Re: [PATCH net-next 1/2] net: sparx5: flower: cleanup sparx5_tc_flower_handler_control_usage()

[Asbjørn Sloth Tønnesen]

Hi Daniel,

Thank you for the review.

On 4/23/24 11:15 AM, Daniel Machon wrote:
> Hi Asbjørn,
>
> Thank you for your patch!
>
> > Define extack locally, to reduce line lengths and future users.
> >
> > Only perform fragment handling, when at least one fragment flag is set.
> >
> > Remove goto, as it's only used once, and the error message is specific
> > to that context.
> >
> > Only compile tested.
> >
> > Signed-off-by: Asbjørn Sloth Tønnesen <ast@xxxxxxxxxxx>
> > ---
> >   .../ethernet/microchip/sparx5/sparx5_tc_flower.c    | 13 ++++++-------
> >   1 file changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_tc_flower.c b/drivers/net/ethernet/microchip/sparx5/sparx5_tc_flower.c
> > index 663571fe7b2d..d846edd77a01 100644
> > --- a/drivers/net/ethernet/microchip/sparx5/sparx5_tc_flower.c
> > +++ b/drivers/net/ethernet/microchip/sparx5/sparx5_tc_flower.c
> > @@ -159,13 +159,14 @@ sparx5_tc_flower_handler_basic_usage(struct vcap_tc_flower_parse_usage *st)
> >   static int
> >   sparx5_tc_flower_handler_control_usage(struct vcap_tc_flower_parse_usage *st)
> >   {
> > +       struct netlink_ext_ack *extack = st->fco->common.extack;
>
> Could you please update the use of extack in all places inside this
> function. You are missing one place.

Good catch, sure. It must have got lost somewhere along the way. I deliberately kept it out
of the net patch, since it could wait for net-next.


> >          struct flow_match_control mt;
> >          u32 value, mask;
> >          int err = 0;
> >
> >          flow_rule_match_control(st->frule, &mt);
> >
> > -       if (mt.mask->flags) {
> > +       if (mt.mask->flags & (FLOW_DIS_IS_FRAGMENT | FLOW_DIS_FIRST_FRAG)) {
>
> Since these flags are used here and in the next patch, maybe assign them
> to a variable:
>
> u32 supp_flags = FLOW_DIS_IS_FRAGMENT | FLOW_DIS_FIRST_FRAG
>
> And update the use throughout.

In an earlier state this patch had a #define SPARX5_FLOWER_SUPPORTED_CTLFLAGS,
in the same style as nfp in drivers/net/ethernet/netronome/nfp/flower/offload.c

Right now, this driver supports all currently defined flags (which are used with mask),
so the point of using flow_rule_is_supp_control_flags() to this dirver, is to
make it possible to introduce new flags in the future, without having to update
all drivers to explicitly not support a new flag.

My problem with using supp_flags in both places is: What happens when support
for a new flag is introduced?

u32 supp_flags = FLOW_DIS_IS_FRAGMENT | FLOW_DIS_FIRST_FRAG | FLOW_DIS_NEW_FLAG;

if (mt.mask->flags & (FLOW_DIS_IS_FRAGMENT | FLOW_DIS_FIRST_FRAG))
        /* handle fragment flags through lookup table */

if (mt.mask->flags & FLOW_DIS_NEW_FLAG)
        /* do something */

if (!flow_rule_is_supp_control_flags(supp_flags, mt.mask->flags, extack))
        return -EOPNOTSUPP;

The fragment lookup table code currently requires the above guarding,
as [0][0] in the lookup table is FRAG_INVAL, and not FRAG_SHRUG.

What do you think?

--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541