-extern void register_winch(int fd, void *device_data);
-extern void register_winch_irq(int fd, int tty_fd, int pid, void *line);
+struct tty_struct;
+extern void register_winch(int fd, struct tty_struct *tty);
+extern void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty);