Description of problem:
The ovs-dpdk pmd threads are re-created when new vm with vhostuser port is atttached.

Version-Release number of selected component (if applicable):
openvswitch-2.6.1-4.1.git20161206.el7.x86_64
dpdk-16.11-5.el7fdb.x86_64

How reproducible:
It's reproducible everytime

Steps to Reproduce:
1. start ovs with following other_config
{dpdk-init="true", dpdk-lcore-mask="0xc", dpdk-socket-mem="2048,2048", pmd-cpu-mask="0xf0"}
2. check the LWP/TID of the pmd thread.
# ps -eL | grep pmd
   6748  109368 ?        00:00:13 pmd231
   6748  109369 ?        00:00:13 pmd230
# ovs-appctl dpif-netdev/pmd-rxq-show                                                        
pmd thread numa_id 0 core_id 4:
        isolated : false
        port: dpdk1     queue-id: 0
        port: vhud13fa949-7c    queue-id: 0
pmd thread numa_id 0 core_id 6:
        isolated : false
        port: dpdk0     queue-id: 0
        port: vhue0018a81-1a    queue-id: 0

3. boot up a vm with a vhostuser interface.

4. check the LWP/TID of the pmd thread.
#ps -eL | grep pmd
   6748  109510 ?        00:05:55 pmd233
   6748  109511 ?        00:05:55 pmd232

# ovs-appctl dpif-netdev/pmd-rxq-show                                                        
pmd thread numa_id 0 core_id 4:
        isolated : false
        port: dpdk1     queue-id: 0
        port: vhud13fa949-7c    queue-id: 0
        port: vhu0b3ae154-42    queue-id: 0
pmd thread numa_id 0 core_id 6:
        isolated : false
        port: dpdk0     queue-id: 0
        port: vhue0018a81-1a    queue-id: 0
        port: vhu4a4c10d1-86    queue-id: 0

Actual results:
The TID of PMD thread has changed. It means the PMD threads were re-created.

Expected results:
The thread should not be re-created, otherwise there will cause packet loss to existing ports, which should be avoid in NFV use case.


Additional info: