thermal: core: Introduce thermal_instance_delete()

It is not necessary to walk the thermal_instances list in a trip
descriptor under a cooling device lock, so acquire that lock only
for deleting the given thermal instance from the list of thermal
instances in the given cdev.

Moreover, in analogy with the previous change that introduced
thermal_instance_add(), put the code deleting the given thermal
instance from the lists it is on into a separate new function
called thermal_instance_delete().

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Link: https://patch.msgid.link/[email protected]
Reviewed-by: Lukasz Luba <[email protected]>

Author: rafaeljw

drivers/thermal/thermal_core.c

@@ -868,6 +868,17 @@ static int thermal_bind_cdev_to_trip(struct thermal_zone_device *tz,
 	return result;
 }
 
+static void thermal_instance_delete(struct thermal_instance *instance)
+{
+	list_del(&instance->trip_node);
+
+	mutex_lock(&instance->cdev->lock);
+
+	list_del(&instance->cdev_node);
+
+	mutex_unlock(&instance->cdev->lock);
+}
+
 /**
  * thermal_unbind_cdev_from_trip - unbind a cooling device from a thermal zone.
  * @tz:		pointer to a struct thermal_zone_device.
@@ -884,16 +895,12 @@ static void thermal_unbind_cdev_from_trip(struct thermal_zone_device *tz,
 {
 	struct thermal_instance *pos, *next;
 
-	mutex_lock(&cdev->lock);
 	list_for_each_entry_safe(pos, next, &td->thermal_instances, trip_node) {
 		if (pos->cdev == cdev) {
-			list_del(&pos->trip_node);
-			list_del(&pos->cdev_node);
-			mutex_unlock(&cdev->lock);
+			thermal_instance_delete(pos);
 			goto unbind;
 		}
 	}
-	mutex_unlock(&cdev->lock);
 
 	return;