int tty_put_char(struct tty_struct *tty, unsigned char ch)
{
	if (tty->ops->put_char)
		return tty->ops->put_char(tty, ch);
	return tty->ops->write(tty, &ch, 1);
}

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.