static int send_break(struct tty_struct *tty, unsigned int duration)
{
	int retval;

	if (tty->ops->break_ctl == NULL)
		return 0;

	if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
		retval = tty->ops->break_ctl(tty, duration);
	else {
		/* Do the work ourselves */
		if (tty_write_lock(tty, 0) < 0)
			return -EINTR;
		retval = tty->ops->break_ctl(tty, -1);
		if (retval)
			goto out;
		if (!signal_pending(current))
			msleep_interruptible(duration);
		retval = tty->ops->break_ctl(tty, 0);
out:
		tty_write_unlock(tty);
		if (signal_pending(current))
			retval = -EINTR;
	}
	return retval;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.