linux-kernel - Re: [RFC v2 2/3] atomic: Specify alignment for atomic_t and atomic64

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Message-ID: <CAMuHMdXOnUXJbhifdyYY50fo5zoG=FH6Rvp64mQHBB9yQRyiVA@mail.gmail.com>
Date: Mon, 15 Sep 2025 09:13:28 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Finn Thain <fthain@...ux-m68k.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Will Deacon <will@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Boqun Feng <boqun.feng@...il.com>, 
	Jonathan Corbet <corbet@....net>, Mark Rutland <mark.rutland@....com>, Arnd Bergmann <arnd@...db.de>, 
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, 
	linux-m68k@...r.kernel.org, Lance Yang <lance.yang@...ux.dev>
Subject: Re: [RFC v2 2/3] atomic: Specify alignment for atomic_t and atomic64_t

Hi Finn,

Thanks for your patch!

On Sun, 14 Sept 2025 at 02:59, Finn Thain <fthain@...ux-m68k.org> wrote:
> Some recent commits incorrectly assumed 4-byte alignment of locks.
> That assumption fails on Linux/m68k (and, interestingly, would have
> failed on Linux/cris also). Specify the minimum alignment of atomic
> variables for fewer surprises and (hopefully) better performance.
>
> Consistent with i386, atomic64_t is not given natural alignment here.

You forgot to drop this line.

>
> Cc: Lance Yang <lance.yang@...ux.dev>
> Link: https://lore.kernel.org/lkml/CAMuHMdW7Ab13DdGs2acMQcix5ObJK0O2dG_Fxzr8_g58Rc1_0g@mail.gmail.com/
> ---
> Changed since v1:
>  - atomic64_t now gets an __aligned attribute too.

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