sk_rxhash
_sock_rps_record_flow_hash(READ_ONCE(sk->sk_rxhash));
hash = READ_ONCE(sk->sk_rxhash);
if (unlikely(READ_ONCE(sk->sk_rxhash) != skb->hash))
WRITE_ONCE(sk->sk_rxhash, skb->hash);
WRITE_ONCE(sk->sk_rxhash, 0);