sk_dontcopy_end
offsetof(struct sock, sk_dontcopy_end));
unsafe_memcpy(&nsk->sk_dontcopy_end, &osk->sk_dontcopy_end,
prot->obj_size - offsetof(struct sock, sk_dontcopy_end),
unsafe_memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end),