Comment 0 for bug 1343262

Please submit a patch from this mailing list,
I will copy a content from it:

>-----Original Message-----
>From: Michal Privoznik [mailto:mprivozn redhat com]
>Sent: Thursday, July 03, 2014 8:39 PM
>To: Lichunhe; libvir-list redhat com
>Subject: Re: [libvirt] [PATCH]util:ovs:Delete port if it is exist when add port
>
>On 03.07.2014 13:57, Lichunhe wrote:
>> If the ovs service stop abnormal, or host cold reboot, vm is destroyed
>> after ovs service stop. The ovs port which connect to interface of vm
>> will not be clear. When the ovs service restart, recover configuration
>> from db, but the interface is no exist, port recovery failed, and then
>> vm restart on the same host, libvirt add port again, but the port
>> configuration is same as before, ovs will not connect the interface,
>> only store the configuration in db. Below will trigger this problem,
>>
>> virsh start vm
>> service openvswitch-switch stop
>> virsh destroy vm
>> service openvswitch-switch start
>> virsh start vm
>>
>>
>> Signed-off-by: Chunhe Li <lichunhe huawei com>
>> ---
>>
>> src/util/virnetdevopenvswitch.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/util/virnetdevopenvswitch.c
>> b/src/util/virnetdevopenvswitch.c index 9bcbfb1..dd601c0 100644
>> --- a/src/util/virnetdevopenvswitch.c
>> +++ b/src/util/virnetdevopenvswitch.c
>> @@ -84,7 +84,8 @@ int virNetDevOpenvswitchAddPort(const char *brname,
>> const char *ifname,
>>
>> cmd = virCommandNew(OVSVSCTL);
>>
>> - virCommandAddArgList(cmd, "--timeout=5", "--", "--may-exist",
>"add-port",
>> + virCommandAddArgList(cmd, "--timeout=5", "--", "--if-exists",
>"del-port",
>> + ifname, "--", "--may-exist", "add-port",
>> brname, ifname, NULL);
>
>So what's the meaning of '--may-exist' then? Does it do anything useful after all?
>
>Michal

Also here's a reproduction (forgive me these is in polish, forgot to do LANG=C)

root@cthulu ~ % virsh start xmbc
błąd: Uruchomienie domeny xmbc nie powiodło się
błąd: Unable to add port vnet4 to OVS bridge br-nfs: Operation not permitted

root@cthulu ~ % ovs-vsctl del-port vnet4
root@cthulu ~ % virsh start xmbc
Domena xmbc została uruchomiona

root@cthulu ~ % virsh start testy
błąd: Uruchomienie domeny testy nie powiodło się
błąd: Unable to add port vnet5 to OVS bridge ovbr0: Operation not permitted

root@cthulu ~ % virsh list --all
root@cthulu ~ % ovs-vsctl del-port vnet5
root@cthulu ~ % virsh start testy
błąd: Uruchomienie domeny testy nie powiodło się
błąd: Unable to add port vnet6 to OVS bridge br-nfs: Operation not permitted

root@cthulu ~ % ovs-vsctl del-port vnet6
root@cthulu ~ % virsh start testy
Domena testy została uruchomiona

Here is the original link:
http://www.redhat.com/archives/libvir-list/2014-July/msg00181.html