mptcp: do not wait for bare sockets' timeout

commit d4e85922e3e7ef2071f91f65e61629b60f3a9cf4 upstream.

If the peer closes all the existing subflows for a given
mptcp socket and later the application closes it, the current
implementation let it survive until the timewait timeout expires.

While the above is allowed by the protocol specification it
consumes resources for almost no reason and additionally
causes sporadic self-tests failures.

Let's move the mptcp socket to the TCP_CLOSE state when there are
no alive subflows at close time, so that the allocated resources
will be freed immediately.

Fixes: e16163b6e2b7 ("mptcp: refactor shutdown and close")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 47f359dac247b6ce48a7603dda54c5fd2c46e30e..5d05d85242bc6fd0970a0c7e1560b0f0d73586f7 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2726,6 +2726,7 @@ static void mptcp_close(struct sock *sk, long timeout)
 {
        struct mptcp_subflow_context *subflow;
        bool do_cancel_work = false;
+       int subflows_alive = 0;
 
        lock_sock(sk);
        sk->sk_shutdown = SHUTDOWN_MASK;
@@ -2747,11 +2748,19 @@ cleanup:
                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
                bool slow = lock_sock_fast_nested(ssk);
 
+               subflows_alive += ssk->sk_state != TCP_CLOSE;
+
                sock_orphan(ssk);
                unlock_sock_fast(ssk, slow);
        }
        sock_orphan(sk);
 
+       /* all the subflows are closed, only timeout can change the msk
+        * state, let's not keep resources busy for no reasons
+        */
+       if (subflows_alive == 0)
+               inet_sk_state_store(sk, TCP_CLOSE);
+
        sock_hold(sk);
        pr_debug("msk=%p state=%d", sk, sk->sk_state);
        if (sk->sk_state == TCP_CLOSE) {