Revert "usb: cdc-wdm: close race between read and workqueue"

commit 1607830 upstream.

This reverts commit 339f836.

It has been found to cause problems in a number of Chromebook devices,
so revert the change until it can be brought back in a safe way.

Link: https://lore.kernel.org/r/385a3519-b45d-48c5-a6fd-a3fdb6bec92f@chromium.org
Reported-by:: Aleksander Morgado <aleksandermj@chromium.org>
Fixes: 339f836 ("usb: cdc-wdm: close race between read and workqueue")
Cc: stable <stable@kernel.org>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/class/cdc-wdm.c

@@ -485,7 +485,6 @@ static ssize_t wdm_write
 static int service_outstanding_interrupt(struct wdm_device *desc)
 {
 	int rv = 0;
-	int used;
 
 	/* submit read urb only if the device is waiting for it */
 	if (!desc->resp_count || !--desc->resp_count)
@@ -500,10 +499,7 @@ static int service_outstanding_interrupt(struct wdm_device *desc)
 		goto out;
 	}
 
-	used = test_and_set_bit(WDM_RESPONDING, &desc->flags);
-	if (used)
-		goto out;
-
+	set_bit(WDM_RESPONDING, &desc->flags);
 	spin_unlock_irq(&desc->iuspin);
 	rv = usb_submit_urb(desc->response, GFP_KERNEL);
 	spin_lock_irq(&desc->iuspin);