sctp: Failover transmitted list on transport delete

Add-IP feature allows users to delete an active transport.  If that
transport has chunks in flight, those chunks need to be moved to another
transport or association may get into unrecoverable state.

Reported-by: Rafael Laufer <rlaufer@cisco.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

net/sctp/associola.c

@@ -584,6 +584,33 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc,
 	    asoc->addip_last_asconf->transport == peer)
 		asoc->addip_last_asconf->transport = NULL;
 
+	/* If we have something on the transmitted list, we have to
+	 * save it off.  The best place is the active path.
+	 */
+	if (!list_empty(&peer->transmitted)) {
+		struct sctp_transport *active = asoc->peer.active_path;
+		struct sctp_chunk *ch;
+
+		/* Reset the transport of each chunk on this list */
+		list_for_each_entry(ch, &peer->transmitted,
+					transmitted_list) {
+			ch->transport = NULL;
+			ch->rtt_in_progress = 0;
+		}
+
+		list_splice_tail_init(&peer->transmitted,
+					&active->transmitted);
+
+		/* Start a T3 timer here in case it wasn't running so
+		 * that these migrated packets have a chance to get
+		 * retrnasmitted.
+		 */
+		if (!timer_pending(&active->T3_rtx_timer))
+			if (!mod_timer(&active->T3_rtx_timer,
+					jiffies + active->rto))
+				sctp_transport_hold(active);
+	}
+
 	asoc->peer.transport_count--;
 
 	sctp_transport_free(peer);