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Date:   Thu, 28 Oct 2021 12:46:55 -0300
From:   Isabella B do Amaral <isabellabdoamaral@....br>
To:     David Gow <davidgow@...gle.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Enzo Ferreira <ferreiraenzoa@...il.com>,
        Augusto Durães Camargo 
        <augusto.duraes33@...il.com>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Daniel Latypov <dlatypov@...gle.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        KUnit Development <kunit-dev@...glegroups.com>,
        ~lkcamp/patches@...ts.sr.ht,
        Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>
Subject: Re: [PATCH v2 1/5] hash.h: remove unused define directive

Hi, David,

On Sat, Oct 2, 2021 at 4:20 AM David Gow <davidgow@...gle.com> wrote:
>
> On Mon, Sep 27, 2021 at 6:33 AM Isabella Basso <isabellabdoamaral@....br> wrote:
> >
> > Currently, there exist hash_32() and __hash_32() functions, which were
> > introduced in a patch [1] targeting architecture specific optimizations.
> > These functions can be overridden on a per-architecture basis to achieve
> > such optimizations. They must set their corresponding define directive
> > (HAVE_ARCH_HASH_32 and HAVE_ARCH__HASH_32, respectively) so that header
> > files can deal with these overrides properly.
> >
> > As the supported 32-bit architectures that have their own hash function
> > implementation (i.e. m68k, Microblaze, H8/300, pa-risc) have only been
> > making use of the (more general) __hash_32() function (which only lacks
> > a right shift operation when compared to the hash_32() function),
> > remove the define directive corresponding to the arch-specific hash_32()
> > implementation.
> >
> > [1] https://lore.kernel.org/lkml/20160525073311.5600.qmail@ns.sciencehorizons.net/
> >
> > Changes since v1:
> > - As suggested by David Gow:
> >   1. Reword commit message.
>
> Maybe move this changelog to below the "---", so it doesn't show up in
> the final commit message?

Oh, okay! Thanks for pointing that out :) I didn't quite know how I
should put these.

>
> >
> > Tested-by: David Gow <davidgow@...gle.com>
> > Co-developed-by: Augusto Durães Camargo <augusto.duraes33@...il.com>
> > Signed-off-by: Augusto Durães Camargo <augusto.duraes33@...il.com>
> > Co-developed-by: Enzo Ferreira <ferreiraenzoa@...il.com>
> > Signed-off-by: Enzo Ferreira <ferreiraenzoa@...il.com>
> > Signed-off-by: Isabella Basso <isabellabdoamaral@....br>
> > ---
>
> This looks sensible enough to me. Since no-one seems to be speaking up
> in architecture-specific hash_32()'s defence, let's get rid of it.
>
> Reviewed-by: David Gow <davidgow@...gle.com>
>

Alright! Thanks for the review.

Cheers,
--
Isabella B.

>
> >  include/linux/hash.h       |  5 +----
> >  lib/test_hash.c            | 24 +-----------------------
> >  tools/include/linux/hash.h |  5 +----
> >  3 files changed, 3 insertions(+), 31 deletions(-)
> >
> > diff --git a/include/linux/hash.h b/include/linux/hash.h
> > index ad6fa21d977b..38edaa08f862 100644
> > --- a/include/linux/hash.h
> > +++ b/include/linux/hash.h
> > @@ -62,10 +62,7 @@ static inline u32 __hash_32_generic(u32 val)
> >         return val * GOLDEN_RATIO_32;
> >  }
> >
> > -#ifndef HAVE_ARCH_HASH_32
> > -#define hash_32 hash_32_generic
> > -#endif
> > -static inline u32 hash_32_generic(u32 val, unsigned int bits)
> > +static inline u32 hash_32(u32 val, unsigned int bits)
> >  {
> >         /* High bits are more random, so use them. */
> >         return __hash_32(val) >> (32 - bits);
> > diff --git a/lib/test_hash.c b/lib/test_hash.c
> > index 0ee40b4a56dd..d4b0cfdb0377 100644
> > --- a/lib/test_hash.c
> > +++ b/lib/test_hash.c
> > @@ -94,22 +94,7 @@ test_int_hash(unsigned long long h64, u32 hash_or[2][33])
> >                         pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);
> >                         return false;
> >                 }
> > -#ifdef HAVE_ARCH_HASH_32
> > -               h2 = hash_32_generic(h0, k);
> > -#if HAVE_ARCH_HASH_32 == 1
> > -               if (h1 != h2) {
> > -                       pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "
> > -                               " = %#x", h0, k, h1, h2);
> > -                       return false;
> > -               }
> > -#else
> > -               if (h2 > m) {
> > -                       pr_err("hash_32_generic(%#x, %d) = %#x > %#x",
> > -                               h0, k, h1, m);
> > -                       return false;
> > -               }
> > -#endif
> > -#endif
> > +
> >                 /* Test hash_64 */
> >                 hash_or[1][k] |= h1 = hash_64(h64, k);
> >                 if (h1 > m) {
> > @@ -227,13 +212,6 @@ test_hash_init(void)
> >  #else
> >         pr_info("__hash_32() has no arch implementation to test.");
> >  #endif
> > -#ifdef HAVE_ARCH_HASH_32
> > -#if HAVE_ARCH_HASH_32 != 1
> > -       pr_info("hash_32() is arch-specific; not compared to generic.");
> > -#endif
> > -#else
> > -       pr_info("hash_32() has no arch implementation to test.");
> > -#endif
> >  #ifdef HAVE_ARCH_HASH_64
> >  #if HAVE_ARCH_HASH_64 != 1
> >         pr_info("hash_64() is arch-specific; not compared to generic.");
> > diff --git a/tools/include/linux/hash.h b/tools/include/linux/hash.h
> > index ad6fa21d977b..38edaa08f862 100644
> > --- a/tools/include/linux/hash.h
> > +++ b/tools/include/linux/hash.h
> > @@ -62,10 +62,7 @@ static inline u32 __hash_32_generic(u32 val)
> >         return val * GOLDEN_RATIO_32;
> >  }
> >
> > -#ifndef HAVE_ARCH_HASH_32
> > -#define hash_32 hash_32_generic
> > -#endif
> > -static inline u32 hash_32_generic(u32 val, unsigned int bits)
> > +static inline u32 hash_32(u32 val, unsigned int bits)
> >  {
> >         /* High bits are more random, so use them. */
> >         return __hash_32(val) >> (32 - bits);
> > --
> > 2.33.0
> >

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