[SCTP] Update retransmission path in a round-robin fashion when a

       retransmission timer expires instead of using the same path
       until the path error count reaches its threshold value.

include/net/sctp/structs.h

@@ -1613,6 +1613,7 @@ void sctp_association_put(sctp_association_t *);
 void sctp_association_hold(sctp_association_t *);
 
 struct sctp_transport *sctp_assoc_choose_shutdown_transport(sctp_association_t *);
+void sctp_assoc_update_retran_path(sctp_association_t *);
 struct sctp_transport *sctp_assoc_lookup_paddr(const sctp_association_t *,
 					  const union sctp_addr *);
 struct sctp_transport *sctp_assoc_add_peer(sctp_association_t *,

net/sctp/associola.c

@@ -887,26 +887,19 @@ void sctp_assoc_update(sctp_association_t *asoc, sctp_association_t *new)
 
 }
 
-/* Choose the transport for sending a shutdown packet.
+/* Update the retran path for sending a retransmitted packet.
  * Round-robin through the active transports, else round-robin
  * through the inactive transports as this is the next best thing
  * we can try.
  */
-struct sctp_transport *sctp_assoc_choose_shutdown_transport(sctp_association_t *asoc)
+void sctp_assoc_update_retran_path(sctp_association_t *asoc)
 {
 	struct sctp_transport *t, *next;
 	struct list_head *head = &asoc->peer.transport_addr_list;
 	struct list_head *pos;
 
-	/* If this is the first time SHUTDOWN is sent, use the active
-	 * path.
-	 */
-	if (!asoc->shutdown_last_sent_to)
-		return asoc->peer.active_path;
-
-	/* Otherwise, find the next transport in a round-robin fashion. */
-
-	t = asoc->shutdown_last_sent_to;
+	/* Find the next transport in a round-robin fashion. */
+	t = asoc->peer.retran_path;
 	pos = &t->transports;
 	next = NULL;
 
@@ -935,13 +928,30 @@ struct sctp_transport *sctp_assoc_choose_shutdown_transport(sctp_association_t *
 		 * other active transports.  If so, use the next
 		 * transport.
 		 */
-		if (t == asoc->shutdown_last_sent_to) {
+		if (t == asoc->peer.retran_path) {
 			t = next;
 			break;
 		}
 	}
 
-	return t;
+	asoc->peer.retran_path = t;
+}
+
+/* Choose the transport for sending a SHUTDOWN packet.  */
+struct sctp_transport *sctp_assoc_choose_shutdown_transport(sctp_association_t *asoc)
+{
+	/* If this is the first time SHUTDOWN is sent, use the active path,
+	 * else use the retran path. If the last SHUTDOWN was sent over the
+	 * retran path, update the retran path and use it. 
+	 */
+	if (!asoc->shutdown_last_sent_to)
+		return asoc->peer.active_path;
+	else {
+		if (asoc->shutdown_last_sent_to == asoc->peer.retran_path)
+			sctp_assoc_update_retran_path(asoc);
+		return asoc->peer.retran_path;
+	}
+
 }
 
 /* Update the association's pmtu and frag_point by going through all the

net/sctp/output.c

@@ -419,6 +419,7 @@ int sctp_packet_transmit(sctp_packet_t *packet)
 	dst = transport->dst;
 	/* The 'obsolete' field of dst is set to 2 when a dst is freed. */
 	if (!dst || (dst->obsolete > 1)) {
+		dst_release(dst);
 		sctp_transport_route(transport, NULL, sctp_sk(sk));
 		sctp_assoc_sync_pmtu(asoc);
 	}

net/sctp/outqueue.c

@@ -321,6 +321,11 @@ void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 	switch(reason) {
 	case SCTP_RETRANSMIT_T3_RTX:
 		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
+		/* Update the retran path if the T3-rtx timer has expired for
+		 * the current retran path.
+		 */
+		if (transport == transport->asoc->peer.retran_path)
+			sctp_assoc_update_retran_path(transport->asoc);
 		break;
 	case SCTP_RETRANSMIT_FAST_RTX:
 		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);

net/sctp/protocol.c

@@ -449,7 +449,6 @@ struct dst_entry *sctp_v4_get_dst(sctp_association_t *asoc,
 
 		if (AF_INET == laddr->a.sa.sa_family) {
 			fl.fl4_src = laddr->a.v4.sin_addr.s_addr;
-			dst = sctp_v4_get_dst(asoc, daddr, &laddr->a);
 			if (!ip_route_output_key(&rt, &fl)) {
 				dst = &rt->u.dst;
 				goto out_unlock;