taglinefilesource code
write_room1883drivers/char/console.cconsole_driver.write_room = con_write_room;
write_room103drivers/char/n_tty.cspace = tty->driver.write_room(tty);
write_room240drivers/char/pty.cpty_driver.write_room = pty_write_room;
write_room2372drivers/char/serial.cserial_driver.write_room = rs_write_room;
write_room130include/linux/tty_driver.hint  (*write_room)(struct tty_struct *tty);