USB: cdc-wdm: call wake_up_all to allow driver to shutdown on device …

…removal

wdm_disconnect() waits for the mutex held by wdm_read() before
calling wake_up_all().  This causes a deadlock, preventing device removal
to complete.  Do the wake_up_all() before we start waiting for the locks.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/cdc-wdm.c

@@ -786,13 +786,13 @@ static void wdm_disconnect(struct usb_interface *intf)
 	/* to terminate pending flushes */
 	clear_bit(WDM_IN_USE, &desc->flags);
 	spin_unlock_irqrestore(&desc->iuspin, flags);
+	wake_up_all(&desc->wait);
 	mutex_lock(&desc->rlock);
 	mutex_lock(&desc->wlock);
 	kill_urbs(desc);
 	cancel_work_sync(&desc->rxwork);
 	mutex_unlock(&desc->wlock);
 	mutex_unlock(&desc->rlock);
-	wake_up_all(&desc->wait);
 	if (!desc->count)
 		cleanup(desc);
 	mutex_unlock(&wdm_mutex);