linux-kernel - Re: [PATCH] provide arch_test_bit_acquire for architectures that define test

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Message-ID: <CAHk-=wgCN6moKefrRBECCon6675vh=6+yWGu0N5zu7G5eGh+wg@mail.gmail.com>
Date:   Fri, 26 Aug 2022 13:07:24 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Mikulas Patocka <mpatocka@...hat.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Brian Cain <bcain@...cinc.com>, linux-hexagon@...r.kernel.org,
        Alan Stern <stern@...land.harvard.edu>,
        Andrea Parri <parri.andrea@...il.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Nicholas Piggin <npiggin@...il.com>,
        David Howells <dhowells@...hat.com>,
        Jade Alglave <j.alglave@....ac.uk>,
        Luc Maranget <luc.maranget@...ia.fr>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Akira Yokosawa <akiyks@...il.com>,
        Daniel Lustig <dlustig@...dia.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH] provide arch_test_bit_acquire for architectures that
 define test_bit

[ Crossed emails ]

On Fri, Aug 26, 2022 at 1:03 PM Mikulas Patocka <mpatocka@...hat.com> wrote:
>
> +static __always_inline bool
> +arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
> +{
> +       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
> +       return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1)));
> +}
> +

I'd suggest you just do

  #define arch_test_bit_acquire generic_test_bit_acquire

in each of these files, instead of duplicating that function over and
over again..

Because the generic version always exists, since it comes from
generic-non-atomic.h, which is included directly from
<linux/bitops.h>.

                  Linus