Comment 6 for bug 1466663

Reviewed: https://review.openstack.org/205373
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=1a1cc3d44b1bcebb06b403838b670238ec584ca3
Submitter: Jenkins
Branch: stable/kilo

commit 1a1cc3d44b1bcebb06b403838b670238ec584ca3
Author: sridhargaddam <email address hidden>
Date: Fri Jun 19 16:17:01 2015 +0000

    Fix race condition by using lock on enable_radvd

    For an HA Router, radvd is spawned only in the Master Node.
    KeepalivedStateChangeHandler after receiving the state notification
    on the unix domain socket, would either enable/disable the radvd
    process depending on the state of the HA Router. In parallel, if
    there is a request to add an interface to the router, router.process()
    would try to enable radvd in parallel. So there is a possible race
    condition as two threads try to enable radvd in parallel. This patch
    uses appropriate locking mechanism to prevent this race condition.

    Closes-Bug: #1466663
    Change-Id: I40df78cc57fcde5512336d9dfef88b3b06a69bcb
    (cherry picked from commit 27503dad33bb045ac840f13a3e5fc0a5b603abb1)