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

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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@intel.com>
This commit is contained in:
Rafael J. Wysocki 2024-05-28 18:52:13 +02:00
parent 893bae9223
commit a52641bc62
2 changed files with 4 additions and 4 deletions
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6
drivers/thermal/thermal_sysfs.c
View File

@ -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

2
drivers/thermal/thermal_trip.c
View File

@ -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) {