[PATCH v3 5/6] thermal: core: Allocate thermal_class statically

["Rafael J. Wysocki" <rafael@kernel.org>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Define thermal_class as a static structure to simplify thermal_init()
and to simplify thermal class availability checks that will need to
be carried out during the suspend and resume of thermal zones after
subsequent changes.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v2 -> v3:
   * Use static variable thermal_class_unavailable (instead of a function)
     for checking if thermal_class is available.

v1 -> v2:
   * Reorder with respect to the next patch to allow the latter to be simpler
   * Add thermal_class_unavailable() (the next patch uses it too)

---
 drivers/thermal/thermal_core.c |   30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -977,7 +977,11 @@ static void thermal_release(struct devic
 	}
 }
 
-static struct class *thermal_class;
+static const struct class thermal_class = {
+	.name = "thermal",
+	.dev_release = thermal_release,
+};
+static bool thermal_class_unavailable __ro_after_init = true;
 
 static inline
 void print_bind_err_msg(struct thermal_zone_device *tz,
@@ -1070,7 +1074,7 @@ __thermal_cooling_device_register(struct
 	    !ops->set_cur_state)
 		return ERR_PTR(-EINVAL);
 
-	if (!thermal_class)
+	if (thermal_class_unavailable)
 		return ERR_PTR(-ENODEV);
 
 	cdev = kzalloc_obj(*cdev);
@@ -1093,7 +1097,7 @@ __thermal_cooling_device_register(struct
 	cdev->np = np;
 	cdev->ops = ops;
 	cdev->updated = false;
-	cdev->device.class = thermal_class;
+	cdev->device.class = &thermal_class;
 	cdev->devdata = devdata;
 
 	ret = cdev->ops->get_max_state(cdev, &cdev->max_state);
@@ -1541,7 +1545,7 @@ thermal_zone_device_register_with_trips(
 	if (polling_delay && passive_delay > polling_delay)
 		return ERR_PTR(-EINVAL);
 
-	if (!thermal_class)
+	if (thermal_class_unavailable)
 		return ERR_PTR(-ENODEV);
 
 	tz = kzalloc_flex(*tz, trips, num_trips);
@@ -1577,7 +1581,7 @@ thermal_zone_device_register_with_trips(
 	if (!tz->ops.critical)
 		tz->ops.critical = thermal_zone_device_critical;
 
-	tz->device.class = thermal_class;
+	tz->device.class = &thermal_class;
 	tz->devdata = devdata;
 	tz->num_trips = num_trips;
 	for_each_trip_desc(tz, td) {
@@ -1929,21 +1933,11 @@ static int __init thermal_init(void)
 	if (result)
 		goto destroy_workqueue;
 
-	thermal_class = kzalloc_obj(*thermal_class);
-	if (!thermal_class) {
-		result = -ENOMEM;
+	result = class_register(&thermal_class);
+	if (result)
 		goto unregister_governors;
-	}
 
-	thermal_class->name = "thermal";
-	thermal_class->dev_release = thermal_release;
-
-	result = class_register(thermal_class);
-	if (result) {
-		kfree(thermal_class);
-		thermal_class = NULL;
-		goto unregister_governors;
-	}
+	thermal_class_unavailable = false;
 
 	result = register_pm_notifier(&thermal_pm_nb);
 	if (result)