linux-kernel - Re: [PATCH cmpxchg 13/14] xtensa: Emulate one-byte cmpxchg

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Date: Thu, 18 Apr 2024 10:06:21 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org, elver@...gle.com, 
	akpm@...ux-foundation.org, tglx@...utronix.de, peterz@...radead.org, 
	dianders@...omium.org, pmladek@...e.com, torvalds@...ux-foundation.org, 
	Arnd Bergmann <arnd@...db.de>, Yujie Liu <yujie.liu@...el.com>, 
	Andi Shyti <andi.shyti@...ux.intel.com>
Subject: Re: [PATCH cmpxchg 13/14] xtensa: Emulate one-byte cmpxchg

Hi Paul,

On Mon, Apr 8, 2024 at 7:49 PM Paul E. McKenney <paulmck@...nel.org> wrote:
> Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on xtensa.
>
> [ paulmck: Apply kernel test robot feedback. ]
> [ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
>
> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>

Thanks for your patch!

> --- a/arch/xtensa/include/asm/cmpxchg.h
> +++ b/arch/xtensa/include/asm/cmpxchg.h
> @@ -74,6 +75,7 @@ static __inline__ unsigned long
>  __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
>  {
>         switch (size) {
> +       case 1:  return cmpxchg_emu_u8((volatile u8 *)ptr, old, new);

The cast is not needed.

>         case 4:  return __cmpxchg_u32(ptr, old, new);
>         default: __cmpxchg_called_with_bad_pointer();
>                  return old;

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg

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