TTY_THROTTLED
set_bit(TTY_THROTTLED, &tty->flags);
set_bit(TTY_THROTTLED, &tty->flags);
clear_bit(TTY_THROTTLED, &tty->flags);
if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
set_bit(TTY_THROTTLED, &tty->flags);
clear_bit(TTY_THROTTLED, &tty->flags);
if (test_bit(TTY_THROTTLED, &tty->flags) ||
return test_bit(TTY_THROTTLED, &tty->flags);