Port status becomes active after updating network/subnet

[yanghongyu]

Pre-conditions:
    Neutron （Pike）,firewall_driver=openvswitch

Reproduction steps:
    1.create vm-A with net-A
    2.shutoff vm-A
    3.show port status of vm-A
    4.update net-A ，change its name to 'net-A-rename'
    5.show port status of vm-A

Description:
    After step 2,we can find the port status of vm-A is down,and at this moment there is no related tap device in br-int.This make sense.
    But,after step 4,the status became active,there is still no tap device,and vm-A still shutoff.This doesn't make any sense.We just change network name.This behavior has no relation to port status .
    According to code,we find that DHCP agent (_dhcp_ready_ports_loop->dhcp_ready_on_ports)will notify neutron server to make ports active each time after network,subnet,port,updated.Why this logic?

Any ideas?

[Li Zhouzhou (lizhouzhou)]

I haven't reproduced this problem. Shutoff(nova stop) vm won't cause port DOWN and tap device was still exsit. So I suspect it may other issues exists.

[yanghongyu (yanghongyu614)]

if firewall_driver choose iptables ,if vm shutoff, tap device will still exist.

[LIU Yulong (dragon889)]

It's an interesting phenomenon, tested in local stable/queens environment.
http://paste.openstack.org/show/753798/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/pike
Review: https://review.opendev.org/669608

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/669793

[OpenStack Infra (hudson-openstack)]

Change abandoned by yanghongyu ([e-mail]) on branch: stable/pike
Review: https://review.opendev.org/669608

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Rodolfo Alonso <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/669793