[ovs-dev] [PATCH 2/3] netdev-linux: make tap devices persistent.

Flavio Leitner fbl at sysclose.org
Mon Jun 19 19:01:45 UTC 2017


Hi Vishal,


On Thu, Jun 08, 2017 at 02:22:38PM -0300, Flavio Leitner wrote:
> On Thu, Jun 08, 2017 at 11:24:58AM +0000, Vishal Deep Ajmera wrote:
> > Hi Flavio,
> > 
> > I am facing some issue with ovs-master on Ubuntu 14.04 system. Here are the steps I followed and the error message I get. Can it be possibly related to your patch for making tap device persistent ? Let me know if I am missing some steps here.
> > 
> > 1. Create netdev bridge
> > $ ovs-vsctl add-br br0 -- set Bridge br0 datapath_type=netdev
> > $ ovs-vsctl show
> > 4c516433-c305-4894-96ad-f44af0b01b63
> >     Bridge "br0"
> >         Port "br0"
> >             Interface "br0"
> >                 type: internal
> >     ovs_version: "2.7.90"
> > 
> > 2. Bring up br0 interface
> > $ ifconfig br0 up
> > 
> > 3. Restart the openvswitch
> > $ service openvswitch-switch restart
> > 
> > 4. Show ovs db
> > $ ovs-vsctl show
> > 4c516433-c305-4894-96ad-f44af0b01b63
> >     Bridge "br0"
> >         Port "br0"
> >             Interface "br0"
> >                 type: internal
> >                 error: "could not open network device br0 (File exists)"
> >     ovs_version: "2.7.90"
> 
> 
> The same thing Eric reported to me when a test unit had failed.
> Oddly I can't reproduce (yet), but reviewing the code seems that a
> rtnetlink to add a route can open the device but not add to the DP, 
> then when it tries to that error would be reported.
> 
> I will look more into it and see if I can fix it.

I think I have reproduced the issue here and it only happens if you
have an IP address on a port. Could you confirm that?

If so, OVS will receive rtnetlink msgs from each device with routes.
That creates netdev objects before they are added to the datapath.
Then when vswitchd is configuring the datapath, netdev_open() returns
EEXIST error preventing the device to be added.

It looks like related to this commit:
https://github.com/openvswitch/ovs/commit/67ac844b55d4c5f6bbfa01773c82b3d6d8b62131

Could you revert it and see if the issue goes away?

Thanks,
-- 
Flavio



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