#define TTY_PTY_LOCK 16 /* pty private */
#define TTY_NO_WRITE_SPLIT 17 /* Preserve write boundaries to driver */
#define TTY_HUPPED 18 /* Post driver->hangup() */
+#define TTY_HUPPING 19 /* Hangup in progress */
#define TTY_LDISC_HALTED 22 /* Line discipline is halted */
/* Values for tty->flow_change */