mptcp: Add helper to process acks of DATA_FIN

After DATA_FIN has been sent, the peer will acknowledge it. An ack of
the relevant MPTCP-level sequence number will update the MPTCP
connection state appropriately.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 51370b6..b335083 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -143,6 +143,14 @@ static void __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
        MPTCP_SKB_CB(skb)->offset = offset;
 }
 
+static void mptcp_stop_timer(struct sock *sk)
+{
+       struct inet_connection_sock *icsk = inet_csk(sk);
+
+       sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
+       mptcp_sk(sk)->timer_ival = 0;
+}
+
 /* both sockets must be locked */
 static bool mptcp_subflow_dsn_valid(const struct mptcp_sock *msk,
                                    struct sock *ssk)
@@ -164,6 +172,42 @@ static bool mptcp_subflow_dsn_valid(const struct mptcp_sock *msk,
        return mptcp_subflow_data_available(ssk);
 }
 
+static void mptcp_check_data_fin_ack(struct sock *sk)
+{
+       struct mptcp_sock *msk = mptcp_sk(sk);
+
+       if (__mptcp_check_fallback(msk))
+               return;
+
+       /* Look for an acknowledged DATA_FIN */
+       if (((1 << sk->sk_state) &
+            (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) &&
+           msk->write_seq == atomic64_read(&msk->snd_una)) {
+               mptcp_stop_timer(sk);
+
+               WRITE_ONCE(msk->snd_data_fin_enable, 0);
+
+               switch (sk->sk_state) {
+               case TCP_FIN_WAIT1:
+                       inet_sk_state_store(sk, TCP_FIN_WAIT2);
+                       sk->sk_state_change(sk);
+                       break;
+               case TCP_CLOSING:
+                       fallthrough;
+               case TCP_LAST_ACK:
+                       inet_sk_state_store(sk, TCP_CLOSE);
+                       sk->sk_state_change(sk);
+                       break;
+               }
+
+               if (sk->sk_shutdown == SHUTDOWN_MASK ||
+                   sk->sk_state == TCP_CLOSE)
+                       sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+               else
+                       sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
+       }
+}
+
 static bool mptcp_pending_data_fin(struct sock *sk, u64 *seq)
 {
        struct mptcp_sock *msk = mptcp_sk(sk);
@@ -222,6 +266,8 @@ static void mptcp_check_data_fin(struct sock *sk)
                WRITE_ONCE(msk->rcv_data_fin, 0);
 
                sk->sk_shutdown |= RCV_SHUTDOWN;
+               smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
+               set_bit(MPTCP_DATA_READY, &msk->flags);
 
                switch (sk->sk_state) {
                case TCP_ESTABLISHED:
@@ -455,14 +501,6 @@ static void mptcp_check_for_eof(struct mptcp_sock *msk)
        }
 }
 
-static void mptcp_stop_timer(struct sock *sk)
-{
-       struct inet_connection_sock *icsk = inet_csk(sk);
-
-       sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
-       mptcp_sk(sk)->timer_ival = 0;
-}
-
 static bool mptcp_ext_cache_refill(struct mptcp_sock *msk)
 {
        const struct sock *sk = (const struct sock *)msk;