Comment 14 for bug 1953478

Reviewed: https://review.opendev.org/c/openstack/neutron/+/824982
Committed: https://opendev.org/openstack/neutron/commit/1562f9141ba9c90c69c1c851dd9a50c8108ab15f
Submitter: "Zuul (22348)"
Branch: master

commit 1562f9141ba9c90c69c1c851dd9a50c8108ab15f
Author: Slawek Kaplonski <email address hidden>
Date: Mon Jan 17 17:02:07 2022 +0100

    Call enable DHCP only if there are subnets with enabled DHCP in network

    In the configure_dhcp_for_network() method in the DHCP agent, we should
    call "enable" from the DHCP driver, and put ports as dhcp_ready_ports
    only if there are subnets with enabled DHCP service in that network.
    Before this patch it was done for network if there were ANY subnets
    there. That in some rare condition could result in calling enable()
    method from the DHCP driver, and putting ports into dhcp_ready_ports
    set even if there were only subnets with disabled dhcp there.

    That could cause the problem with reporting provisioning block completed
    by the DHCP entity and lead to unexpected transition of the port from
    DOWN to UP state on the server side.

    Related-Bug: 1953478
    Change-Id: I8b2cc04a824cd7996b9ba486f8ef614c92b242d5