+ if (!acm)
+ return;
+ if (tty_port_close_start(&acm->port, tty, filp) == 0) {
+ mutex_lock(&open_mutex);
+ if (!acm->dev) {
+ tty_port_tty_set(&acm->port, NULL);
+ acm_tty_unregister(acm);
+ tty->driver_data = NULL;
+ }
+ mutex_unlock(&open_mutex);