isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
{
	struct ip_tunnel_prl_entry *p;
	int ok = 1;

	rcu_read_lock();
	p = __ipip6_tunnel_locate_prl(t, iph->saddr);
	if (p) {
		if (p->flags & PRL_DEFAULT)
			skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
		else
			skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
	} else {
		const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;

		if (ipv6_addr_is_isatap(addr6) &&
		    (addr6->s6_addr32[3] == iph->saddr) &&
		    ipv6_chk_prefix(addr6, t->dev))
			skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
		else
			ok = 0;
	}
	rcu_read_unlock();
	return ok;
}

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.