Commit a52641bc authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

thermal: trip: Use READ_ONCE() for lockless access to trip properties 



When accessing trip temperature and hysteresis without locking, it is
better to use READ_ONCE() to prevent compiler optimizations possibly
affecting the read from being applied.

Of course, for the READ_ONCE() to be effective, WRITE_ONCE() needs to
be used when updating their values.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 893bae92

drivers/thermal/thermal_sysfs.c

+3 −3
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ trip_point_temp_show(struct device *dev, struct device_attribute *attr, 
	if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)

		return -EINVAL;



	return sprintf(buf, "%d\n", tz->trips[trip_id].trip.temperature);

	return sprintf(buf, "%d\n", READ_ONCE(tz->trips[trip_id].trip.temperature));

}



static ssize_t
@@ -163,7 +163,7 @@ trip_point_hyst_store(struct device *dev, struct device_attribute *attr, 
	trip = &tz->trips[trip_id].trip;



	if (hyst != trip->hysteresis) {

		trip->hysteresis = hyst;

		WRITE_ONCE(trip->hysteresis, hyst);



		thermal_zone_trip_updated(tz, trip);

	}
@@ -183,7 +183,7 @@ trip_point_hyst_show(struct device *dev, struct device_attribute *attr, 
	if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)

		return -EINVAL;



	return sprintf(buf, "%d\n", tz->trips[trip_id].trip.hysteresis);

	return sprintf(buf, "%d\n", READ_ONCE(tz->trips[trip_id].trip.hysteresis));

}



static ssize_t

drivers/thermal/thermal_trip.c

+1 −1
Original line number Diff line number Diff line
@@ -161,7 +161,7 @@ void thermal_zone_set_trip_temp(struct thermal_zone_device *tz, 
	if (trip->temperature == temp)

		return;



	trip->temperature = temp;

	WRITE_ONCE(trip->temperature, temp);

	thermal_notify_tz_trip_change(tz, trip);



	if (temp == THERMAL_TEMP_INVALID) {