Stale DHCP ports remain in DHCP namespace

[Eugene Nikanorov]

Consider the following case: 2 or more DHCP agents host a network, then for any reason they go offline.
both (or more) DHCP ports become reserved. If then DHCP agents start or revive nearly at the same time, they may fetch different reserved port that they have owned previously.

At the same time, previous DHCP port remains in the namespace and is not getting cleaned up.
As a result it is possible to get two hosts with the same DHCP namespace having a pair of port which duplicate the same ports on other host.

[Tardis Xu (xiaoxubeii)]

Eugene Nikanorovm: Sorry , i click rebase by mistake

[Eugene Nikanorov (enikanorov)]

https://review.openstack.org/#/c/239264

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/239264
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=6ac43c119bff9da93f438d10033b209819a32230
Submitter: Jenkins
Branch: master

commit 6ac43c119bff9da93f438d10033b209819a32230
Author: Eugene Nikanorov <email address hidden>
Date: Sun Oct 25 15:47:38 2015 +0400

    Cleanup dhcp namespace upon dhcp setup.

    In some cases when more than 1 DHCP agents were assigned
    to a network and then they became dead, their DHCP ports
    become reserved. Later, when those agents revive or start
    again, they acquire reserved ports, but it's not guaranteed
    that they get exactly same ports. In such case DHCP agent
    may create interface in the namespaces despite that another
    interface already exist. In such case there will be two
    hosts with dhcp namespaces each containing duplicate ports,
    e.g. one port will be present on two hosts. This breaks
    DHCP.

    Closes-Bug: #1509959
    Change-Id: I34eb1ad5c44dd3528c9910462e26536186e7a4fb

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/245413

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/245413
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=7d1db366bec234e1a12de73874f16cfe6f772b3c
Submitter: Jenkins
Branch: stable/liberty

commit 7d1db366bec234e1a12de73874f16cfe6f772b3c
Author: Eugene Nikanorov <email address hidden>
Date: Sun Oct 25 15:47:38 2015 +0400

    Cleanup dhcp namespace upon dhcp setup.

    In some cases when more than 1 DHCP agents were assigned
    to a network and then they became dead, their DHCP ports
    become reserved. Later, when those agents revive or start
    again, they acquire reserved ports, but it's not guaranteed
    that they get exactly same ports. In such case DHCP agent
    may create interface in the namespaces despite that another
    interface already exist. In such case there will be two
    hosts with dhcp namespaces each containing duplicate ports,
    e.g. one port will be present on two hosts. This breaks
    DHCP.

    Closes-Bug: #1509959
    Change-Id: I34eb1ad5c44dd3528c9910462e26536186e7a4fb
    (cherry picked from commit 6ac43c119bff9da93f438d10033b209819a32230)

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/neutron 8.0.0.0b1 development milestone.

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/neutron 7.0.1 release.