[DHCP] Race condition when creating a network

[Rodolfo Alonso]

When a new network is created, the code [1] first calls the DHCP driver "disable" and then it calls "enable". That sometimes creates a race condition where the namespace is deleted (including the existing DHCP port). This section, that was supposed to be deleted after Zed release, should be removed to avoid the mentioned race condition. For example, for the network "79caa1c4-6e26-49c9-87b3-b8d5add13dbd" in [1], the DHCP agent first deletes the namespace and then tries to create it again, including the DHCP port.

Sometimes that leads to an incomplete state where the DHCP is not present (the DHCP port must be present since the DHCP namespace creation).

[1]https://paste.opendev.org/show/bueaIUiPNoAMuS7xnfmR/
[2]https://paste.opendev.org/show/bYBI4vMG9j4MXGyIpXyA/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/924385

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/924386

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/neutron/+/924385
Committed: https://opendev.org/openstack/neutron/commit/7173bd4e988bcecab2aff4d8aed97af70408cbb5
Submitter: "Zuul (22348)"
Branch: master

commit 7173bd4e988bcecab2aff4d8aed97af70408cbb5
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Thu Jul 18 08:06:33 2024 +0000

    [DHCP] Do not force the DHCP disable call in a network creation

    During a network creation, the code added to support multiple network
    segments [1] was first disabling any existing DHCP namespace (including
    the namespace deletion, the driver removal and the DHCP port deletion)
    and the re-creating it again. The execution of both actions one after
    the other was triggering a race condition where the DHCP namespace was
    left without the DHCP port.

    [1]https://review.opendev.org/c/openstack/neutron/+/840421

    Closes-Bug: #2073464
    Change-Id: Ic688d1c721511868b7bd9943bb679c4cb91b1a60

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Rodolfo Alonso <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/924386
Reason: Tested patch merged

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 25.0.0.0rc1 release candidate.