Function tty_alloc_mutex

freebsd/kern/tty.c:1054–1106

}

struct tty *
tty_alloc_mutex(struct ttydevsw *tsw, void *sc, struct mtx *mutex)
{
	struct tty *tp;

	/* Make sure the driver defines all routines. */
#define PATCH_FUNC(x) do {				\
	if (tsw->tsw_ ## x == NULL)			\
		tsw->tsw_ ## x = ttydevsw_def ## x;	\
} while (0)
	PATCH_FUNC(open);
	PATCH_FUNC(close);
	PATCH_FUNC(outwakeup);
	PATCH_FUNC(inwakeup);
	PATCH_FUNC(ioctl);
	PATCH_FUNC(cioctl);
	PATCH_FUNC(param);
	PATCH_FUNC(modem);
	PATCH_FUNC(mmap);
	PATCH_FUNC(pktnotify);
	PATCH_FUNC(free);
	PATCH_FUNC(busy);
#undef PATCH_FUNC

	tp = malloc(sizeof(struct tty) + TTY_PRBUF_SIZE, M_TTY,
	    M_WAITOK | M_ZERO);
	tp->t_prbufsz = TTY_PRBUF_SIZE;
	tp->t_devsw = tsw;
	tp->t_devswsoftc = sc;
	tp->t_flags = tsw->tsw_flags;
	tp->t_drainwait = tty_drainwait;

	tty_init_termios(tp);

	cv_init(&tp->t_inwait, "ttyin");
	cv_init(&tp->t_outwait, "ttyout");
	cv_init(&tp->t_outserwait, "ttyosr");
	cv_init(&tp->t_bgwait, "ttybg");
	cv_init(&tp->t_dcdwait, "ttydcd");

	/* Allow drivers to use a custom mutex to lock the TTY. */
	if (mutex != NULL) {
		tp->t_mtx = mutex;
	} else {
		tp->t_mtx = &tp->t_mtxobj;
		mtx_init(&tp->t_mtxobj, "ttymtx", NULL, MTX_DEF);
	}

	knlist_init_mtx(&tp->t_inpoll.si_note, tp->t_mtx);
	knlist_init_mtx(&tp->t_outpoll.si_note, tp->t_mtx);

	return (tp);
}

static void
tty_dealloc(void *arg)