[OVS] When cleaning min QoS, queue could be already deleted

[Rodolfo Alonso]

When OVS agent is started and QoS extension is enabled, the minimum bandwidth QoS and Queues are deleted [1]-->[2].

Although is not possible to have a QoS with deleted Queues assigned (a "referential integrity violation" will be risen), a race condition could happen during functional and fullstack tests [3].

While deleting the Queues referred in the Qos register, an exception catch should be added to hide if the Queue is already deleted. In this case there is no need to raise this exception.

[1] https://github.com/openstack/neutron/blob/590002728d4686cb947391911534c4d42f36cfb5/neutron/plugins/ml2/drivers/openvswitch/agent/extension_drivers/qos_driver.py#L57
[2] https://github.com/openstack/neutron/blob/590002728d4686cb947391911534c4d42f36cfb5/neutron/agent/common/ovs_lib.py#L992
[3] http://logs.openstack.org/95/642295/2/check/neutron-fullstack/26d552e/logs/dsvm-fullstack-logs/TestDscpMarkingQoSOvs.test_dscp_marking_packets_openflow-cli_/neutron-openvswitch-agent--2019-03-11--12-30-51-339462.txt.gz#_2019-03-11_12_30_57_450

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/642501

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/642501
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=1813ec74cc583dcbf7097ded938bc94495ce6fed
Submitter: Zuul
Branch: master

commit 1813ec74cc583dcbf7097ded938bc94495ce6fed
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Mon Mar 11 15:43:48 2019 +0000

    Do not rise exception if OVS Queue is not present when being deleted

    In this case, there is no need to raise an exception because the
    Queue is not present anymore in the OVS database. A warning message
    will be logged.

    Change-Id: I836e762bf0703d53f47877b73354948cba70e9c2
    Closes-Bug: #1819477

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 14.0.0.0rc1 release candidate.