[PATCH v1 2/6] thermal: ACPI: Discard trip table after zone registration

Rafael J. Wysocki
2024-02-05T21:21:16Z

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

Because the thermal core creates and uses its own copy of the trips
table passed to thermal_zone_device_register_with_trips(), it is not
necessary to hold on to a local copy of it any more after the given
thermal zone has been registered.

Accordingly, modify the ACPI thermal driver to store the trips table
passed to thermal_zone_device_register_with_trips() in a local variable
which is automatically discarded after the zone registration.

Also make some additional code simplifications unlocked by the above
change.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/thermal.c | 57 +++++++++++++++++--------------------------------
1 file changed, 20 insertions(+), 37 deletions(-)

Index: linux-pm/drivers/acpi/thermal.c
===================================================================
--- linux-pm.orig/drivers/acpi/thermal.c
+++ linux-pm/drivers/acpi/thermal.c
@@ -47,6 +47,8 @@

#define ACPI_THERMAL_TRIP_PASSIVE (-1)

+#define ACPI_THERMAL_MAX_NR_TRIPS (ACPI_THERMAL_MAX_ACTIVE + 3)
+
/*
* This exception is thrown out in two cases:
* 1.An invalid trip point becomes invalid or a valid trip point becomes invalid
@@ -112,7 +114,6 @@ struct acpi_thermal {
unsigned long polling_frequency;
volatile u8 zombie;
struct acpi_thermal_trips trips;
- struct thermal_trip *trip_table;
struct thermal_zone_device *thermal_zone;
int kelvin_offset; /* in millidegrees */
struct work_struct thermal_check_work;
@@ -451,26 +452,19 @@ fail:
return false;
}

-static int acpi_thermal_get_trip_points(struct acpi_thermal *tz)
+static void acpi_thermal_get_trip_points(struct acpi_thermal *tz)
{
- unsigned int count = 0;
int i;

- if (acpi_thermal_init_trip(tz, ACPI_THERMAL_TRIP_PASSIVE))
- count++;
+ acpi_thermal_init_trip(tz, ACPI_THERMAL_TRIP_PASSIVE);

for (i = 0; i < ACPI_THERMAL_MAX_ACTIVE; i++) {
- if (acpi_thermal_init_trip(tz, i))
- count++;
- else
+ if (!acpi_thermal_init_trip(tz, i))
break;
-
}

while (++i < ACPI_THERMAL_MAX_ACTIVE)
tz->trips.active[i].trip.temp_dk = THERMAL_TEMP_INVALID;
-
- return count;
}

/* sys I/F for generic thermal sysfs support */
@@ -662,13 +656,14 @@ static void acpi_thermal_zone_sysfs_remo
}

static int acpi_thermal_register_thermal_zone(struct acpi_thermal *tz,
+ const struct thermal_trip *trip_table,
unsigned int trip_count,
int passive_delay)
{
int result;

tz->thermal_zone = thermal_zone_device_register_with_trips("acpitz",
- tz->trip_table,
+ trip_table,
trip_count,
0, tz,
&acpi_thermal_zone_ops,
@@ -823,10 +818,10 @@ static void acpi_thermal_free_thermal_zo

static int acpi_thermal_add(struct acpi_device *device)
{
+ struct thermal_trip trip_table[ACPI_THERMAL_MAX_NR_TRIPS] = { 0 };
struct acpi_thermal_trip *acpi_trip;
struct thermal_trip *trip;
struct acpi_thermal *tz;
- unsigned int trip_count;
int crit_temp, hot_temp;
int passive_delay = 0;
int result;
@@ -848,21 +843,10 @@ static int acpi_thermal_add(struct acpi_
acpi_thermal_aml_dependency_fix(tz);

/* Get trip points [_CRT, _PSV, etc.] (required). */
- trip_count = acpi_thermal_get_trip_points(tz);
+ acpi_thermal_get_trip_points(tz);

crit_temp = acpi_thermal_get_critical_trip(tz);
- if (crit_temp != THERMAL_TEMP_INVALID)
- trip_count++;
-
hot_temp = acpi_thermal_get_hot_trip(tz);
- if (hot_temp != THERMAL_TEMP_INVALID)
- trip_count++;
-
- if (!trip_count) {
- pr_warn(FW_BUG "No valid trip points!\n");
- result = -ENODEV;
- goto free_memory;
- }

/* Get temperature [_TMP] (required). */
result = acpi_thermal_get_temperature(tz);
@@ -881,13 +865,7 @@ static int acpi_thermal_add(struct acpi_

acpi_thermal_guess_offset(tz, crit_temp);

- trip = kcalloc(trip_count, sizeof(*trip), GFP_KERNEL);
- if (!trip) {
- result = -ENOMEM;
- goto free_memory;
- }
-
- tz->trip_table = trip;
+ trip = trip_table;

if (crit_temp != THERMAL_TEMP_INVALID) {
trip->type = THERMAL_TRIP_CRITICAL;
@@ -923,9 +901,17 @@ static int acpi_thermal_add(struct acpi_
trip++;
}

- result = acpi_thermal_register_thermal_zone(tz, trip_count, passive_delay);
+ if (trip == trip_table) {
+ pr_warn(FW_BUG "No valid trip points!\n");
+ result = -ENODEV;
+ goto free_memory;
+ }
+
+ result = acpi_thermal_register_thermal_zone(tz, trip_table,
+ trip - trip_table,
+ passive_delay);
if (result)
- goto free_trips;
+ goto free_memory;

refcount_set(&tz->thermal_check_count, 3);
mutex_init(&tz->thermal_check_lock);
@@ -944,8 +930,6 @@ static int acpi_thermal_add(struct acpi_
flush_wq:
flush_workqueue(acpi_thermal_pm_queue);
acpi_thermal_unregister_thermal_zone(tz);
-free_trips:
- kfree(tz->trip_table);
free_memory:
acpi_thermal_free_thermal_zone(tz);

@@ -966,7 +950,6 @@ static void acpi_thermal_remove(struct a

flush_workqueue(acpi_thermal_pm_queue);
acpi_thermal_unregister_thermal_zone(tz);
- kfree(tz->trip_table);
acpi_thermal_free_thermal_zone(tz);
}