[PATCH v4 2/6] thermal: core: Free thermal zone ID later during removal

Rafael J. Wysocki
2026-04-07T14:10:56Z

The thermal zone removal ordering is different from the thermal zone
registration rollback path ordering and the former is arguably
problematic because freeing a thermal zone ID prematurely may cause
it to be used during the registration of another thermal zone which
may fail as a result.

Prevent that from occurring by changing the thermal zone removal
ordering to reflect the thermal zone registration rollback path
ordering.

Also more the ida_destroy() call from thermal_zone_device_unregister()
to thermal_release() for consistency.

Fixes: b31ef8285b19 ("thermal core: convert ID allocation to IDA")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v3 -> v4:
* Call ida_destroy() in thermal_release() in analogy with the mutex
cleanup

v2 -> v3: New patch

---
drivers/thermal/thermal_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -972,6 +972,7 @@ static void thermal_release(struct devic
tz = to_thermal_zone(dev);
thermal_zone_destroy_device_groups(tz);
thermal_set_governor(tz, NULL);
+ ida_destroy(&tz->ida);
mutex_destroy(&tz->lock);
complete(&tz->removal);
} else if (!strncmp(dev_name(dev), "cooling_device",
@@ -1736,8 +1737,6 @@ void thermal_zone_device_unregister(stru

thermal_thresholds_exit(tz);
thermal_remove_hwmon_sysfs(tz);
- ida_free(&thermal_tz_ida, tz->id);
- ida_destroy(&tz->ida);

device_del(&tz->device);
put_device(&tz->device);
@@ -1745,6 +1744,9 @@ void thermal_zone_device_unregister(stru
thermal_notify_tz_delete(tz);

wait_for_completion(&tz->removal);
+
+ ida_free(&thermal_tz_ida, tz->id);
+
kfree(tz->tzp);
kfree(tz);
}