linux-kernel - Re: [PATCH 05/33] locking/atomic: openrisc: avoid asm-generic/atomic.h

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Date:   Fri, 14 May 2021 06:44:25 +0900
From:   Stafford Horne <shorne@...il.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, will@...nel.org,
        boqun.feng@...il.com, peterz@...radead.org, aou@...s.berkeley.edu,
        arnd@...db.de, bcain@...eaurora.org, benh@...nel.crashing.org,
        chris@...kel.net, dalias@...c.org, davem@...emloft.net,
        deanbo422@...il.com, deller@....de, geert@...ux-m68k.org,
        green.hu@...il.com, guoren@...nel.org, ink@...assic.park.msu.ru,
        James.Bottomley@...senpartnership.com, jcmvbkbc@...il.com,
        jonas@...thpole.se, ley.foon.tan@...el.com, linux@...linux.org.uk,
        mattst88@...il.com, monstr@...str.eu, mpe@...erman.id.au,
        nickhu@...estech.com, palmer@...belt.com, paulus@...ba.org,
        paul.walmsley@...ive.com, rth@...ddle.net,
        stefan.kristiansson@...nalahti.fi, tsbogend@...ha.franken.de,
        vgupta@...opsys.com, ysato@...rs.sourceforge.jp
Subject: Re: [PATCH 05/33] locking/atomic: openrisc: avoid
 asm-generic/atomic.h

On Mon, May 10, 2021 at 10:37:25AM +0100, Mark Rutland wrote:
> OpenRISC is the only architecture which uses asm-generic/atomic.h and
> also provides its own implementation of some functions, requiring
> ifdeferry in the asm-generic header. As OpenRISC provides the vast
> majority of functions itself, it would be simpler overall if it also
> provided the few functions it cribs from asm-generic.
> 
> This patch decouples OpenRISC from asm-generic/atomic.h. Subsequent
> patches will simplify the asm-generic implementation.

This is fine, but just a thought.  If OpenRISC is the only architecture to do
this then after this patch could we remove the ifndefs from
asm-generic/atomic.h as additional cleanup?

> There should be no functional change as a result of this patch.
> 
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Boqun Feng <boqun.feng@...il.com>
> Cc: Jonas Bonn <jonas@...thpole.se>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Stafford Horne <shorne@...il.com>
> Cc: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
> Cc: Will Deacon <will@...nel.org>
> ---
>  arch/openrisc/include/asm/atomic.h | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/openrisc/include/asm/atomic.h b/arch/openrisc/include/asm/atomic.h
> index b589fac39b92..cb86970d3859 100644
> --- a/arch/openrisc/include/asm/atomic.h
> +++ b/arch/openrisc/include/asm/atomic.h
> @@ -121,6 +121,12 @@ static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
>  }
>  #define atomic_fetch_add_unless	atomic_fetch_add_unless
>  
> -#include <asm-generic/atomic.h>
> +#define atomic_read(v)			READ_ONCE((v)->counter)
> +#define atomic_set(v,i)			WRITE_ONCE((v)->counter, (i))
> +
> +#include <asm/cmpxchg.h>
> +
> +#define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))
> +#define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new)))

Acked-by: Stafford Horne <shorne@...il.com>

>  #endif /* __ASM_OPENRISC_ATOMIC_H */
> -- 
> 2.11.0
>