tw_snd_nxt
snd_basis = tcp_twsk(sk)->tw_snd_nxt;
tcptw->tw_snd_nxt, READ_ONCE(tcptw->tw_rcv_nxt),
u32 seq = tcptw->tw_snd_nxt + 65535 + 2;
u32 isn = tcptw->tw_snd_nxt + 65535 + 2;
tcptw->tw_snd_nxt = tp->snd_nxt;
tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt,