static struct sk_buff * pfkey_xfrm_policy2msg_prep(const struct xfrm_policy *xp)
{
	struct sk_buff *skb;
	int size;

	size = pfkey_xfrm_policy2msg_size(xp);

	skb =  alloc_skb(size + 16, GFP_ATOMIC);
	if (skb == NULL)
		return ERR_PTR(-ENOBUFS);

	return skb;
}