mptcp: Only use subflow EOF signaling on fallback connections

The MPTCP state machine handles disconnections on non-fallback connections,
but the mptcp_sock still needs to get notified when fallback subflows
disconnect.

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

net/mptcp/subflow.c

@@ -1159,7 +1159,8 @@ static void subflow_state_change(struct sock *sk)
 	if (mptcp_subflow_data_available(sk))
 		mptcp_data_ready(parent, sk);
 
-	if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
+	if (__mptcp_check_fallback(mptcp_sk(parent)) &&
+	    !(parent->sk_shutdown & RCV_SHUTDOWN) &&
 	    !subflow->rx_eof && subflow_is_done(sk)) {
 		subflow->rx_eof = 1;
 		mptcp_subflow_eof(parent);