sctp: fasthandoff with ASCONF at server-node

Retransmit chunks to newly confirmed destination when ASCONF and
HEARTBEAT negotiation has success with a single-homed peer.
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_sideeffect.c

@@ -666,6 +666,7 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
 				  struct sctp_chunk *chunk)
 {
 	sctp_sender_hb_info_t *hbinfo;
+	int was_unconfirmed = 0;
 
 	/* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of the
 	 * HEARTBEAT should clear the error counter of the destination
@@ -692,9 +693,11 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
 	/* Mark the destination transport address as active if it is not so
 	 * marked.
 	 */
-	if ((t->state == SCTP_INACTIVE) || (t->state == SCTP_UNCONFIRMED))
+	if ((t->state == SCTP_INACTIVE) || (t->state == SCTP_UNCONFIRMED)) {
+		was_unconfirmed = 1;
 		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
 					     SCTP_HEARTBEAT_SUCCESS);
+	}
 
 	/* The receiver of the HEARTBEAT ACK should also perform an
 	 * RTT measurement for that destination transport address
@@ -712,6 +715,9 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
 	/* Update the heartbeat timer.  */
 	if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
 		sctp_transport_hold(t);
+
+	if (was_unconfirmed && asoc->peer.transport_count == 1)
+		sctp_transport_immediate_rtx(t);
 }