[ovs-dev] [PATCH] ofproto-dpif-xlate: Always generate wildcards.

[Ben Pfaff]

On Sat, Apr 23, 2016 at 03:40:56PM -0500, Ryan Moats wrote:
> "dev" <dev-bounces at openvswitch.org> wrote on 04/22/2016 07:45:03 PM:
> 
> > From: Ben Pfaff <blp at ovn.org>
> > To: dev at openvswitch.org
> > Cc: Ben Pfaff <blp at ovn.org>
> > Date: 04/22/2016 07:45 PM
> > Subject: [ovs-dev] [PATCH] ofproto-dpif-xlate: Always generate wildcards.
> > Sent by: "dev" <dev-bounces at openvswitch.org>
> >
> > Until now, the flow translation code has tried to avoid constructing a
> > set of wildcards during translation in the cases where it can, because
> > wildcards are large and somewhat expensive.  However, this has problems
> > that we hadn't previously realized.  Specifically, the generated actions
> > can depend on the constructed wildcards, to decide which bits of a field
> > need to be set in a masked set_field action.  This means that in practice
> > translation needs to always construct the wildcards.
> >
> > (It might be possible to avoid masked set_field when we're not
> constructing
> > wildcards, but this would mean that we'd generate different actions
> > depending on whether wildcards were being constructed, which seems rather
> > confusing at best.  Also, the cases in which we don't need wildcards
> anyway
> > are fairly obscure, meaning that the benefits of avoiding them in those
> > cases are minimal and that it's going to be hard to get test coverage.
> The
> > latter is probably why we didn't notice this until now.)
> >
> > Reported-by: William Tu <u9012063 at gmail.com>
> > Reported-at: http://openvswitch.org/pipermail/dev/2016-April/069219.html
> > Signed-off-by: Ben Pfaff <blp at ovn.org>
> > ---
> >  ofproto/ofproto-dpif-xlate.c | 21 ++++++++-------------
> 
> As promised:
> 
> Acked-by: Ryan Moats <rmoats at us.ibm.com>

Thanks, I applied this to master and branch-2.5.