[PATCH v3 1/2] thermal: sysfs: Rework the handling of trip point updates

Rafael J. Wysocki
2023-12-04T14:52:56Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Both trip_point_temp_store() and trip_point_hyst_store() use
thermal_zone_set_trip() to update a given trip point, but none of them
actually needs to change more than one field in struct thermal_trip
representing it. However, each of them effectively calls
__thermal_zone_get_trip() twice in a row for the same trip index value,
once directly and once via thermal_zone_set_trip(), which is not
particularly efficient, and the way in which thermal_zone_set_trip()
carries out the update is not particularly straightforward.

Moreover, input processing need not be done under the thermal zone lock
in any of these functions.

Rework trip_point_temp_store() and trip_point_hyst_store() to address
the above, move the part of thermal_zone_set_trip() that is still
useful to a new function called thermal_zone_trip_updated() and drop
the rest of it.

While at it, make trip_point_hyst_store() reject negative hysteresis
values.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v2 -> v3: No changes

v1 -> v2: Still check device_is_registered() under the zone lock

---
drivers/thermal/thermal_core.h | 2 +
drivers/thermal/thermal_sysfs.c | 75 ++++++++++++++++++++++++++++------------
drivers/thermal/thermal_trip.c | 45 ++++--------------------
include/linux/thermal.h | 4 --
4 files changed, 64 insertions(+), 62 deletions(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -78,6 +78,19 @@ mode_store(struct device *dev, struct de
return count;
}

+static int check_thermal_zone_and_trip_id(struct device *dev,
+ struct thermal_zone_device *tz,
+ int trip_id)
+{
+ if (!device_is_registered(dev))
+ return -ENODEV;
+
+ if (trip_id < 0 || trip_id >= tz->num_trips)
+ return -EINVAL;
+
+ return 0;
+}
+
static ssize_t
trip_point_type_show(struct device *dev, struct device_attribute *attr,
char *buf)
@@ -120,28 +133,37 @@ trip_point_temp_store(struct device *dev
const char *buf, size_t count)
{
struct thermal_zone_device *tz = to_thermal_zone(dev);
- struct thermal_trip trip;
+ struct thermal_trip *trip;
int trip_id, ret;
+ int temp;
+
+ ret = kstrtoint(buf, 10, &temp);
+ if (ret)
+ return -EINVAL;

if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)
return -EINVAL;

mutex_lock(&tz->lock);

- if (!device_is_registered(dev)) {
- ret = -ENODEV;
- goto unlock;
- }
-
- ret = __thermal_zone_get_trip(tz, trip_id, &trip);
+ ret = check_thermal_zone_and_trip_id(dev, tz, trip_id);
if (ret)
goto unlock;

- ret = kstrtoint(buf, 10, &trip.temperature);
- if (ret)
- goto unlock;
+ trip = &tz->trips[trip_id];
+
+ if (temp != trip->temperature) {
+ if (tz->ops->set_trip_temp) {
+ ret = tz->ops->set_trip_temp(tz, trip_id, temp);
+ if (ret)
+ goto unlock;
+ }
+
+ trip->temperature = temp;
+
+ thermal_zone_trip_updated(tz, trip);
+ }

- ret = thermal_zone_set_trip(tz, trip_id, &trip);
unlock:
mutex_unlock(&tz->lock);

@@ -179,28 +201,37 @@ trip_point_hyst_store(struct device *dev
const char *buf, size_t count)
{
struct thermal_zone_device *tz = to_thermal_zone(dev);
- struct thermal_trip trip;
+ struct thermal_trip *trip;
int trip_id, ret;
+ int hyst;
+
+ ret = kstrtoint(buf, 10, &hyst);
+ if (ret || hyst < 0)
+ return -EINVAL;

if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)
return -EINVAL;

mutex_lock(&tz->lock);

- if (!device_is_registered(dev)) {
- ret = -ENODEV;
- goto unlock;
- }
-
- ret = __thermal_zone_get_trip(tz, trip_id, &trip);
+ ret = check_thermal_zone_and_trip_id(dev, tz, trip_id);
if (ret)
goto unlock;

- ret = kstrtoint(buf, 10, &trip.hysteresis);
- if (ret)
- goto unlock;
+ trip = &tz->trips[trip_id];
+
+ if (hyst != trip->hysteresis) {
+ if (tz->ops->set_trip_hyst) {
+ ret = tz->ops->set_trip_hyst(tz, trip_id, hyst);
+ if (ret)
+ goto unlock;
+ }
+
+ trip->hysteresis = hyst;
+
+ thermal_zone_trip_updated(tz, trip);
+ }

- ret = thermal_zone_set_trip(tz, trip_id, &trip);
unlock:
mutex_unlock(&tz->lock);

Index: linux-pm/drivers/thermal/thermal_core.h
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.h
+++ linux-pm/drivers/thermal/thermal_core.h
@@ -124,6 +124,8 @@ int __thermal_zone_get_trip(struct therm
struct thermal_trip *trip);
int thermal_zone_trip_id(struct thermal_zone_device *tz,
const struct thermal_trip *trip);
+void thermal_zone_trip_updated(struct thermal_zone_device *tz,
+ const struct thermal_trip *trip);
int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp);

/* sysfs I/F */
Index: linux-pm/drivers/thermal/thermal_trip.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_trip.c
+++ linux-pm/drivers/thermal/thermal_trip.c
@@ -147,42 +147,6 @@ int thermal_zone_get_trip(struct thermal
}
EXPORT_SYMBOL_GPL(thermal_zone_get_trip);

-int thermal_zone_set_trip(struct thermal_zone_device *tz, int trip_id,
- const struct thermal_trip *trip)
-{
- struct thermal_trip t;
- int ret;
-
- ret = __thermal_zone_get_trip(tz, trip_id, &t);
- if (ret)
- return ret;
-
- if (t.type != trip->type)
- return -EINVAL;
-
- if (t.temperature != trip->temperature && tz->ops->set_trip_temp) {
- ret = tz->ops->set_trip_temp(tz, trip_id, trip->temperature);
- if (ret)
- return ret;
- }
-
- if (t.hysteresis != trip->hysteresis && tz->ops->set_trip_hyst) {
- ret = tz->ops->set_trip_hyst(tz, trip_id, trip->hysteresis);
- if (ret)
- return ret;
- }
-
- if (tz->trips && (t.temperature != trip->temperature || t.hysteresis != trip->hysteresis))
- tz->trips[trip_id] = *trip;
-
- thermal_notify_tz_trip_change(tz->id, trip_id, trip->type,
- trip->temperature, trip->hysteresis);
-
- __thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
-
- return 0;
-}
-
int thermal_zone_trip_id(struct thermal_zone_device *tz,
const struct thermal_trip *trip)
{
@@ -192,3 +156,12 @@ int thermal_zone_trip_id(struct thermal_
*/
return trip - tz->trips;
}
+
+void thermal_zone_trip_updated(struct thermal_zone_device *tz,
+ const struct thermal_trip *trip)
+{
+ thermal_notify_tz_trip_change(tz->id, thermal_zone_trip_id(tz, trip),
+ trip->type, trip->temperature,
+ trip->hysteresis);
+ __thermal_zone_device_update(tz, THERMAL_TRIP_CHANGED);
+}
Index: linux-pm/include/linux/thermal.h
===================================================================
--- linux-pm.orig/include/linux/thermal.h
+++ linux-pm/include/linux/thermal.h
@@ -282,10 +282,6 @@ int __thermal_zone_get_trip(struct therm
struct thermal_trip *trip);
int thermal_zone_get_trip(struct thermal_zone_device *tz, int trip_id,
struct thermal_trip *trip);
-
-int thermal_zone_set_trip(struct thermal_zone_device *tz, int trip_id,
- const struct thermal_trip *trip);
-
int for_each_thermal_trip(struct thermal_zone_device *tz,
int (*cb)(struct thermal_trip *, void *),
void *data);