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Date: Tue, 16 Jan 2024 10:14:18 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: rafael@...nel.org, rui.zhang@...el.com, lukasz.luba@....com,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@...labora.com
Subject: Re: [RFC PATCH 26/26] thermal: Introduce thermal zones names
On 21/12/2023 13:48, AngeloGioacchino Del Regno wrote:
> Currently thermal zones have a "type" but this is often used, and
> referenced, as a name instead in multiple kernel drivers that are
> either registering a zone or grabbing a thermal zone handle and
> unfortunately this is a kind of abuse/misuse of the thermal zone
> concept of "type".
>
> In order to disambiguate name<->type and to actually provide an
> accepted way of giving a specific name to a thermal zone for both
> platform drivers and devicetree-defined zones, add a new "name"
> member in the main thermal_zone_device structure, and also to the
> thermal_zone_device_params structure which is used to register a
> thermal zone device.
>
> This will enforce the following constraints:
> - Multiple thermal zones may be of the same "type" (no change);
> - A thermal zone may have a *unique* name: trying to register
> a new zone with the same name as an already present one will
> produce a failure;
> ---
> drivers/thermal/thermal_core.c | 34 ++++++++++++++++++++++++++++++---
> drivers/thermal/thermal_of.c | 1 +
> drivers/thermal/thermal_sysfs.c | 9 +++++++++
> drivers/thermal/thermal_trace.h | 17 +++++++++++------
> include/linux/thermal.h | 4 ++++
> 5 files changed, 56 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 9eb0200a85ff..adf2ac8113e1 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1238,8 +1238,8 @@ EXPORT_SYMBOL_GPL(thermal_zone_get_crit_temp);
> struct thermal_zone_device *thermal_zone_device_register(struct thermal_zone_device_params *tzdp)
> {
> struct thermal_zone_device *tz;
> - int id;
> - int result;
> + int id, tz_name_len;
> + int result = 0;
> struct thermal_governor *governor;
>
> if (!tzdp->type || strlen(tzdp->type) == 0) {
> @@ -1248,11 +1248,36 @@ struct thermal_zone_device *thermal_zone_device_register(struct thermal_zone_dev
> }
>
> if (strlen(tzdp->type) >= THERMAL_NAME_LENGTH) {
> - pr_err("Thermal zone name (%s) too long, should be under %d chars\n",
> + pr_err("Thermal zone type (%s) too long, should be under %d chars\n",
> tzdp->type, THERMAL_NAME_LENGTH);
> return ERR_PTR(-EINVAL);
I would keep that as is and do second round of changes to clarify the
usage of ->type
> }
>
> + tz_name_len = tzdp->name ? strlen(tzdp->name) : 0;
I suggest to change to a const char * and no longer limit to
THERMAL_NAME_LENGTH.
> + if (tz_name_len) {
> + struct thermal_zone_device *pos;
> +
> + if (tz_name_len >= THERMAL_NAME_LENGTH) {
> + pr_err("Thermal zone name (%s) too long, should be under %d chars\n",
> + tzdp->name, THERMAL_NAME_LENGTH);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + mutex_lock(&thermal_list_lock);
> + list_for_each_entry(pos, &thermal_tz_list, node)
> + if (!strncasecmp(tzdp->name, pos->name, THERMAL_NAME_LENGTH)) {
> + result = -EEXIST;
> + break;
> + }
> + mutex_unlock(&thermal_list_lock);
> +
> + if (result) {
> + pr_err("Thermal zone name (%s) already exists and must be unique\n",
> + tzdp->name);
> + return ERR_PTR(result);
> + }
Perhaps a lookup function would be more adequate. What about reusing
thermal_zone_get_by_name() and search with tz->name if it is !NULL,
tz->type otherwise ?
> + }
> +
> /*
> * Max trip count can't exceed 31 as the "mask >> num_trips" condition.
> * For example, shifting by 32 will result in compiler warning:
> @@ -1307,6 +1332,9 @@ struct thermal_zone_device *thermal_zone_device_register(struct thermal_zone_dev
> tz->id = id;
> strscpy(tz->type, tzdp->type, sizeof(tz->type));
>
> + if (tz_name_len)
> + strscpy(tz->name, tzdp->name, sizeof(tzdp->name));
> +
> if (!tzdp->ops->critical)
> tzdp->ops->critical = thermal_zone_device_critical;
>
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index 62a903ad649f..eaacc140abeb 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -486,6 +486,7 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
> ret = PTR_ERR(np);
> goto out_kfree_of_ops;
> }
> + tzdp.name = np->name;
> tzdp.type = np->name;
>
> tzdp.trips = thermal_of_trips_init(np, &tzdp.num_trips);
> diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
> index f52af8a3b4b5..f4002fa6caa2 100644
> --- a/drivers/thermal/thermal_sysfs.c
> +++ b/drivers/thermal/thermal_sysfs.c
> @@ -23,6 +23,14 @@
>
> /* sys I/F for thermal zone */
>
> +static ssize_t
> +name_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct thermal_zone_device *tz = to_thermal_zone(dev);
> +
> + return sprintf(buf, "%s\n", tz->name);
> +}
> +
> static ssize_t
> type_show(struct device *dev, struct device_attribute *attr, char *buf)
> {
> @@ -341,6 +349,7 @@ create_s32_tzp_attr(offset);
> * All the attributes created for tzp (create_s32_tzp_attr) also are always
> * present on the sysfs interface.
> */
> +static DEVICE_ATTR_RO(name);
> static DEVICE_ATTR_RO(type);
> static DEVICE_ATTR_RO(temp);
> static DEVICE_ATTR_RW(policy);
> diff --git a/drivers/thermal/thermal_trace.h b/drivers/thermal/thermal_trace.h
> index 459c8ce6cf3b..c9dbae1e3b9e 100644
> --- a/drivers/thermal/thermal_trace.h
> +++ b/drivers/thermal/thermal_trace.h
> @@ -28,6 +28,7 @@ TRACE_EVENT(thermal_temperature,
> TP_ARGS(tz),
>
> TP_STRUCT__entry(
> + __string(thermal_zone_name, tz->name)
> __string(thermal_zone, tz->type)
> __field(int, id)
> __field(int, temp_prev)
> @@ -35,15 +36,16 @@ TRACE_EVENT(thermal_temperature,
> ),
>
> TP_fast_assign(
> + __assign_str(thermal_zone_name, tz->name);
> __assign_str(thermal_zone, tz->type);
> __entry->id = tz->id;
> __entry->temp_prev = tz->last_temperature;
> __entry->temp = tz->temperature;
> ),
>
> - TP_printk("thermal_zone=%s id=%d temp_prev=%d temp=%d",
> - __get_str(thermal_zone), __entry->id, __entry->temp_prev,
> - __entry->temp)
> + TP_printk("thermal_zone=%s name=%s id=%d temp_prev=%d temp=%d",
> + __get_str(thermal_zone), __get_str(thermal_zone_name),
> + __entry->id, __entry->temp_prev, __entry->temp)
> );
>
> TRACE_EVENT(cdev_update,
> @@ -73,6 +75,7 @@ TRACE_EVENT(thermal_zone_trip,
> TP_ARGS(tz, trip, trip_type),
>
> TP_STRUCT__entry(
> + __string(thermal_zone_name, tz->name)
> __string(thermal_zone, tz->type)
> __field(int, id)
> __field(int, trip)
> @@ -80,15 +83,17 @@ TRACE_EVENT(thermal_zone_trip,
> ),
>
> TP_fast_assign(
> + __assign_str(thermal_zone_name, tz->name);
> __assign_str(thermal_zone, tz->type);
> __entry->id = tz->id;
> __entry->trip = trip;
> __entry->trip_type = trip_type;
> ),
>
> - TP_printk("thermal_zone=%s id=%d trip=%d trip_type=%s",
> - __get_str(thermal_zone), __entry->id, __entry->trip,
> - show_tzt_type(__entry->trip_type))
> + TP_printk("thermal_zone=%s name=%s id=%d trip=%d trip_type=%s",
> + __get_str(thermal_zone), __get_str(thermal_zone_name),
> + __entry->id, __entry->trip,
> + show_tzt_type(__entry->trip_type))
> );
For now, I think we can keep the traces as they are and keep passing the
tz->type. Then we can replace tz->type by tz->name without changing the
trace format.
> #ifdef CONFIG_CPU_THERMAL
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 84b62575d93a..a06521eda162 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -115,6 +115,7 @@ struct thermal_cooling_device {
> /**
> * struct thermal_zone_device - structure for a thermal zone
> * @id: unique id number for each thermal zone
> + * @name: name of the thermal zone device
> * @type: the thermal zone device type
> * @device: &struct device for this thermal zone
> * @removal: removal completion
> @@ -155,6 +156,7 @@ struct thermal_cooling_device {
> */
> struct thermal_zone_device {
> int id;
> + char name[THERMAL_NAME_LENGTH];
> char type[THERMAL_NAME_LENGTH];
> struct device device;
> struct completion removal;
> @@ -260,6 +262,7 @@ struct thermal_zone_params {
>
> /**
> * struct thermal_zone_device_params - parameters for a thermal zone device
> + * @name: name of the thermal zone device
> * @type: the thermal zone device type
> * @tzp: thermal zone platform parameters
> * @ops: standard thermal zone device callbacks
> @@ -274,6 +277,7 @@ struct thermal_zone_params {
> * driven systems)
> */
> struct thermal_zone_device_params {
> + const char *name;
> const char *type;
> struct thermal_zone_params tzp;
> struct thermal_zone_device_ops *ops;
--
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