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

From: Stafford Horne <shorne@gmail.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org, will@kernel.org,
	boqun.feng@gmail.com, peterz@infradead.org,
	aou@eecs.berkeley.edu, arnd@arndb.de, bcain@codeaurora.org,
	benh@kernel.crashing.org, chris@zankel.net, dalias@libc.org,
	davem@davemloft.net, deanbo422@gmail.com, deller@gmx.de,
	geert@linux-m68k.org, green.hu@gmail.com, guoren@kernel.org,
	ink@jurassic.park.msu.ru, James.Bottomley@hansenpartnership.com,
	jcmvbkbc@gmail.com, jonas@southpole.se, ley.foon.tan@intel.com,
	linux@armlinux.org.uk, mattst88@gmail.com, monstr@monstr.eu,
	mpe@ellerman.id.au, nickhu@andestech.com, palmer@dabbelt.com,
	paulus@samba.org, paul.walmsley@sifive.com, rth@twiddle.net,
	stefan.kristiansson@saunalahti.fi, tsbogend@alpha.franken.de,
	vgupta@synopsys.com, ysato@users.sourceforge.jp
Subject: Re: [PATCH 05/33] locking/atomic: openrisc: avoid asm-generic/atomic.h
Date: Fri, 14 May 2021 06:44:25 +0900	[thread overview]
Message-ID: <YJ2dud8alZgKmiQ3@antec> (raw)
In-Reply-To: <20210510093753.40683-6-mark.rutland@arm.com>

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@arm.com>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Jonas Bonn <jonas@southpole.se>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Stafford Horne <shorne@gmail.com>
> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
> Cc: Will Deacon <will@kernel.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@gmail.com>

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