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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [patch 2/2] powerpc: optimise smp_wmb
Date: Wed, 21 May 2008 22:16:31 +0200
To: Nick Piggin <npiggin@suse.de>
Cc: linuxppc-dev@ozlabs.org, paulus@samba.org
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> +#ifdef __SUBARCH_HAS_LWSYNC
> +#    define SMPWMB      lwsync
> +#else
> +#    define SMPWMB      eieio
> +#endif
> +
>  #define smp_mb()	mb()
>  #define smp_rmb()	rmb()
> -#define smp_wmb()	eieio()
> +#define smp_wmb()	__asm__ __volatile__ (__stringify(SMPWMB) : : 
> :"memory")

SMPWMB is used only here.  Why not just

#ifdef __SUBARCH_HAS_LWSYNC
#define smp_wmb() lwsync()
#else
#define smp_wmb() eieio()
#endif

?


Segher