ovs flows are not readded when ovsdb-server/ovs-vswitchd are restarted.

[Marc Gariépy]

when there ovsdb-server and ovs-vswitchd are restarted, neutron-openvswitch-agent doesn't add the conjunction flows back.

http://paste.openstack.org/show/801819/

when restarting the neutron-openvswitch-agent all the flows are re-added correctly.

plugins/ml2/openvswitch_agent.ini:firewall_driver = openvswitch

i'm currently using Openstack Ussuri

== reproduce with ==
1. spawn a couple vms in your cloud
2. dump the flow : ovs-ofctl dump-flows br-int
3. restart ovsdb-server and ovs-switchd (this happens when pkg are updated also)
4- dump the flow and compare what's missing.

[LIU Yulong (dragon889)]

Confirmed, I could reproduce this bug. After restart the openvswitch (ovs-db and vswitchd), these types of flows lost:
table=82, priority=70,ct_state=+est-rel-rpl,ipv6,reg6=0x3,ipv6_src=[*] actions=conjunction(*,1/2)
table=82, priority=70,ct_state=+new-est,ipv6,reg6=0x3,ipv6_src=[*] actions=conjunction(*,1/2)

table=82, priority=70,ct_state=+est-rel-rpl,ip,reg6=0x3,nw_src=[*] actions=conjunction(*,1/2)
table=82, priority=70,ct_state=+new-est,ip,reg6=0x3,nw_src=[*] actions=conjunction(17,1/2)

[Marc Gariépy (mgariepy)]

This review will fix it for master

https://review.opendev.org/c/openstack/neutron/+/773165

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 15.3.3 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 16.3.1 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 17.1.1 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 18.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron queens-eol release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron rocky-eol release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron stein-eol release.