platform/x86: wmi: Decouple WMI device removal from wmi_block_list

Use device_for_each_child_reverse() to find and unregister WMI devices
belonging to a WMI bus device instead of iterating thru the entire
wmi_block_list.
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20231020211005.38216-6-W_Armin@gmx.deReviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/wmi.c

@@ -1280,19 +1280,6 @@ static int wmi_add_device(struct platform_device *pdev, struct wmi_device *wdev)
 	return device_add(&wdev->dev);
 }
 
-static void wmi_free_devices(struct acpi_device *device)
-{
-	struct wmi_block *wblock, *next;
-
-	/* Delete devices for all the GUIDs */
-	list_for_each_entry_safe(wblock, next, &wmi_block_list, list) {
-		if (wblock->acpi_device == device) {
-			list_del(&wblock->list);
-			device_unregister(&wblock->dev.dev);
-		}
-	}
-}
-
 static bool guid_already_parsed_for_legacy(struct acpi_device *device, const guid_t *guid)
 {
 	struct wmi_block *wblock;
@@ -1487,16 +1474,28 @@ static void acpi_wmi_notify_handler(acpi_handle handle, u32 event,
 		event, 0);
 }
 
+static int wmi_remove_device(struct device *dev, void *data)
+{
+	struct wmi_block *wblock = dev_to_wblock(dev);
+
+	list_del(&wblock->list);
+	device_unregister(dev);
+
+	return 0;
+}
+
 static void acpi_wmi_remove(struct platform_device *device)
 {
 	struct acpi_device *acpi_device = ACPI_COMPANION(&device->dev);
+	struct device *wmi_bus_device = dev_get_drvdata(&device->dev);
 
 	acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
 				   acpi_wmi_notify_handler);
 	acpi_remove_address_space_handler(acpi_device->handle,
 				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
-	wmi_free_devices(acpi_device);
-	device_unregister(dev_get_drvdata(&device->dev));
+
+	device_for_each_child_reverse(wmi_bus_device, NULL, wmi_remove_device);
+	device_unregister(wmi_bus_device);
 }
 
 static int acpi_wmi_probe(struct platform_device *device)