ovs-ofctl mod-port <bridge> dpdk<x> down crashes OVS DPDK 2.6.1

Issue

ovs-ofctl mod-port dpdk down crashes OVS DPDK 2.6.1

Steps to reproduce:

[root@overcloud-compute-50 ~]# ovs-ofctl mod-port br-link dpdk2 down
[root@overcloud-compute-50 ~]# systemctl status ovs-vswitchd
● ovs-vswitchd.service - Open vSwitch Forwarding Unit
   Loaded: loaded (/usr/lib/systemd/system/ovs-vswitchd.service; static; vendor preset: disabled)
  Drop-In: /etc/systemd/system/ovs-vswitchd.service.d
           └─timeout.conf
   Active: active (running) since Mon 2018-06-18 18:03:02 UTC; 6min ago
  Process: 8153 ExecStop=/usr/share/openvswitch/scripts/ovs-ctl --no-ovsdb-server stop (code=exited, status=0/SUCCESS)
  Process: 8268 ExecStart=/usr/share/openvswitch/scripts/ovs-ctl --no-ovsdb-server --no-monitor --system-id=random start $OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 8294 (ovs-vswitchd)
   CGroup: /system.slice/ovs-vswitchd.service
           └─8294 ovs-vswitchd unix:/var/run/openvswitch/db.sock -vconsole:emer -vsyslog:err -vfile:info --mlockall --no-chdir --log-file=/var/log/openvswitch/ovs-vswitchd.log --pidfile=/var/run/openvswitch/ovs-v...

Jun 18 18:02:58 overcloud-compute-50 ovs-vswitchd[8294]: PMD: i40e_pf_config_rss(): Max of contiguous 8 PF queues are configured
Jun 18 18:02:58 overcloud-compute-50 ovs-ctl[8268]: PMD: i40e_pf_config_rss(): Max of contiguous 1 PF queues are configured
Jun 18 18:02:58 overcloud-compute-50 ovs-vswitchd[8294]: PMD: i40e_pf_config_rss(): Max of contiguous 1 PF queues are configured
Jun 18 18:02:59 overcloud-compute-50 ovs-ctl[8268]: PMD: i40e_pf_get_vsi_by_qindex(): queue_idx out of range. VMDQ configured?
Jun 18 18:02:59 overcloud-compute-50 ovs-vswitchd[8294]: PMD: i40e_pf_get_vsi_by_qindex(): queue_idx out of range. VMDQ configured?
Jun 18 18:02:59 overcloud-compute-50 ovs-ctl[8268]: PMD: i40e_pf_config_rss(): Max of contiguous 8 PF queues are configured
Jun 18 18:02:59 overcloud-compute-50 ovs-vswitchd[8294]: PMD: i40e_pf_config_rss(): Max of contiguous 8 PF queues are configured
Jun 18 18:03:02 overcloud-compute-50 ovs-ctl[8268]: [  OK  ]
Jun 18 18:03:02 overcloud-compute-50 ovs-ctl[8268]: Enabling remote OVSDB managers [  OK  ]
Jun 18 18:03:02 overcloud-compute-50 systemd[1]: Started Open vSwitch Forwarding Unit.
[root@overcloud-compute-50 ~]# ovs-vsctl list-ifaces br-link-b
dpdk4
dpdk5
phy-br-link-b
[root@overcloud-compute-50 ~]# ovs-vsctl list-ifaces br-link
dpdk2
dpdk3
phy-br-link
[root@overcloud-compute-50 ~]# ovs-appctl bond/show dpdkbond0
---- dpdkbond0 ----
bond_mode: active-backup
bond may use recirculation: no, Recirc-ID : -1
bond-hash-basis: 0
updelay: 0 ms
downdelay: 0 ms
lacp_status: off
active slave mac: aa:bb:cc:2c:e7:42(dpdk1)

slave dpdk0: enabled
    may_enable: true

slave dpdk1: enabled
    active slave
    may_enable: true

[root@overcloud-compute-50 ~]# ovs-appctl bond/show dpdkbond1
---- dpdkbond1 ----
bond_mode: active-backup
bond may use recirculation: no, Recirc-ID : -1
bond-hash-basis: 0
updelay: 0 ms
downdelay: 0 ms
lacp_status: off
active slave mac: aa:bb:cc:2c:ef:e2(dpdk3)

slave dpdk2: disabled
    may_enable: false

slave dpdk3: enabled
    active slave
    may_enable: true

[root@overcloud-compute-50 ~]# ovs-ofctl mod-port br-link dpdk2 up
[root@overcloud-compute-50 ~]# ovs-appctl bond/show dpdkbond1
---- dpdkbond1 ----
bond_mode: active-backup
bond may use recirculation: no, Recirc-ID : -1
bond-hash-basis: 0
updelay: 0 ms
downdelay: 0 ms
lacp_status: off
active slave mac: aa:bb:cc:2c:ef:e2(dpdk3)

slave dpdk2: enabled
    may_enable: true

slave dpdk3: enabled
    active slave
    may_enable: true

[root@overcloud-compute-50 ~]# ovs-ofctl mod-port br-link dpdk3 down
[root@overcloud-compute-50 ~]# ovs-appctl bond/show dpdkbond1
---- dpdkbond1 ----
bond_mode: active-backup
bond may use recirculation: no, Recirc-ID : -1
bond-hash-basis: 0
updelay: 0 ms
downdelay: 0 ms
lacp_status: off
active slave mac: aa:bb:cc:2c:ef:e0(dpdk2)

slave dpdk2: enabled
    active slave
    may_enable: true

slave dpdk3: disabled
    may_enable: false

[root@overcloud-compute-50 ~]# ovs-ofctl mod-port br-link dpdk3 up
ovs-ofctl: talking to unix:/var/run/openvswitch/br-link.mgmt (Connection reset by peer)