[ovs-dev] [PATCH] ovn-controller: Reset flow processing after (re)connection to switch

[Numan Siddique]

On Tue, Aug 9, 2016 at 7:15 PM, Ryan Moats <rmoats at us.ibm.com> wrote:

> "dev" <dev-bounces at openvswitch.org> wrote on 08/09/2016 07:19:27 AM:
>
> > From: Numan Siddique <nusiddiq at redhat.com>
> > To: ovs dev <dev at openvswitch.org>
> > Date: 08/09/2016 07:19 AM
> > Subject: [ovs-dev] [PATCH] ovn-controller: Reset flow processing
> > after (re)connection to switch
> > Sent by: "dev" <dev-bounces at openvswitch.org>
> >
> > When ovn-controller reconnects to the ovs-vswitchd, it deletes all the
> > OF flows in the switch. It doesn't install the flows again, leaving
> > the datapath broken unless ovn-controller is restarted or ovn-northd
> > updates the SB DB.
> >
> > The reason for this is
> >   - lflow_reset_processing() is not called after the reconnection
> >   - the hmap "installed_flows" is not cleared, because of which
> >     ofctrl_put skips adding the flows to the switch.
> >
> > This patch fixes the issue and also adds a test case to test
> > this scenario.
> >
> > Signed-off-by: Numan Siddique <nusiddiq at redhat.com>
> > ---
>
> I'm going to pick a nit on this one - is the behavior you are aiming
> for delete and re-add or just recalculate and leave alone?
>
>
​
In my testing I am seeing that all the OF flows are getting de​leted when I
restart ovs-vswitchd.
I am testing with the latest master of OVS. I am able to see this on 2
different machines and also in sandbox.

I thought that ovn-controller is deleting the flows in the switch when it
restarts (
https://github.com/openvswitch/ovs/blob/master/ovn/controller/ofctrl.c#L355)

Now I tested again and before restarting ovs-vswitchd, I killed
ovn-controller. Looks like ovs-vswitchd is clearing the old flows when it
restarts. I am not sure if this is the intended behavior. Looks like it is.
Please correct me if I am wrong here.


​You can run below commands to reproduce the issue in sandbox​

-----------------------------
 $make sandbox SANDBOXFLAGS="--ovn"
 $ovn/env1/setup.sh
 $ovs-ofctl dump-flows br-int
 $ovs-appctl -t ovn-controller exit
 $ovs-appctl -t ovs-vswitchd exit
​ $ovs-vswitchd --detach --no-chdir --pidfile -vconsole:off --log-file
--enable-dummy=override -vvconn -vnetdev_dummy
 $ ovs-ofctl dump-flows br-int
NXST_FLOW reply (xid=0x4):
------------------------------------


You will see that the flows are deleted even if you don't run - "ovs-appctl
-t ovn-controller exit".




I ask because if it is "delete and re-add" aren't you still disrupting
> the datapath even if only momentarily?
>
>
>