Patch "thermal: trip: Use READ_ONCE() for lockless access to trip properties" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     thermal-trip-use-read_once-for-lockless-access-to-tr.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c710b0f24ceaf0fa78de7beb66d10095abbaea84
Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Date:   Tue May 28 18:52:13 2024 +0200

    thermal: trip: Use READ_ONCE() for lockless access to trip properties
    
    [ Upstream commit a52641bc6293a24f25956a597e7f32148b0e2bb8 ]
    
    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: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index 88211ccdfbd6..5be6113e7c80 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -150,7 +150,7 @@ 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
@@ -174,7 +174,7 @@ 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);
 	}
@@ -194,7 +194,7 @@ 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
diff --git a/drivers/thermal/thermal_trip.c b/drivers/thermal/thermal_trip.c
index 49e63db68517..b4e7411b2fe7 100644
--- a/drivers/thermal/thermal_trip.c
+++ b/drivers/thermal/thermal_trip.c
@@ -152,7 +152,7 @@ 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) {