unsigned int ack_size;
        bool ret = false;
        bool can_ack;
-       u64 ack_seq;
        u8 tcp_fin;
 
        if (skb) {
        can_ack = true;
        opts->ext_copy.use_ack = 0;
        msk = mptcp_sk(subflow->conn);
-       if (likely(msk && READ_ONCE(msk->can_ack))) {
-               ack_seq = msk->ack_seq;
-       } else if (subflow->can_ack) {
-               mptcp_crypto_key_sha(subflow->remote_key, NULL, &ack_seq);
-               ack_seq++;
-       } else {
-               can_ack = false;
-       }
-
-       if (unlikely(!can_ack)) {
+       if (!READ_ONCE(msk->can_ack)) {
                *size = ALIGN(dss_size, 4);
                return ret;
        }
 
        dss_size += ack_size;
 
-       opts->ext_copy.data_ack = ack_seq;
+       opts->ext_copy.data_ack = msk->ack_seq;
        opts->ext_copy.ack64 = 1;
        opts->ext_copy.use_ack = 1;
 
 
 
        subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 
-       if (subflow->conn && !subflow->conn_finished) {
+       if (!subflow->conn_finished) {
                pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk),
                         subflow->remote_key);
                mptcp_finish_connect(sk);
        if (subflow->data_avail)
                return true;
 
-       if (!subflow->conn)
-               return false;
-
        msk = mptcp_sk(subflow->conn);
        for (;;) {
                u32 map_remaining;
        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
        struct sock *parent = subflow->conn;
 
-       if (!parent || !subflow->mp_capable) {
+       if (!subflow->mp_capable) {
                subflow->tcp_data_ready(sk);
 
-               if (parent)
-                       parent->sk_data_ready(parent);
+               parent->sk_data_ready(parent);
                return;
        }
 
        struct sock *parent = subflow->conn;
 
        sk_stream_write_space(sk);
-       if (parent && sk_stream_is_writeable(sk)) {
+       if (sk_stream_is_writeable(sk)) {
                set_bit(MPTCP_SEND_SPACE, &mptcp_sk(parent)->flags);
                smp_mb__after_atomic();
                /* set SEND_SPACE before sk_stream_write_space clears NOSPACE */
 static void subflow_state_change(struct sock *sk)
 {
        struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
-       struct sock *parent = READ_ONCE(subflow->conn);
+       struct sock *parent = subflow->conn;
 
        __subflow_state_change(sk);
 
         * a fin packet carrying a DSS can be unnoticed if we don't trigger
         * the data available machinery here.
         */
-       if (parent && subflow->mp_capable && mptcp_subflow_data_available(sk))
+       if (subflow->mp_capable && mptcp_subflow_data_available(sk))
                mptcp_data_ready(parent, sk);
 
-       if (parent && !(parent->sk_shutdown & RCV_SHUTDOWN) &&
+       if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
            !subflow->rx_eof && subflow_is_done(sk)) {
                subflow->rx_eof = 1;
                parent->sk_shutdown |= RCV_SHUTDOWN;