	__acquires(&tty->atomic_write_lock)
{
	if (!mutex_trylock(&tty->atomic_write_lock)) {
		if (ndelay)
			return -EAGAIN;
		if (mutex_lock_interruptible(&tty->atomic_write_lock))
			return -ERESTARTSYS;
	}
	return 0;
}
	__acquires(&tty->atomic_write_lock)
{
	if (!mutex_trylock(&tty->atomic_write_lock)) {
		if (ndelay)
			return -EAGAIN;
		if (mutex_lock_interruptible(&tty->atomic_write_lock))
			return -ERESTARTSYS;
	}
	return 0;
}