thermal: gov_power_allocator: Add missing NULL pointer check

Commit 0dc23567c206 ("thermal: core: Move lists of thermal instances
to trip descriptors") overlooked the case in which the Power Allocator
governor attempts to bind to a tripless thermal zone and params->trip_max
is NULL in check_power_actors().

No power actors can be found in that case, so check_power_actors() needs
to be made return 0 then to restore its previous behavior.

Fixes: 0dc23567c206 ("thermal: core: Move lists of thermal instances to trip descriptors")
Closes: https://lore.kernel.org/linux-pm/Z0NeGF4ryCe_b5rr@sashalap/
Reported-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/2761105.mvXUDI8C0e@rjwysocki.net

diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index ac6fa6b8f99f001eb8c042c528792e8df640f30a..3b644de3292e2e755c43c79f575be76306a6bd88 100644 (file)
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -588,10 +588,15 @@ static void allow_maximum_power(struct thermal_zone_device *tz)
 static int check_power_actors(struct thermal_zone_device *tz,
                              struct power_allocator_params *params)
 {
-       const struct thermal_trip_desc *td = trip_to_trip_desc(params->trip_max);
+       const struct thermal_trip_desc *td;
        struct thermal_instance *instance;
        int ret = 0;
 
+       if (!params->trip_max)
+               return 0;
+
+       td = trip_to_trip_desc(params->trip_max);
+
        list_for_each_entry(instance, &td->thermal_instances, trip_node) {
                if (!cdev_is_power_actor(instance->cdev)) {
                        dev_warn(&tz->device, "power_allocator: %s is not a power actor\n",