Comment 1 for bug 1764481

Reviewed: https://review.openstack.org/560703
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=fab032b426e1fa89dc473c61cbf15377fe4aaff3
Submitter: Zuul
Branch: master

commit fab032b426e1fa89dc473c61cbf15377fe4aaff3
Author: Brian Haley <email address hidden>
Date: Wed Apr 11 21:22:23 2018 -0400

    Retry dhcp_release on failures

    Sometimes calls to dhcp_release(6) do not result in removal
    of a lease from the leases file, for example, when the release
    packet is not received by dnsmasq. Trying more than once is
    recommended in this case.

    Instead of blindly trying some number of times, we monitor
    the lease file contents, and retry the dhcp_release(6) call
    when an entry still remains. This is possible since
    dhcp_release(6) is being run from the DHCP server itself.
    We try three times and wait 0.3 seconds between tries.

    We also now check for any stale leases in the leases file
    that are unknown to neutron, also trying to remove them.

    Change-Id: Ic1864f7efbc94db1369ac7f3e2879fda86f95a11
    Closes-bug: #1764481