;
 
+	mutex_lock(&tz->lock);
+
+	if (!thermal_zone_device_is_enabled(tz))
+		goto out;
+
 	update_temperature(tz);
 
-	thermal_zone_set_trips(tz);
+	__thermal_zone_set_trips(tz);
 
 	tz->notify_event = event;
 
@@ -493,6 +481,8 @@ void thermal_zone_device_update(struct thermal_zone_device *tz,
 		handle_thermal_trip(tz, count);
 
 	monitor_thermal_zone(tz);
+out:
+	mutex_unlock(&tz->lock);
 }
 EXPORT_SYMBOL_GPL(thermal_zone_device_update);