HID: multitouch: Add memory barriers

This fixes broken atomic checks which cause a race between the
release-timer and processing of hid input.

I noticed that contacts were sometimes sticking, even with the "sticky
fingers" quirk enabled. This fixes that problem.

Cc: [email protected]
Fixes: 9609827 ("HID: multitouch: optimize the sticky fingers timer")
Signed-off-by: Andri Yngvason <[email protected]>
Signed-off-by: Benjamin Tissoires <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: any1

drivers/hid/hid-multitouch.c

@@ -1186,7 +1186,7 @@ static void mt_touch_report(struct hid_device *hid,
 	int contact_count = -1;
 
 	/* sticky fingers release in progress, abort */
-	if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
+	if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
 		return;
 
 	scantime = *app->scantime;
@@ -1267,7 +1267,7 @@ static void mt_touch_report(struct hid_device *hid,
 			del_timer(&td->release_timer);
 	}
 
-	clear_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
+	clear_bit_unlock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
 }
 
 static int mt_touch_input_configured(struct hid_device *hdev,
@@ -1699,11 +1699,11 @@ static void mt_expired_timeout(struct timer_list *t)
 	 * An input report came in just before we release the sticky fingers,
 	 * it will take care of the sticky fingers.
 	 */
-	if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
+	if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
 		return;
 	if (test_bit(MT_IO_FLAGS_PENDING_SLOTS, &td->mt_io_flags))
 		mt_release_contacts(hdev);
-	clear_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
+	clear_bit_unlock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags);
 }
 
 static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)