linux-kernel - Re: [PATCH v2 2/4] locking/atomic: arc: arch_cmpxchg[64]

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Date:   Wed, 8 Nov 2023 10:02:48 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     "wuqiang.matt" <wuqiang.matt@...edance.com>
Cc:     vgupta@...nel.org, bcain@...cinc.com, jonas@...thpole.se,
        stefan.kristiansson@...nalahti.fi, shorne@...il.com,
        geert@...ux-m68k.org, andi.shyti@...ux.intel.com, mingo@...nel.org,
        palmer@...osinc.com, andrzej.hajda@...el.com, arnd@...db.de,
        peterz@...radead.orgm, linux-snps-arc@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-hexagon@...r.kernel.org,
        linux-openrisc@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        mattwu@....com, linux@...ck-us.ne
Subject: Re: [PATCH v2 2/4] locking/atomic: arc: arch_cmpxchg[64]_local
 undefined

On Sat,  4 Nov 2023 17:16:13 +0800
"wuqiang.matt" <wuqiang.matt@...edance.com> wrote:

> For architectures that support native cmpxchg, we'd like to
> implement arch_cmpxchg[64]_local with the native variants of
> supported data size. If not, the generci_cmpxchg[64]_local
> will be used.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

> Signed-off-by: wuqiang.matt <wuqiang.matt@...edance.com>
> ---
>  arch/arc/include/asm/cmpxchg.h | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
> index bf46514f6f12..91429f2350df 100644
> --- a/arch/arc/include/asm/cmpxchg.h
> +++ b/arch/arc/include/asm/cmpxchg.h
> @@ -80,6 +80,34 @@
>  
>  #endif
>  
> +/*
> + * always make arch_cmpxchg[64]_local available, native cmpxchg
> + * will be used if available, then generic_cmpxchg[64]_local
> + */
> +#include <asm-generic/cmpxchg-local.h>
> +static inline unsigned long __cmpxchg_local(volatile void *ptr,
> +				      unsigned long old,
> +				      unsigned long new, int size)
> +{
> +	switch (size) {
> +#ifdef CONFIG_ARC_HAS_LLSC
> +	case 4:
> +		return __cmpxchg_32((int32_t *)ptr, old, new);
> +#endif
> +	default:
> +		return __generic_cmpxchg_local(ptr, old, new, size);
> +	}
> +
> +	return old;
> +}
> +#define arch_cmpxchg_local(ptr, o, n) ({				\
> +	(__typeof__(*ptr))__cmpxchg_local((ptr),			\
> +					(unsigned long)(o),		\
> +					(unsigned long)(n),		\
> +					sizeof(*(ptr)));		\
> +})
> +#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
> +
>  /*
>   * xchg
>   */
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>