On Thu, Aug 1, 2024 at 2:15 AM Sasha Levin sashal@kernel.org wrote:
From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ 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@intel.com Signed-off-by: Sasha Levin sashal@kernel.org
This is more of a matter of annotation than practical issue. That's why I haven't even added a Fixes: tag to it.
Whether or not to take it into "stable" is up to you. It certainly is low-risk in any case.
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