Comment 2 for bug 1981765

Reviewed: https://review.opendev.org/c/starlingx/config/+/849905
Committed: https://opendev.org/starlingx/config/commit/462a1cd967f2ae5f55eee080c45c660e7b3f9af7
Submitter: "Zuul (22348)"
Branch: master

commit 462a1cd967f2ae5f55eee080c45c660e7b3f9af7
Author: Steven Webster <email address hidden>
Date: Thu Jul 14 21:04:16 2022 -0400

    Fix bonding interface sysconfig pre-up params

    An issue was noted when attempting to use a bonded interface on
    a management or cluster-host network without an upper VLAN
    interface. The problem turned out to be the following pre-up
    command in the sysconfig file associated with the bond:

    /sbin/modprobe bonding; echo +%s > /sys/class/net/bonding_masters

    The code which programs this command was added in 2019 to fix bug
    (bug 1836969)

    https://opendev.org/starlingx/config/commit/d0ad539f831d9aef7a7d7d653ff0537f47264852

    However, it is noted that today, this command will fail as the bonded
    interface is already created. Trying to add it to the
    bonding_masters list will fail, leaving the interface in a 'down'
    state.

    The reason this code was added was to be able to disable DAD in
    a duplex-direct system, where the duplicate address detection
    would not complete until both hosts were powered on and
    initialized.

    This commit ensures that:

    1. The interface is only added to the bonding_masters
       in a duplex-direct system (in order to be able to
       disable DAD before the interface comes up)
    2. In the case of a duplex-direct system, if the
       interface is already added to the bonding_masters,
       it won't be added again.

    Note:

    The underlying ifup upstream code already accounts for
    the situation that an interface has been added to the
    bonding_masters list, so it is safe for us to explicitly
    add it in a pre-up directive in the case that DAD must
    be disabled.

    Testing:

    1. Ensure the bonding interface (without VLAN) comes up
    2. Ensure in a duplex-direct system that the accept_dad is
       able to be set (regression test bug 1836969)

    Change-Id: I4f712bbbbfa75adfcccbb737df60109db2fef1ee
    Closes-Bug: 1981765
    Signed-off-by: Steven Webster <email address hidden>