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Message-ID: <f3b2dc4d-3d20-4f90-95ce-5d62fc7ef685@arm.com>
Date: Tue, 28 Nov 2023 08:17:32 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Zhang Rui <rui.zhang@...el.com>
Subject: Re: [PATCH v1] thermal: trip: Rework thermal_zone_set_trip() and its
callers
Hi Rafael,
On 11/27/23 19:59, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.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 quilte a bit
s/quilte/quite/
> by moving the majority of logic into thermal_zone_set_trip().
>
> Rework all of the above funtcions to address the above.
s/funtcions/functions/
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/thermal/thermal_core.h | 9 +++++
> drivers/thermal/thermal_sysfs.c | 52 +++++++---------------------------
> drivers/thermal/thermal_trip.c | 61 ++++++++++++++++++++++++++--------------
> include/linux/thermal.h | 3 -
> 4 files changed, 61 insertions(+), 64 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
> @@ -148,42 +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;
>
> - if (!tz->ops->set_trip_temp && !tz->ops->set_trip_hyst && !tz->trips)
> - return -EINVAL;
Here we could bail out when there are no callbacks.
> + if (trip_id < 0 || trip_id >= tz->num_trips)
> + ret = -EINVAL;
>
> - ret = __thermal_zone_get_trip(tz, trip_id, &t);
> + 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;
> + }
But here we don't bail out and go line below
> + trip->temperature = val;
where we modify the actual '&tz->trips[trip_id]'.
Shouldn't be something like the code flow below?
--------------------------------------------8<-----------------------------
if (!tz->ops->set_trip_temp)
goto unlock;
ret = tz->ops->set_trip_temp(tz, trip_id, val);
if (ret)
goto unlock;
trip->temperature = val;
break
----------------------------------->8--------------------------------------
> + 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;
Similar question here.
> + 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);
> -
Surprisingly, nothing outside thermal fwk uses it...
Maybe it's worth to check other functions there.
Other than that, it looks like a good idea.
Regards,
Lukasz
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