[PATCH v2 0/2] thermal: trip: Rework thermal_zone_set_trip() and its callers

[PATCH v2 0/2] thermal: trip: Rework thermal_zone_set_trip() and its callers

[Rafael J. Wysocki]

Hi Everyone,

This is a second iteration of

https://patchwork.kernel.org/project/linux-pm/patch/4892163.31r3eYUQgx@kreacher/

split into 2 patches, one of which is just a trivial removal of a statement
that has become redundant after recent changes and the other contains the
rest of the original changes.

Thanks!

[PATCH v2 1/2] thermal: trip: Drop a redundant check from thermal_zone_set_trip()

[Rafael J. Wysocki]

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

After recent changes in the thermal framework, a trip points array is
required for registering a thermal zone that is not tripless, so the
tz->trips pointer in thermal_zone_set_trip() is never NULL and the
check involving it is redundant.  Drop that check.

No functional impact.

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

New patch in v2.

---
 drivers/thermal/thermal_trip.c |    3 ---
 1 file changed, 3 deletions(-)

Index: linux-pm/drivers/thermal/thermal_trip.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_trip.c
+++ linux-pm/drivers/thermal/thermal_trip.c
@@ -153,9 +153,6 @@ int thermal_zone_set_trip(struct thermal
 	struct thermal_trip t;
 	int ret;
 
-	if (!tz->ops->set_trip_temp && !tz->ops->set_trip_hyst && !tz->trips)
-		return -EINVAL;
-
 	ret = __thermal_zone_get_trip(tz, trip_id, &t);
 	if (ret)
 		return ret;

[PATCH v2 2/2] thermal: trip: Rework thermal_zone_set_trip() and its callers

[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, some checks done by them both need not go under the thermal
zone lock and code duplication between them can be reduced quite a bit
by moving the majority of logic into thermal_zone_set_trip().

Rework all of the above functions to address the above.

No intentional functional impact.

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

v1 -> v2:
   * Fix 2 typos in the changelog (Lukasz).
   * Split one change into the [1/2].

---
 drivers/thermal/thermal_core.h  |    9 ++++++
 drivers/thermal/thermal_sysfs.c |   52 ++++++++--------------------------
 drivers/thermal/thermal_trip.c  |   60 +++++++++++++++++++++++++++-------------
 include/linux/thermal.h         |    3 --
 4 files changed, 62 insertions(+), 62 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.h
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.h
+++ linux-pm/drivers/thermal/thermal_core.h
@@ -122,6 +122,15 @@ void __thermal_zone_device_update(struct
 void __thermal_zone_set_trips(struct thermal_zone_device *tz);
 int __thermal_zone_get_trip(struct thermal_zone_device *tz, int trip_id,
 			    struct thermal_trip *trip);
+
+enum thermal_set_trip_target {
+	THERMAL_TRIP_SET_TEMP,
+	THERMAL_TRIP_SET_HYST,
+};
+
+int thermal_zone_set_trip(struct thermal_zone_device *tz, int trip_id,
+			  enum thermal_set_trip_target what, const char *buf);
+
 int thermal_zone_trip_id(struct thermal_zone_device *tz,
 			 const struct thermal_trip *trip);
 int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp);
Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -120,31 +120,17 @@ 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;
-	int trip_id, ret;
+	int trip_id;
+	int ret;
+
+	if (!device_is_registered(dev))
+		return -ENODEV;
 
 	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);
-	if (ret)
-		goto unlock;
-
-	ret = kstrtoint(buf, 10, &trip.temperature);
-	if (ret)
-		goto unlock;
+	ret = thermal_zone_set_trip(tz, trip_id, THERMAL_TRIP_SET_TEMP, buf);
 
-	ret = thermal_zone_set_trip(tz, trip_id, &trip);
-unlock:
-	mutex_unlock(&tz->lock);
-	
 	return ret ? ret : count;
 }
 
@@ -179,30 +165,16 @@ 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;
-	int trip_id, ret;
+	int trip_id;
+	int ret;
+
+	if (!device_is_registered(dev))
+		return -ENODEV;
 
 	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);
-	if (ret)
-		goto unlock;
-
-	ret = kstrtoint(buf, 10, &trip.hysteresis);
-	if (ret)
-		goto unlock;
-
-	ret = thermal_zone_set_trip(tz, trip_id, &trip);
-unlock:
-	mutex_unlock(&tz->lock);
+	ret = thermal_zone_set_trip(tz, trip_id, THERMAL_TRIP_SET_HYST, buf);
 
 	return ret ? ret : count;
 }
Index: linux-pm/drivers/thermal/thermal_trip.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_trip.c
+++ linux-pm/drivers/thermal/thermal_trip.c
@@ -148,39 +148,61 @@ 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)
+			  enum thermal_set_trip_target what, const char *buf)
 {
-	struct thermal_trip t;
-	int ret;
+	struct thermal_trip *trip;
+	int val, ret = 0;
 
-	ret = __thermal_zone_get_trip(tz, trip_id, &t);
+	if (trip_id < 0 || trip_id >= tz->num_trips)
+		ret = -EINVAL;
+
+	ret = kstrtoint(buf, 10, &val);
 	if (ret)
 		return ret;
 
-	if (t.type != trip->type)
-		return -EINVAL;
+	mutex_lock(&tz->lock);
 
-	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;
-	}
+	trip = &tz->trips[trip_id];
 
-	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;
+	switch (what) {
+	case THERMAL_TRIP_SET_TEMP:
+		if (val == trip->temperature)
+			goto unlock;
+
+		if (tz->ops->set_trip_temp) {
+			ret = tz->ops->set_trip_temp(tz, trip_id, val);
+			if (ret)
+				goto unlock;
+		}
+		trip->temperature = val;
+		break;
+
+	case THERMAL_TRIP_SET_HYST:
+		if (val == trip->hysteresis)
+			goto unlock;
+
+		if (tz->ops->set_trip_hyst) {
+			ret = tz->ops->set_trip_hyst(tz, trip_id, val);
+			if (ret)
+				goto unlock;
+		}
+		trip->hysteresis = val;
+		break;
+
+	default:
+		ret = -EINVAL;
+		goto unlock;
 	}
 
-	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;
+unlock:
+	mutex_unlock(&tz->lock);
+
+	return ret;
 }
 
 int thermal_zone_trip_id(struct thermal_zone_device *tz,
Index: linux-pm/include/linux/thermal.h
===================================================================
--- linux-pm.orig/include/linux/thermal.h
+++ linux-pm/include/linux/thermal.h
@@ -283,9 +283,6 @@ int __thermal_zone_get_trip(struct therm
 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);

Re: [PATCH v2 2/2] thermal: trip: Rework thermal_zone_set_trip() and its callers

[Lukasz Luba]

On 11/28/23 13:58, Rafael J. Wysocki wrote:
> 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, some checks done by them both need not go under the thermal
> zone lock and code duplication between them can be reduced quite a bit
> by moving the majority of logic into thermal_zone_set_trip().
> 
> Rework all of the above functions to address the above.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> 
> v1 -> v2:
>     * Fix 2 typos in the changelog (Lukasz).
>     * Split one change into the [1/2].
> 
> ---
>   drivers/thermal/thermal_core.h  |    9 ++++++
>   drivers/thermal/thermal_sysfs.c |   52 ++++++++--------------------------
>   drivers/thermal/thermal_trip.c  |   60 +++++++++++++++++++++++++++-------------
>   include/linux/thermal.h         |    3 --
>   4 files changed, 62 insertions(+), 62 deletions(-)
> 

[snip]

> Index: linux-pm/drivers/thermal/thermal_trip.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_trip.c
> +++ linux-pm/drivers/thermal/thermal_trip.c
> @@ -148,39 +148,61 @@ 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)
> +			  enum thermal_set_trip_target what, const char *buf)
>   {
> -	struct thermal_trip t;
> -	int ret;
> +	struct thermal_trip *trip;
> +	int val, ret = 0;
>   
> -	ret = __thermal_zone_get_trip(tz, trip_id, &t);
> +	if (trip_id < 0 || trip_id >= tz->num_trips)
> +		ret = -EINVAL;

That shouldn't progress forward IMO, but simply 'return -EINVAL;'...

> +
> +	ret = kstrtoint(buf, 10, &val);
>   	if (ret)
>   		return ret;
>   
> -	if (t.type != trip->type)
> -		return -EINVAL;
> +	mutex_lock(&tz->lock);
>   
> -	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;
> -	}
> +	trip = &tz->trips[trip_id];

... because here we might get an issue.

Re: [PATCH v2 1/2] thermal: trip: Drop a redundant check from thermal_zone_set_trip()

[Lukasz Luba]

On 11/28/23 13:56, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> After recent changes in the thermal framework, a trip points array is
> required for registering a thermal zone that is not tripless, so the
> tz->trips pointer in thermal_zone_set_trip() is never NULL and the
> check involving it is redundant.  Drop that check.
> 
> No functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> 
> New patch in v2.
> 
> ---
>   drivers/thermal/thermal_trip.c |    3 ---
>   1 file changed, 3 deletions(-)
> 
> Index: linux-pm/drivers/thermal/thermal_trip.c
> ===================================================================
> --- linux-pm.orig/drivers/thermal/thermal_trip.c
> +++ linux-pm/drivers/thermal/thermal_trip.c
> @@ -153,9 +153,6 @@ int thermal_zone_set_trip(struct thermal
>   	struct thermal_trip t;
>   	int ret;
>   
> -	if (!tz->ops->set_trip_temp && !tz->ops->set_trip_hyst && !tz->trips)
> -		return -EINVAL;
> -
>   	ret = __thermal_zone_get_trip(tz, trip_id, &t);
>   	if (ret)
>   		return ret;
> 
> 
> 

LGTM

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Re: [PATCH v2 2/2] thermal: trip: Rework thermal_zone_set_trip() and its callers

[Rafael J. Wysocki]

On Tue, Nov 28, 2023 at 10:42 PM Lukasz Luba <lukasz.luba@arm.com> wrote:
>
>
>
> On 11/28/23 13:58, Rafael J. Wysocki wrote:
> > 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, some checks done by them both need not go under the thermal
> > zone lock and code duplication between them can be reduced quite a bit
> > by moving the majority of logic into thermal_zone_set_trip().
> >
> > Rework all of the above functions to address the above.
> >
> > No intentional functional impact.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >
> > v1 -> v2:
> >     * Fix 2 typos in the changelog (Lukasz).
> >     * Split one change into the [1/2].
> >
> > ---
> >   drivers/thermal/thermal_core.h  |    9 ++++++
> >   drivers/thermal/thermal_sysfs.c |   52 ++++++++--------------------------
> >   drivers/thermal/thermal_trip.c  |   60 +++++++++++++++++++++++++++-------------
> >   include/linux/thermal.h         |    3 --
> >   4 files changed, 62 insertions(+), 62 deletions(-)
> >
>
> [snip]
>
> > Index: linux-pm/drivers/thermal/thermal_trip.c
> > ===================================================================
> > --- linux-pm.orig/drivers/thermal/thermal_trip.c
> > +++ linux-pm/drivers/thermal/thermal_trip.c
> > @@ -148,39 +148,61 @@ 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)
> > +                       enum thermal_set_trip_target what, const char *buf)
> >   {
> > -     struct thermal_trip t;
> > -     int ret;
> > +     struct thermal_trip *trip;
> > +     int val, ret = 0;
> >
> > -     ret = __thermal_zone_get_trip(tz, trip_id, &t);
> > +     if (trip_id < 0 || trip_id >= tz->num_trips)
> > +             ret = -EINVAL;
>
> That shouldn't progress forward IMO, but simply 'return -EINVAL;'...

Good catch, thank you!

> > +
> > +     ret = kstrtoint(buf, 10, &val);
> >       if (ret)
> >               return ret;
> >
> > -     if (t.type != trip->type)
> > -             return -EINVAL;
> > +     mutex_lock(&tz->lock);
> >
> > -     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;
> > -     }
> > +     trip = &tz->trips[trip_id];
>
> ... because here we might get an issue.

Right.