linux-kernel - Re: [PATCH 13/13] atomics/treewide: make test ops optional

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Date:   Wed, 23 May 2018 16:03:35 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will.deacon@....com>
Subject: Re: [PATCH 13/13] atomics/treewide: make test ops optional

On Wed, May 23, 2018 at 3:35 PM, Mark Rutland <mark.rutland@....com> wrote:
> Some of the atomics return the result of a test applied after the atomic
> operation, and almost all architectures implement these as trivial
> wrappers around the underlying atomic. Specifically:
>
> * <atomic>_inc_and_test(v) is (<atomic>_inc_return(v) == 0)
>
> * <atomic>_dec_and_test(v) is (<atomic>_dec_return(v) == 0)
>
> * <atomic>_sub_and_test(i, v) is (<atomic>_sub_return(i, v) == 0)
>
> * <atomic>_add_negative(i, v) is (<atomic>_add_return(i, v) < 0)
>
> Rather than have these definitions duplicated in all architectures, with
> minor inconsistencies in formatting and documentation, let's make these
> operations optional, with default fallbacks as above. Implementations
> must now provide a preprocessor symbol.
>
> The instrumented atomics are updated accordingly.
>
> Both x86 and m68k have custom implementations, which are left as-is,
> given preprocessor symbols to avoid being overridden.
>
> There should be no functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@....com>

>  arch/m68k/include/asm/atomic.h            |   4 +

For m68k:
Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds