thermal: core: Move thermal zone locking out of bind/unbind functions

Since thermal_bind_cdev_to_trip() and thermal_unbind_cdev_from_trip()
acquire the thermal zone lock, the locking rules for their callers get
complicated.  In particular, the thermal zone lock cannot be acquired
in any code path leading to one of these functions even though it might
be useful to do so.

To address this, remove the thermal zone locking from both these
functions, add lockdep assertions for the thermal zone lock to both
of them and make their callers acquire the thermal zone lock instead.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/3837835.kQq0lBPeGt@rjwysocki.net

1 files changed, 22 insertions, 8 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 0085a8df8523..6980d750e926 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -793,6 +793,7 @@ int thermal_bind_cdev_to_trip(struct thermal_zone_device *tz,
 	int result;
 
 	lockdep_assert_held(&thermal_list_lock);
+	lockdep_assert_held(&tz->lock);
 
 	if (list_empty(&tz->node) || list_empty(&cdev->node))
 		return -EINVAL;
@@ -855,7 +856,6 @@ int thermal_bind_cdev_to_trip(struct thermal_zone_device *tz,
 	if (result)
 		goto remove_trip_file;
 
-	mutex_lock(&tz->lock);
 	mutex_lock(&cdev->lock);
 	list_for_each_entry(pos, &tz->thermal_instances, tz_node)
 		if (pos->trip == trip && pos->cdev == cdev) {
@@ -870,7 +870,6 @@ int thermal_bind_cdev_to_trip(struct thermal_zone_device *tz,
 		thermal_governor_update_tz(tz, THERMAL_TZ_BIND_CDEV);
 	}
 	mutex_unlock(&cdev->lock);
-	mutex_unlock(&tz->lock);
 
 	if (!result)
 		return 0;
@@ -894,11 +893,19 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
 				     unsigned long upper, unsigned long lower,
 				     unsigned int weight)
 {
+	int ret;
+
 	if (trip_index < 0 || trip_index >= tz->num_trips)
 		return -EINVAL;
 
-	return thermal_bind_cdev_to_trip(tz, &tz->trips[trip_index].trip, cdev,
-					 upper, lower, weight);
+	mutex_lock(&tz->lock);
+
+	ret = thermal_bind_cdev_to_trip(tz, &tz->trips[trip_index].trip, cdev,
+					upper, lower, weight);
+
+	mutex_unlock(&tz->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(thermal_zone_bind_cooling_device);
 
@@ -920,7 +927,8 @@ int thermal_unbind_cdev_from_trip(struct thermal_zone_device *tz,
 {
 	struct thermal_instance *pos, *next;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
+
 	mutex_lock(&cdev->lock);
 	list_for_each_entry_safe(pos, next, &tz->thermal_instances, tz_node) {
 		if (pos->trip == trip && pos->cdev == cdev) {
@@ -930,12 +938,10 @@ int thermal_unbind_cdev_from_trip(struct thermal_zone_device *tz,
 			thermal_governor_update_tz(tz, THERMAL_TZ_UNBIND_CDEV);
 
 			mutex_unlock(&cdev->lock);
-			mutex_unlock(&tz->lock);
 			goto unbind;
 		}
 	}
 	mutex_unlock(&cdev->lock);
-	mutex_unlock(&tz->lock);
 
 	return -ENODEV;
 
@@ -953,10 +959,18 @@ int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
 				       int trip_index,
 				       struct thermal_cooling_device *cdev)
 {
+	int ret;
+
 	if (trip_index < 0 || trip_index >= tz->num_trips)
 		return -EINVAL;
 
-	return thermal_unbind_cdev_from_trip(tz, &tz->trips[trip_index].trip, cdev);
+	mutex_lock(&tz->lock);
+
+	ret = thermal_unbind_cdev_from_trip(tz, &tz->trips[trip_index].trip, cdev);
+
+	mutex_unlock(&tz->lock);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(thermal_zone_unbind_cooling_device);