Comment 11 for bug 1870352

Reviewed: https://review.opendev.org/751210
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=201c27202c302dc8199b796e0adc41b7b15dd6fb
Submitter: Zuul
Branch: stable/stein

commit 201c27202c302dc8199b796e0adc41b7b15dd6fb
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Thu Apr 2 13:49:19 2020 +0000

    Replace ctype.CDLL by ctypes.PyDLL in linux.ip_lib

    Some linux.ip_lib functions make use of "ctype.CDLL" methods
    (create_netns, remove_netns). Those methods are called inside a
    "privsep" context; that means the function reference and the
    arguments are passed to a privileged context that will execute
    the method.

    "privsep" library makes use of eventlet to implement multitasking.
    If the method executed returns the GIL, nothing guarantees that
    the "eventlet" executor will return it again to this task. This
    could lead to timeouts during the execution of those methods.

    From https://docs.python.org/3.6/library/ctypes.html#ctypes.PyDLL:
      "Instances of this class behave like CDLL instances, except that
       the Python GIL is not released during the function call, and
       after the function execution the Python error flag is checked."

    Change-Id: I36ef9bf59e9c93f50464457a5d9a968738844079
    Closes-Bug: #1870352
    (cherry picked from commit 306280813f34f8bbe384ae5bea67f0f66e316b61)