HID: wacom: use cleanup.h for wacom_wac_queue_flush() buffer management

Use __free(kfree) cleanup facility for the temporary buffer in
wacom_wac_queue_flush() to simplify error paths and ensure the buffer
is freed automatically when it goes out of scope.

Signed-off-by: Jinmo Yang <jinmo44.yang@gmail.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

Author: omnij

drivers/hid/wacom_sys.c

@@ -72,11 +72,10 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 {
 	while (!kfifo_is_empty(fifo)) {
 		int size = kfifo_peek_len(fifo);
-		u8 *buf;
+		u8 *buf __free(kfree) = kzalloc(size, GFP_ATOMIC);
 		unsigned int count;
 		int err;
 
-		buf = kzalloc(size, GFP_ATOMIC);
 		if (!buf) {
 			kfifo_skip(fifo);
 			continue;
@@ -89,16 +88,13 @@ static void wacom_wac_queue_flush(struct hid_device *hdev,
 			// to flush seems reasonable enough, however.
 			hid_warn(hdev, "%s: removed fifo entry with unexpected size\n",
 				 __func__);
-			kfree(buf);
 			continue;
 		}
 		err = hid_report_raw_event(hdev, HID_INPUT_REPORT, buf, size, size, false);
 		if (err) {
 			hid_warn(hdev, "%s: unable to flush event due to error %d\n",
 				 __func__, err);
 		}
-
-		kfree(buf);
 	}
 }