[PATCH v4 5/6] thermal: core: Allocate thermal_class statically

Rafael J. Wysocki
2026-04-07T14:10:46Z

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>
---

v3 -> v4: No changes

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
@@ -979,7 +979,11 @@ 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,
@@ -1072,7 +1076,7 @@ __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);
@@ -1095,7 +1099,7 @@ __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);
@@ -1543,7 +1547,7 @@ 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);
@@ -1579,7 +1583,7 @@ 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) {
@@ -1928,21 +1932,11 @@ 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)