Comment 12 for bug 1503124

Reviewed: https://review.opencontrail.org/14811
Committed: http://github.org/Juniper/contrail-controller/commit/28043f285a55769195b28a56030fc3d4d91fde61
Submitter: Zuul
Branch: R2.20

commit 28043f285a55769195b28a56030fc3d4d91fde61
Author: Prabhjot Singh Sethi <email address hidden>
Date: Mon Nov 2 11:19:35 2015 +0530

Fix ToR-Agent crash on withdrawing HA stale route

Issue:
------
since the route export operations were done async, it
resulted in releasing the ovsdb route peer due to cleanup
before completion of the route operations, causing invalid
pointer access while withdrawing routes

Fix:
----
on DB notification to KSync, enqueue export event for the
entry to a KSync task workqueue, also hold the state of
KSync entry which assures that entry is held in the state
till operation is complete, allowing route operations to
complete before route peer cleanup.

Conflicts:
 src/vnsw/agent/ovs_tor_agent/ovsdb_client/ha_stale_l2_route.cc
 src/vnsw/agent/ovs_tor_agent/ovsdb_client/ovsdb_entry.h

Closes-Bug: 1503124
Change-Id: I32732ce9e32a6fa8bddd3ee2cc8c0bd783afe945
(cherry picked from commit 734223864ec70ca8e04056e8aae4fc7a1e854c4d)