[PATCHv2 1/4] fwu: gpt: use cached meta-data partition numbers

[Jassi Brar]

On Thu, 22 Dec 2022 at 06:45, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> On Fri, Dec 02, 2022 at 09:16:51PM -0600, jassisinghbrar at gmail.com wrote:
> > From: Jassi Brar <jaswinder.singh at linaro.org>
> >
> > Use cached values and avoid parsing and scanning through partitions
> > everytime for meta-data partitions because they can't change after bootup.
> >
> > Acked-by: Etienne Carriere <etienne.carriere at linaro.org>
> > Signed-off-by: Jassi Brar <jaswinder.singh at linaro.org>
> > ---
> >  drivers/fwu-mdata/gpt_blk.c | 43 +++++++++++++++++++++----------------
> >  1 file changed, 24 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/fwu-mdata/gpt_blk.c b/drivers/fwu-mdata/gpt_blk.c
> > index d35ce49c5c..28f5d23e1e 100644
> > --- a/drivers/fwu-mdata/gpt_blk.c
> > +++ b/drivers/fwu-mdata/gpt_blk.c
> > @@ -24,8 +24,9 @@ enum {
> >       MDATA_WRITE,
> >  };
> >
> > -static int gpt_get_mdata_partitions(struct blk_desc *desc,
> > -                                 uint mdata_parts[2])
> > +static uint g_mdata_part[2]; /* = {0, 0} to check against uninit parts */
> > +
> > +static int gpt_get_mdata_partitions(struct blk_desc *desc)
> >  {
> >       int i, ret;
> >       u32 nparts;
> > @@ -33,18 +34,19 @@ static int gpt_get_mdata_partitions(struct blk_desc *desc,
> >       struct disk_partition info;
> >       const efi_guid_t fwu_mdata_guid = FWU_MDATA_GUID;
> >
> > +     /* if primary and secondary partitions already found */
> > +     if (g_mdata_part[0] && g_mdata_part[1])
> > +             return 0;
> > +
> >       nparts = 0;
> > -     for (i = 1; i < MAX_SEARCH_PARTITIONS; i++) {
> > +     for (i = 1; i < MAX_SEARCH_PARTITIONS && nparts < 2; i++) {
> >               if (part_get_info(desc, i, &info))
> >                       continue;
> >               uuid_str_to_bin(info.type_guid, part_type_guid.b,
> >                               UUID_STR_FORMAT_GUID);
> >
> > -             if (!guidcmp(&fwu_mdata_guid, &part_type_guid)) {
> > -                     if (nparts < 2)
> > -                             mdata_parts[nparts] = i;
> > -                     ++nparts;
> > -             }
> > +             if (!guidcmp(&fwu_mdata_guid, &part_type_guid))
> > +                     g_mdata_part[nparts++] = i;
>
> The reason the 'if (nparts < 2)' was outside the main loop was to show
> errors in case the user defined more than two partitions.  Can we keep it
> like that or am I the only being paranoid here?
>
I am not sure if that is an 'error', because FWU only cares about the
first two partitions it comes across. There is no way other ones could
impact the operations.
And if fwu code is responsible for correctness of the setup, there are
things that we already don't care about. So maybe we keep the code
simple?

cheers.