Comment 3 for bug 1217163

Reviewed: https://review.openstack.org/43929
Committed: http://github.com/openstack/nova/commit/7baa5265e36d76e48fdcb50b9e9a6edc45c0475e
Submitter: Jenkins
Branch: master

commit 7baa5265e36d76e48fdcb50b9e9a6edc45c0475e
Author: Matthew Treinish <email address hidden>
Date: Tue Aug 27 12:01:57 2013 -0400

    Fix race when running initialize_gateway_device()

    If multiple calls that result in initialize_gateway_device() being
    run occur at roughly the same time then there is a race between the
    ip route commands being run at the same time. This will cause
    instances to go into an error state. This commit adds a global lock
    to the initialize_gateway_device() method to prevent it from being
    run at the same time to avoid this issue.

    The race condition is not directly testable in unit tests because it
    requires a multithreaded environment to run
    initialize_gateway_device() at the same time. It was uncovered
    with tempest in parallel.

    Fixes bug 1217163

    Change-Id: Ib750381636d1341062928d0abc8d3518e327935e