Fix vrouter agent crash at updateksync

Issue:
------
Flow update on BGP as a service flow, results in inline
delete of forward flow, while update doesnot expect a
renew of deleted flow in update context causing assertion

Fix:
----
while trying to associate flow and reverse flow, we should
not delete reverse of reverse flow, if it is flow itself
also since we will be making it as a short flow since it
will be detached from reverse flow, we don't need an
explicit delete

Adding flow lock for missing delete all flow API

Change-Id: I6929ee4a9c4562ab30dcb6ca9650eb0b1d8c5f2d
Closes-Bug: 1575956
(cherry picked from commit 92e685a)

src/vnsw/agent/pkt/flow_table.cc

@@ -411,6 +411,7 @@ void FlowTable::DeleteAll() {
             reverse_entry = it->second;
             ++it;
         }
+        FLOW_LOCK(entry, reverse_entry, FlowEvent::DELETE_FLOW);
         DeleteUnLocked(true, entry, reverse_entry);
     }
 }
@@ -464,19 +465,6 @@ void FlowTable::UpdateReverseFlow(FlowEntry *flow, FlowEntry *rflow) {
         }
     }
 
-    if (rflow && rflow->is_flags_set(FlowEntry::BgpRouterService)) {
-        //In BGP router service for some reason if tcp connection does not
-        //succeed, then client will try again with new source port and this will
-        //create a new flow. Now there will be two flows - one with old source
-        //port and other with new source port. However both of them will have
-        //same reverse flow as its is nat'd with fabric sip/dip.
-        //To avoid this delete old flow and dont let new flow to be short flow.
-        if (rflow_rev) {
-            DeleteUnLocked(rflow_rev->key(), false);
-            rflow_rev = NULL;
-        }
-    }
-
     if (rflow_rev && (rflow_rev->reverse_flow_entry() == NULL)) {
         rflow_rev->MakeShortFlow(FlowEntry::SHORT_NO_REVERSE_FLOW);
         if (ValidFlowMove(flow, rflow_rev) == false) {