HID: wacom: Fix error path of power-supply initialization

power_supply_unregister() must not be called if power_supply_register() failed.
The wdata->psy.dev pointer may point to invalid memory after a failed
power_supply_register() and hence wacom_remove() will fail while calling
power_supply_unregister().

This changes the wacom_probe function to fail if it cannot register the
power_supply devices. If we would want to keep the previous behaviour we had to
keep some flag about the power_supply state and check it on wacom_remove, but
this seems inappropriate here. Hence, we simply fail, too, if
power_supply_register fails.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-wacom.c

@@ -353,11 +353,7 @@ static int wacom_probe(struct hid_device *hdev,
 	if (ret) {
 		hid_warn(hdev, "can't create sysfs battery attribute, err: %d\n",
 			 ret);
-		/*
-		 * battery attribute is not critical for the tablet, but if it
-		 * failed then there is no need to create ac attribute
-		 */
-		goto move_on;
+		goto err_battery;
 	}
 
 	wdata->ac.properties = wacom_ac_props;
@@ -371,14 +367,8 @@ static int wacom_probe(struct hid_device *hdev,
 	if (ret) {
 		hid_warn(hdev,
 			 "can't create ac battery attribute, err: %d\n", ret);
-		/*
-		 * ac attribute is not critical for the tablet, but if it
-		 * failed then we don't want to battery attribute to exist
-		 */
-		power_supply_unregister(&wdata->battery);
+		goto err_ac;
 	}
-
-move_on:
 #endif
 	hidinput = list_entry(hdev->inputs.next, struct hid_input, list);
 	input = hidinput->input;
@@ -416,6 +406,13 @@ static int wacom_probe(struct hid_device *hdev,
 
 	return 0;
 
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+err_ac:
+	power_supply_unregister(&wdata->battery);
+err_battery:
+	device_remove_file(&hdev->dev, &dev_attr_speed);
+	hid_hw_stop(hdev);
+#endif
 err_free:
 	kfree(wdata);
 	return ret;