[PATCH v2 0/2] thermal: sysfs: Simplifications of trip point attribute callbacks

[PATCH v2 0/2] thermal: sysfs: Simplifications of trip point attribute callbacks

[Rafael J. Wysocki]

Hi,

This is the second iteration of

https://lore.kernel.org/linux-pm/5754079.DvuYhMxLoT@kreacher/

which is more careful about locking removals.

The first patch reworks the _store callbacks of the trip point
sysfs attributes, and the second one updates their _show callbacks.

Please refer to the individual patch changelogs for details.

Thanks!

[PATCH v2 0/2] thermal: sysfs: Rework the handling of trip point updates

[Rafael J. Wysocki]

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>
---
 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);

[PATCH v2 2/2] thermal: sysfs: Rework the reading of trip point attributes

[Rafael J. Wysocki]

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

Rework the _show() callback functions for the trip point temperature,
hysteresis and type attributes to avoid copying the values of struct
thermal_trip fields that they do not use and to make them carry out
validation checks with the help of check_thermal_zone_and_trip_id(),
like the corresponding _store() callback functions.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/thermal/thermal_sysfs.c |   55 ++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -96,25 +96,25 @@ trip_point_type_show(struct device *dev,
 		     char *buf)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip trip;
-	int trip_id, result;
+	enum thermal_trip_type type;
+	int trip_id, ret;
 
 	if (sscanf(attr->attr.name, "trip_point_%d_type", &trip_id) != 1)
 		return -EINVAL;
 
 	mutex_lock(&tz->lock);
 
-	if (device_is_registered(dev))
-		result = __thermal_zone_get_trip(tz, trip_id, &trip);
-	else
-		result = -ENODEV;
+	ret = check_thermal_zone_and_trip_id(dev, tz, trip_id);
+	if (ret) {
+		mutex_unlock(&tz->lock);
+		return ret;
+	}
 
-	mutex_unlock(&tz->lock);
+	type = tz->trips[trip_id].type;
 
-	if (result)
-		return result;
+	mutex_unlock(&tz->lock);
 
-	switch (trip.type) {
+	switch (type) {
 	case THERMAL_TRIP_CRITICAL:
 		return sprintf(buf, "critical\n");
 	case THERMAL_TRIP_HOT:
@@ -175,25 +175,24 @@ trip_point_temp_show(struct device *dev,
 		     char *buf)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip trip;
-	int trip_id, ret;
+	int trip_id, ret, temp;
 
 	if (sscanf(attr->attr.name, "trip_point_%d_temp", &trip_id) != 1)
 		return -EINVAL;
 
 	mutex_lock(&tz->lock);
 
-	if (device_is_registered(dev))
-		ret = __thermal_zone_get_trip(tz, trip_id, &trip);
-	else
-		ret = -ENODEV;
+	ret = check_thermal_zone_and_trip_id(dev, tz, trip_id);
+	if (ret) {
+		mutex_unlock(&tz->lock);
+		return ret;
+	}
 
-	mutex_unlock(&tz->lock);
+	temp = tz->trips[trip_id].temperature;
 
-	if (ret)
-		return ret;
+	mutex_unlock(&tz->lock);
 
-	return sprintf(buf, "%d\n", trip.temperature);
+	return sprintf(buf, "%d\n", temp);
 }
 
 static ssize_t
@@ -243,22 +242,24 @@ trip_point_hyst_show(struct device *dev,
 		     char *buf)
 {
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_trip trip;
-	int trip_id, ret;
+	int trip_id, ret, hyst;
 
 	if (sscanf(attr->attr.name, "trip_point_%d_hyst", &trip_id) != 1)
 		return -EINVAL;
 
 	mutex_lock(&tz->lock);
 
-	if (device_is_registered(dev))
-		ret = __thermal_zone_get_trip(tz, trip_id, &trip);
-	else
-		ret = -ENODEV;
+	ret = check_thermal_zone_and_trip_id(dev, tz, trip_id);
+	if (ret) {
+		mutex_unlock(&tz->lock);
+		return ret;
+	}
+
+	hyst = tz->trips[trip_id].hysteresis;
 
 	mutex_unlock(&tz->lock);
 
-	return ret ? ret : sprintf(buf, "%d\n", trip.hysteresis);
+	return ret ? ret : sprintf(buf, "%d\n", hyst);
 }
 
 static ssize_t