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>

drivers/acpi/acpi_lpss.c

@@ -578,6 +578,7 @@ static bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle handle)
 {
 	struct acpi_handle_list dep_devices;
 	acpi_status status;
+	bool ret = false;
 	int i;
 
 	if (!acpi_has_method(adev->handle, "_DEP"))
@@ -591,11 +592,14 @@ static bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle handle)
 	}
 
 	for (i = 0; i < dep_devices.count; i++) {
-		if (dep_devices.handles[i] == handle)
-			return true;
+		if (dep_devices.handles[i] == handle) {
+			ret = true;
+			break;
+		}
 	}
 
-	return false;
+	acpi_handle_list_free(&dep_devices);
+	return ret;
 }
 
 static void acpi_lpss_link_consumer(struct device *dev1,

drivers/acpi/scan.c

@@ -2032,6 +2032,7 @@ static u32 acpi_scan_check_dep(acpi_handle handle, bool check_dep)
 		mutex_unlock(&acpi_dep_list_lock);
 	}
 
+	acpi_handle_list_free(&dep_devices);
 	return count;
 }
 

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

drivers/acpi/utils.c

@@ -370,7 +370,8 @@ acpi_evaluate_reference(acpi_handle handle,
 		goto end;
 	}
 
-	if (package->package.count > ACPI_MAX_HANDLES) {
+	list->handles = kcalloc(package->package.count, sizeof(*list->handles), GFP_KERNEL);
+	if (!list->handles) {
 		kfree(package);
 		return AE_NO_MEMORY;
 	}
@@ -402,7 +403,8 @@ acpi_evaluate_reference(acpi_handle handle,
       end:
 	if (ACPI_FAILURE(status)) {
 		list->count = 0;
-		//kfree(list->handles);
+		kfree(list->handles);
+		list->handles = NULL;
 	}
 
 	kfree(buffer.pointer);
@@ -412,6 +414,61 @@ acpi_evaluate_reference(acpi_handle handle,
 
 EXPORT_SYMBOL(acpi_evaluate_reference);
 
+/**
+ * acpi_handle_list_equal - Check if two ACPI handle lists are the same
+ * @list1: First list to compare.
+ * @list2: Second list to compare.
+ *
+ * Return true if the given ACPI handle lists are of the same size and
+ * contain the same ACPI handles in the same order.  Otherwise, return false.
+ */
+bool acpi_handle_list_equal(struct acpi_handle_list *list1,
+			    struct acpi_handle_list *list2)
+{
+	return list1->count == list2->count &&
+		!memcmp(list1->handles, list2->handles,
+		        list1->count * sizeof(acpi_handle));
+}
+EXPORT_SYMBOL_GPL(acpi_handle_list_equal);
+
+/**
+ * acpi_handle_list_replace - Replace one ACPI handle list with another
+ * @dst: ACPI handle list to replace.
+ * @src: Source ACPI handle list.
+ *
+ * Free the handles table in @dst, move the handles table from @src to @dst,
+ * copy count from @src to @dst and clear @src.
+ */
+void acpi_handle_list_replace(struct acpi_handle_list *dst,
+			      struct acpi_handle_list *src)
+{
+	if (dst->count)
+		kfree(dst->handles);
+
+	dst->count = src->count;
+	dst->handles = src->handles;
+
+	src->handles = NULL;
+	src->count = 0;
+}
+EXPORT_SYMBOL_GPL(acpi_handle_list_replace);
+
+/**
+ * acpi_handle_list_free - Free the handles table in an ACPI handle list
+ * @list: ACPI handle list to free.
+ *
+ * Free the handles table in @list and clear its count field.
+ */
+void acpi_handle_list_free(struct acpi_handle_list *list)
+{
+	if (!list->count)
+		return;
+
+	kfree(list->handles);
+	list->count = 0;
+}
+EXPORT_SYMBOL_GPL(acpi_handle_list_free);
+
 acpi_status
 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 {

drivers/platform/surface/surface_acpi_notify.c

@@ -741,6 +741,7 @@ static bool is_san_consumer(struct platform_device *pdev, acpi_handle handle)
 	struct acpi_handle_list dep_devices;
 	acpi_handle supplier = ACPI_HANDLE(&pdev->dev);
 	acpi_status status;
+	bool ret = false;
 	int i;
 
 	if (!acpi_has_method(handle, "_DEP"))
@@ -753,11 +754,14 @@ static bool is_san_consumer(struct platform_device *pdev, acpi_handle handle)
 	}
 
 	for (i = 0; i < dep_devices.count; i++) {
-		if (dep_devices.handles[i] == supplier)
-			return true;
+		if (dep_devices.handles[i] == supplier) {
+			ret = true;
+			break;
+		}
 	}
 
-	return false;
+	acpi_handle_list_free(&dep_devices);
+	return ret;
 }
 
 static acpi_status san_consumer_setup(acpi_handle handle, u32 lvl,

include/acpi/acpi_bus.h

@@ -12,11 +12,9 @@
 #include <linux/device.h>
 #include <linux/property.h>
 
-/* TBD: Make dynamic */
-#define ACPI_MAX_HANDLES	10
 struct acpi_handle_list {
 	u32 count;
-	acpi_handle handles[ACPI_MAX_HANDLES];
+	acpi_handle* handles;
 };
 
 /* acpi_utils.h */
@@ -32,6 +30,11 @@ acpi_evaluate_reference(acpi_handle handle,
 			acpi_string pathname,
 			struct acpi_object_list *arguments,
 			struct acpi_handle_list *list);
+bool acpi_handle_list_equal(struct acpi_handle_list *list1,
+			    struct acpi_handle_list *list2);
+void acpi_handle_list_replace(struct acpi_handle_list *dst,
+			      struct acpi_handle_list *src);
+void acpi_handle_list_free(struct acpi_handle_list *list);
 acpi_status
 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 		  struct acpi_buffer *status_buf);