ACPI: utils: Dynamically determine acpi_handle_list size

Address a long-standing "TBD" comment in the ACPI headers regarding the
number of handles in struct acpi_handle_list.

The number 10, which along with the comment dates back to 2.4.23, seems
like it may have been arbitrarily chosen and isn't sufficient in all
cases [1].

Finally change the code to dynamically determine the size of the handles
table in struct acpi_handle_list and allocate it accordingly.

Update the users of to struct acpi_handle_list to take the additional
dynamic allocation into account.

Link: https://lore.kernel.org/linux-acpi/20230809094451.15473-1-ivan.hu@canonical.com # [1]
Co-developed-by: Vicki Pfau <vi@endrift.com>
Signed-off-by: Vicki Pfau <vi@endrift.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index c303688ead71..42a3df9d625d 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -208,7 +208,7 @@ static bool update_trip_devices(struct acpi_thermal *tz,
 				struct acpi_thermal_trip *acpi_trip,
 				int index, bool compare)
 {
-	struct acpi_handle_list devices;
+	struct acpi_handle_list devices = { 0 };
 	char method[] = "_PSL";
 	acpi_status status;
 
@@ -218,18 +218,21 @@ static bool update_trip_devices(struct acpi_thermal *tz,
 		method[3] = '0' + index;
 	}
 
-	memset(&devices, 0, sizeof(devices));
-
 	status = acpi_evaluate_reference(tz->device->handle, method, NULL, &devices);
 	if (ACPI_FAILURE(status)) {
 		acpi_handle_info(tz->device->handle, "%s evaluation failure\n", method);
 		return false;
 	}
 
-	if (compare && memcmp(&acpi_trip->devices, &devices, sizeof(devices)))
+	if (acpi_handle_list_equal(&acpi_trip->devices, &devices)) {
+		acpi_handle_list_free(&devices);
+		return true;
+	}
+
+	if (compare)
 		ACPI_THERMAL_TRIPS_EXCEPTION(tz, "device");
 
-	memcpy(&acpi_trip->devices, &devices, sizeof(devices));
+	acpi_handle_list_replace(&acpi_trip->devices, &devices);
 	return true;
 }
 
@@ -842,6 +845,17 @@ static void acpi_thermal_check_fn(struct work_struct *work)
 	mutex_unlock(&tz->thermal_check_lock);
 }
 
+static void acpi_thermal_free_thermal_zone(struct acpi_thermal *tz)
+{
+	int i;
+
+	acpi_handle_list_free(&tz->trips.passive.trip.devices);
+	for (i = 0; i < ACPI_THERMAL_MAX_ACTIVE; i++)
+		acpi_handle_list_free(&tz->trips.active[i].trip.devices);
+
+	kfree(tz);
+}
+
 static int acpi_thermal_add(struct acpi_device *device)
 {
 	struct acpi_thermal_trip *acpi_trip;
@@ -968,7 +982,7 @@ flush_wq:
 free_trips:
 	kfree(tz->trip_table);
 free_memory:
-	kfree(tz);
+	acpi_thermal_free_thermal_zone(tz);
 
 	return result;
 }
@@ -988,7 +1002,7 @@ static void acpi_thermal_remove(struct acpi_device *device)
 	flush_workqueue(acpi_thermal_pm_queue);
 	acpi_thermal_unregister_thermal_zone(tz);
 
-	kfree(tz);
+	acpi_thermal_free_thermal_zone(tz);
 }
 
 #ifdef CONFIG_PM_SLEEP