diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 9426636..1f95e7a 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -113,6 +113,7 @@
 	struct usb_cdc_line_coding line;		/* bits, stop, parity */
 	struct work_struct work;			/* work queue entry for line discipline waking up */
 	struct work_struct waker;
+	wait_queue_head_t drain_wait;			/* close processing */
 	struct tasklet_struct urb_task;                 /* rx processing */
 	spinlock_t throttle_lock;			/* synchronize throtteling and read callback */
 	unsigned int ctrlin;				/* input control lines (DCD, DSR, RI, break, overruns) */