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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Mon, 26 Feb 2018 16:44:25 +0200
Message-ID: <CAHp75Vdpdr-0-vdvo0SBx2XcM=HePrUbbb4SM9+ExT_i-1B69Q@mail.gmail.com>
Subject: Re: [PATCH 01/21] powerpc: Remove warning on array size when empty
To:     Mathieu Malaterre <malat@debian.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Jiri Slaby <jslaby@suse.com>,
        "open list:LINUX FOR POWERPC PA SEMI PWRFICIENT" 
        <linuxppc-dev@lists.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sun, Feb 25, 2018 at 7:22 PM, Mathieu Malaterre <malat@debian.org> wrote=
:
> When neither CONFIG_ALTIVEC, nor CONFIG_VSX or CONFIG_PPC64 is defined, t=
he
> array feature_properties is defined as an empty array, which in turn
> triggers the following warning (treated as error on W=3D1):
>
>   CC      arch/powerpc/kernel/prom.o
> arch/powerpc/kernel/prom.c: In function =E2=80=98check_cpu_feature_proper=
ties=E2=80=99:
> arch/powerpc/kernel/prom.c:298:16: error: comparison of unsigned expressi=
on < 0 is always false [-Werror=3Dtype-limits]
>   for (i =3D 0; i < ARRAY_SIZE(feature_properties); ++i, ++fp) {
>                 ^
> cc1: all warnings being treated as errors
>
> Signed-off-by: Mathieu Malaterre <malat@debian.org>
> ---
>  arch/powerpc/kernel/prom.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 4dffef947b8a..6e8e4122820e 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -291,11 +291,10 @@ static inline void identical_pvr_fixup(unsigned lon=
g node)
>
>  static void __init check_cpu_feature_properties(unsigned long node)
>  {
> -       unsigned long i;
>         struct feature_property *fp =3D feature_properties;
>         const __be32 *prop;
>

Much simpler is just add

if (ARRAY_SIZE() =3D=3D 0)
 return;

> -       for (i =3D 0; i < ARRAY_SIZE(feature_properties); ++i, ++fp) {
> +       for (; fp !=3D feature_properties + ARRAY_SIZE(feature_properties=
); ++fp) {
>                 prop =3D of_get_flat_dt_prop(node, fp->name, NULL);
>                 if (prop && be32_to_cpup(prop) >=3D fp->min_value) {
>                         cur_cpu_spec->cpu_features |=3D fp->cpu_feature;
> --
> 2.11.0
>


--=20
With Best Regards,
Andy Shevchenko