sctp: fasthandoff with ASCONF at mobile-node

Fast retransmission after changing the last address
with ASCONF negotiation

Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -1085,6 +1085,7 @@ void sctp_transport_burst_reset(struct sctp_transport *);
 unsigned long sctp_transport_timeout(struct sctp_transport *);
 void sctp_transport_reset(struct sctp_transport *);
 void sctp_transport_update_pmtu(struct sctp_transport *, u32);
+void sctp_transport_immediate_rtx(struct sctp_transport *);
 
 
 /* This is the structure we use to queue packets as they come into

net/sctp/sm_make_chunk.c

@@ -3400,8 +3400,10 @@ int sctp_process_asconf_ack(struct sctp_association *asoc,
 		asconf_len -= length;
 	}
 
-	if (no_err && asoc->src_out_of_asoc_ok)
+	if (no_err && asoc->src_out_of_asoc_ok) {
 		asoc->src_out_of_asoc_ok = 0;
+		sctp_transport_immediate_rtx(asoc->peer.primary_path);
+	}
 
 	/* Free the cached last sent asconf chunk. */
 	list_del_init(&asconf->transmitted_list);

net/sctp/transport.c

@@ -641,3 +641,19 @@ void sctp_transport_reset(struct sctp_transport *t)
 	t->cacc.next_tsn_at_change = 0;
 	t->cacc.cacc_saw_newack = 0;
 }
+
+/* Schedule retransmission on the given transport */
+void sctp_transport_immediate_rtx(struct sctp_transport *t)
+{
+	/* Stop pending T3_rtx_timer */
+	if (timer_pending(&t->T3_rtx_timer)) {
+		(void)del_timer(&t->T3_rtx_timer);
+		sctp_transport_put(t);
+	}
+	sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX);
+	if (!timer_pending(&t->T3_rtx_timer)) {
+		if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto))
+			sctp_transport_hold(t);
+	}
+	return;
+}