struct mutex mutex;
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 */