static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk)
{
	struct sk_filter *fp, *old_fp;

	fp = kmalloc(sizeof(*fp), GFP_KERNEL);
	if (!fp)
		return -ENOMEM;

	fp->prog = prog;

	if (!__sk_filter_charge(sk, fp)) {
		kfree(fp);
		return -ENOMEM;
	}
	refcount_set(&fp->refcnt, 1);

	old_fp = rcu_dereference_protected(sk->sk_filter,
					   lockdep_sock_is_held(sk));
	rcu_assign_pointer(sk->sk_filter, fp);

	if (old_fp)
		sk_filter_uncharge(sk, old_fp);

	return 0;
}
Unknown