static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
	int i;
	unsigned char max_level = 0;
	int unix_sock_count = 0;

	if (too_many_unix_fds(current))
		return -ETOOMANYREFS;

	for (i = scm->fp->count - 1; i >= 0; i--) {
		struct sock *sk = unix_get_socket(scm->fp->fp[i]);

		if (sk) {
			unix_sock_count++;
			max_level = max(max_level,
					unix_sk(sk)->recursion_level);
		}
	}
	if (unlikely(max_level > MAX_RECURSION_LEVEL))
		return -ETOOMANYREFS;

	/*
	 * Need to duplicate file references for the sake of garbage
	 * collection.  Otherwise a socket in the fps might become a
	 * candidate for GC while the skb is not yet queued.
	 */
	UNIXCB(skb).fp = scm_fp_dup(scm->fp);
	if (!UNIXCB(skb).fp)
		return -ENOMEM;

	for (i = scm->fp->count - 1; i >= 0; i--)
		unix_inflight(scm->fp->fp[i]);
	return max_level;
}
Unknown