Comment 6 for bug 1155748

Reviewed: https://review.openstack.org/24569
Committed: http://github.com/openstack/quantum/commit/885cc41ff033a24191e93d40cd39d858e108f1d8
Submitter: Jenkins
Branch: master

commit 885cc41ff033a24191e93d40cd39d858e108f1d8
Author: Aaron Rosen <email address hidden>
Date: Wed Mar 20 18:19:04 2013 -0700

    Fix race condition in dhcp agent

    This patch fixes a race condition that can happen in the dhcp agent when
    a subnet is created and then a host route is then immediately added to that
    subnet following a subnet.update.end notification. The race condition occurs
    in refresh_dhcp_helper() where self.enable_dhcp_helper() gets called twice
    since the first call had not completed self.cache.put(network). This same race
    condition can also occur in the other events so lockutils.synchronized() is
    added to synchronize those code segments as well.

    Fixes bug 1155748

    Change-Id: I2ff52adc3dfebddd6d9c15d5dc79aa65be107179