** Also affects: nova/kilo
Importance: Undecided
Status: New
** Also affects: nova/liberty
Importance: Undecided
Status: New
** Tags added: kilo-backport-potential liberty-backport-potential
** Changed in: nova
Importance: Undecided => Medium
** Tags added: network
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https://bugs.launchpad.net/bugs/1533876
Title:
plug_vhostuser may fail due to device not found error when setting mtu
Status in OpenStack Compute (nova):
In Progress
Status in OpenStack Compute (nova) kilo series:
New
Status in OpenStack Compute (nova) liberty series:
New
Bug description:
with certain version of iproute2 spawning of vm with vhost-user ports will
fail do to a
device not found error generated by trying to set the mtu on a vhost-user
port us the ip command.
this bug is present in stable/kilo, stable/liberty and master and i would
like to ask that it be back ported if accepted
and fixed in master.
when using vhost-user with ovs-dpdk the vhost-user port is plugged
into ovs by nova using a non atomic call to
linux_net.create_ovs_vif_port to add an ovs port followed by a second
call to linux_net.ovs_set_vhostuser_port_type to update the port type.
https://github.com/openstack/nova/blob/1bf6a8760f0ef226dba927b62d4354e248b984de/nova/virt/libvirt/vif.py#L652-L655
the reuse of the create_ovs_vif_port has an untended concequece of
introducing an error where
the ip tool is invoked to try and set the mtu on the userspace vhost-user
interface which dose not exist
as a kernel netdev.
https://github.com/openstack/nova/blob/1bf6a8760f0ef226dba927b62d4354e248b984de/nova/network/linux_net.py#L1379
this results in the in the call to set_device_mtu throwing an exception as
the ip comand exits with code 1
https://github.com/openstack/nova/blob/1bf6a8760f0ef226dba927b62d4354e248b984de/nova/network/linux_net.py#L1340-L1342
as a result the second function call to ovs_set_vhostuser_port_type
is never maid and the vm fails to boot.
to resolve this issue i would like to introduce a new function to inux_net.py
create_ovs_vhostuser_port which will create the vhostuser port as an atomic
action
and will not set the mtu similar to the impentation in the os-vif vhost-user
driver
https://github.com/jaypipes/vif_plug_vhostuser/blob/8ac30ce32b3e0bae5d2d8f1edc9d64ac2871608e/vif_plug_vhostuser/linux_net.py#L34-L46
an alternitive solution would be to add "1" to the retrun code check here
https://github.com/openstack/nova/blob/master/nova/network/linux_net.py#L1339
or catch the exception here
https://github.com/openstack/nova/blob/1bf6a8760f0ef226dba927b62d4354e248b984de/nova/virt/libvirt/vif.py#L652
however neither solve the underlying cause.
this was observed with kilo openstack on ubuntu 14.04 with ovs-dpdk
deployed with puppet/fule.
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