Commit d2278f35 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

thermal: core: Synchronize suspend-prepare and post-suspend actions 



After commit 5a5efdaf ("thermal: core: Resume thermal zones
asynchronously") it is theoretically possible that, if a system suspend
starts immediately after a system resume, thermal_zone_device_resume()
spawned by the thermal PM notifier for one of the thermal zones at the
end of the system resume will run after the PM thermal notifier for the
suspend-prepare action.  If that happens, tz->suspended set by the latter
will be reset by the former which may lead to unexpected consequences.

To avoid that race, synchronize thermal_zone_device_resume() with the
suspend-prepare thermal PM notifier with the help of additional bool
field and completion in struct thermal_zone_device.

Note that this also ensures running __thermal_zone_device_update() at
least once for each thermal zone between system resume and the following
system suspend in case it is needed to start thermal mitigation.

Fixes: 5a5efdaf ("thermal: core: Resume thermal zones asynchronously")
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 83a7eefe

drivers/thermal/thermal_core.c

+21 −0
Original line number Diff line number Diff line
@@ -1397,6 +1397,7 @@ thermal_zone_device_register_with_trips(const char *type, 
	ida_init(&tz->ida);

	mutex_init(&tz->lock);

	init_completion(&tz->removal);

	init_completion(&tz->resume);

	id = ida_alloc(&thermal_tz_ida, GFP_KERNEL);

	if (id < 0) {

		result = id;
@@ -1642,6 +1643,9 @@ static void thermal_zone_device_resume(struct work_struct *work) 
	thermal_zone_device_init(tz);

	__thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);



	complete(&tz->resume);

	tz->resuming = false;



	mutex_unlock(&tz->lock);

}
@@ -1659,6 +1663,20 @@ static int thermal_pm_notify(struct notifier_block *nb, 
		list_for_each_entry(tz, &thermal_tz_list, node) {

			mutex_lock(&tz->lock);



			if (tz->resuming) {

				/*

				 * thermal_zone_device_resume() queued up for

				 * this zone has not acquired the lock yet, so

				 * release it to let the function run and wait

				 * util it has done the work.

				 */

				mutex_unlock(&tz->lock);



				wait_for_completion(&tz->resume);



				mutex_lock(&tz->lock);

			}



			tz->suspended = true;



			mutex_unlock(&tz->lock);
@@ -1676,6 +1694,9 @@ static int thermal_pm_notify(struct notifier_block *nb, 


			cancel_delayed_work(&tz->poll_queue);



			reinit_completion(&tz->resume);

			tz->resuming = true;



			/*

			 * Replace the work function with the resume one, which

			 * will restore the original work function and schedule

drivers/thermal/thermal_core.h

+4 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ struct thermal_governor { 
 * @type:	the thermal zone device type

 * @device:	&struct device for this thermal zone

 * @removal:	removal completion

 * @resume:	resume completion

 * @trip_temp_attrs:	attributes for trip points for sysfs: trip temperature

 * @trip_type_attrs:	attributes for trip points for sysfs: trip type

 * @trip_hyst_attrs:	attributes for trip points for sysfs: trip hysteresis
@@ -89,6 +90,7 @@ struct thermal_governor { 
 * @poll_queue:	delayed work for polling

 * @notify_event: Last notification event

 * @suspended: thermal zone suspend indicator

 * @resuming:	indicates whether or not thermal zone resume is in progress

 * @trips:	array of struct thermal_trip objects

 */

struct thermal_zone_device {
@@ -96,6 +98,7 @@ struct thermal_zone_device { 
	char type[THERMAL_NAME_LENGTH];

	struct device device;

	struct completion removal;

	struct completion resume;

	struct attribute_group trips_attribute_group;

	struct thermal_attr *trip_temp_attrs;

	struct thermal_attr *trip_type_attrs;
@@ -123,6 +126,7 @@ struct thermal_zone_device { 
	struct delayed_work poll_queue;

	enum thermal_notify_event notify_event;

	bool suspended;

	bool resuming;

#ifdef CONFIG_THERMAL_DEBUGFS

	struct thermal_debugfs *debugfs;

#endif