Comment 9 for bug 2034540

Reviewed: https://review.opendev.org/c/openstack/neutron/+/894010
Committed: https://opendev.org/openstack/neutron/commit/272b3ae7189e04ad2d8a6541d0c00c60337e24dc
Submitter: "Zuul (22348)"
Branch: stable/yoga

commit 272b3ae7189e04ad2d8a6541d0c00c60337e24dc
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Wed Sep 6 15:58:31 2023 +0000

    Call the "tc qdisc" command for ingress qdisc without parent

    The "tc qdisc" command to create an ingress qdisc does not require
    to define a parent qdisc [1]. The ingress qdisc "differs from other
    qdiscs in that it does not occupy the root of a device".

    The previous command was replacing the default root egress qdisc:
      root@dev20:~# ip netns exec ns01 tc qdisc show
      qdisc noqueue 0: dev dummy root refcnt 2

    This operation is now not permitted with the new kernel.

    This patch is also changing how the TC funtional tests interact with
    the namespace interface created. Now the interface is set to UP before
    the test starts. That changes the "tc qdisc show" command because now
    the default qdisc (see the aforementioned CLI output) is now present,
    as it should be in a live environment (where the interfaces are UP).

    Closes-Bug: #2034540

    [1]https://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.adv-qdisc.ingress.html

    Conflicts:
        neutron/tests/functional/privileged/agent/linux/test_tc_lib.py

    Change-Id: I2f8130dc3cf3244be2a44a4ecbdbaa9c7f865731
    (cherry picked from commit 8cba9a2ee86cb3b65645674ef315c14cfb261143)
    (cherry picked from commit 37d09f95cd58143d0b2de9586158d3a6dfda800b)