From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
[ 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>
---
drivers/thermal/thermal_sysfs.c | 6 +++---
drivers/thermal/thermal_trip.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index 88211ccdfbd62..5be6113e7c80f 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 49e63db685172..b4e7411b2fe74 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) {
--
2.43.0
