[ovs-dev] [PATCH ovn 2/3] northd: update stage-name if changed

Dumitru Ceara dceara at redhat.com
Thu Jun 24 15:44:49 UTC 2021

On 6/22/21 7:25 AM, Han Zhou wrote:
> On Sat, Jun 19, 2021 at 2:51 AM Mark Gray <mark.d.gray at redhat.com> wrote:
>> If a new table is added to a logical flow pipeline, the mapping between
>> 'external_ids:stage-name' from the 'Logical_Flow' table in the
>> 'OVN_Southbound' database and the 'stage' number may change for some
> tables.
>> If 'ovn-northd' is started against a populated Southbound database,
>> 'external_ids:stage-name' will not be updated to reflect the new, correct
>> name. This will cause the stage name to be incorrectly displayed by some
>> tools and commands such as `ovn-sbctl dump-flows`.
>> This commit, reconciles changes to the stage name as part of
> build_lflows().
> This is interesting. It means a flow F existed in stage S (named "foo") of
> ovn-northd version V1, and in version V2, S becomes S + 1 ("foo"), but in
> the V2's stage S ("bar") there happens to be an exactly same flow like F
> existing, but the stage name shown in ovn-sbctl dump-flows will be "foo"
> instead of "bar". Is this the scenario the patch is trying to fix?
> If so, I think it is better not only fixing the "stage-name" but also other
> external_ids, including "source" and "stage-hint", for the same reason.

Hi Mark, Han,

Wouldn't this cause lots of additional string comparisons?  What if we
restrict ourselves to checking one flow per stage (for each ovn-northd
iteration).  Would that be enough to detect that we need to update all
of them?

This might be an ugly hack though. :)


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