netdev - Re: [PATCH iproute2-next v2 4/8] dcb: app: modify dcb_app_parse_mapping

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Date: Wed, 31 May 2023 08:12:17 +0000
From: Daniel Machon <daniel.machon@...rochip.com>
To: Petr Machata <petrm@...dia.com>
CC: <netdev@...r.kernel.org>, <dsahern@...nel.org>,
	<stephen@...workplumber.org>, <UNGLinuxDriver@...rochip.com>
Subject: Re: [PATCH iproute2-next v2 4/8] dcb: app: modify
 dcb_app_parse_mapping_cb for dcb-rewr reuse

> Daniel Machon <daniel.machon@...rochip.com> writes:
> 
> > When parsing APP table entries, priority and protocol is assigned from
> > value and key, respectively. Rewrite requires it opposite.
> >
> > Adapt the existing dcb_app_parse_mapping_cb for this, by using callbacks
> > for pushing app or rewr entries to the table.
> >
> > Signed-off-by: Daniel Machon <daniel.machon@...rochip.com>
> > ---
> >  dcb/dcb.h     | 12 ++++++++++++
> >  dcb/dcb_app.c | 23 ++++++++++++-----------
> >  2 files changed, 24 insertions(+), 11 deletions(-)
> >
> > diff --git a/dcb/dcb.h b/dcb/dcb.h
> > index 84ce95d5c1b2..b3bc30cd02c5 100644
> > --- a/dcb/dcb.h
> > +++ b/dcb/dcb.h
> > @@ -62,7 +62,16 @@ struct dcb_app_table {
> >       int attr;
> >  };
> >
> > +struct dcb_app_parse_mapping {
> > +     __u8 selector;
> > +     struct dcb_app_table *tab;
> > +     int (*push)(struct dcb_app_table *tab,
> > +                 __u8 selector, __u32 key, __u64 value);
> > +     int err;
> > +};
> > +
> >  int dcb_cmd_app(struct dcb *dcb, int argc, char **argv);
> > +
> >  enum ieee_attrs_app dcb_app_attr_type_get(__u8 selector);
> >  bool dcb_app_attr_type_validate(enum ieee_attrs_app type);
> >  bool dcb_app_selector_validate(enum ieee_attrs_app type, __u8 selector);
> > @@ -70,11 +79,14 @@ bool dcb_app_selector_validate(enum ieee_attrs_app type, __u8 selector);
> >  bool dcb_app_pid_eq(const struct dcb_app *aa, const struct dcb_app *ab);
> >  bool dcb_app_prio_eq(const struct dcb_app *aa, const struct dcb_app *ab);
> >
> > +int dcb_app_table_push(struct dcb_app_table *tab, struct dcb_app *app);
> >  void dcb_app_table_remove_replaced(struct dcb_app_table *a,
> >                                  const struct dcb_app_table *b,
> >                                  bool (*key_eq)(const struct dcb_app *aa,
> >                                                 const struct dcb_app *ab));
> >
> > +void dcb_app_parse_mapping_cb(__u32 key, __u64 value, void *data);
> > +
> >  /* dcb_apptrust.c */
> >
> >  int dcb_cmd_apptrust(struct dcb *dcb, int argc, char **argv);
> > diff --git a/dcb/dcb_app.c b/dcb/dcb_app.c
> > index 4cd175a0623b..97cba658aa6b 100644
> > --- a/dcb/dcb_app.c
> > +++ b/dcb/dcb_app.c
> > @@ -105,7 +105,7 @@ static void dcb_app_table_fini(struct dcb_app_table *tab)
> >       free(tab->apps);
> >  }
> >
> > -static int dcb_app_table_push(struct dcb_app_table *tab, struct dcb_app *app)
> > +int dcb_app_table_push(struct dcb_app_table *tab, struct dcb_app *app)
> >  {
> >       struct dcb_app *apps = realloc(tab->apps, (tab->n_apps + 1) * sizeof(*tab->apps));
> >
> > @@ -231,25 +231,25 @@ static void dcb_app_table_sort(struct dcb_app_table *tab)
> >       qsort(tab->apps, tab->n_apps, sizeof(*tab->apps), dcb_app_cmp_cb);
> >  }
> >
> > -struct dcb_app_parse_mapping {
> > -     __u8 selector;
> > -     struct dcb_app_table *tab;
> > -     int err;
> > -};
> > -
> > -static void dcb_app_parse_mapping_cb(__u32 key, __u64 value, void *data)
> > +static int dcb_app_push(struct dcb_app_table *tab,
> > +                     __u8 selector, __u32 key, __u64 value)
> >  {
> > -     struct dcb_app_parse_mapping *pm = data;
> >       struct dcb_app app = {
> > -             .selector = pm->selector,
> > +             .selector = selector,
> >               .priority = value,
> >               .protocol = key,
> >       };
> > +     return dcb_app_table_push(tab, &app);
> > +}
> > +
> > +void dcb_app_parse_mapping_cb(__u32 key, __u64 value, void *data)
> > +{
> > +     struct dcb_app_parse_mapping *pm = data;
> >
> >       if (pm->err)
> >               return;
> >
> > -     pm->err = dcb_app_table_push(pm->tab, &app);
> > +     pm->err = pm->push(pm->tab, pm->selector, key, value);
> >  }
> >
> >  static int dcb_app_parse_mapping_ethtype_prio(__u32 key, char *value, void *data)
> > @@ -663,6 +663,7 @@ static int dcb_cmd_app_parse_add_del(struct dcb *dcb, const char *dev,
> >  {
> >       struct dcb_app_parse_mapping pm = {
> >               .tab = tab,
> > +             .push = dcb_app_push,
> >       };
> >       int ret;
> 
> I think I misunderstood your code. Since you are adding new functions
> for parsing the PRIO-DSCP and PRIO-PCP mappings, which have their own
> dcb_parse_mapping() invocations, couldn't you just copy over the
> dcb_app_parse_mapping_cb() from APP and adapt it to do the right thing
> for REWR? Then the push callback is not even necessary
> dcb_app_parse_mapping_cb() does not need to be public.

It is always a balance of when to do what. So far, patches #2, #3 and #4
tries to modify the existing dcb-app functions for dcb-rewr reuse. They
all deal with the prio:pid, pid:prio problem (printing, pushing and
replacing entries). What you suggest now is to copy
dcb_app_parse_mapping_cb() entirely, just for changing that order. It
can be done, but then it could also be done for #2 and #3, which would
then result in more boilerplate code.

Whatever we choose, I think we should stay consistent?