From: Dean Nelson <dcn@sgi.com>
Message-Id: <200208281459.JAA83371@cyan.americas.sgi.com>
Subject: Re: atomic64_t proposal
To: schwab@suse.de (Andreas Schwab)
Date: Wed, 28 Aug 2002 09:59:54 -0500 (CDT)
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <je1y8kgjda.fsf@sykes.suse.de> from "Andreas Schwab" at Aug 27, 2002 10:02:57 PM
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Andreas Schwab writes:
> 
> Dean Nelson <dcn@sgi.com> writes:
> 
> |> +#define ia64_atomic_add(i,v)						\
> |> +({									\
> |> +	__typeof__((v)->counter) _old, _new;				\
> |> +	CMPXCHG_BUGCHECK_DECL						\
> |> +									\
> |> +	do {								\
> |> +		CMPXCHG_BUGCHECK(v);					\
> |> +		_old = atomic_read(v);					\
> |> +		_new = _old + (i);					\
> |> +	} while (ia64_cmpxchg("acq", (v), _old, _new, sizeof(*(v))) != _old); \
> |> +	(__typeof__((v)->counter)) _new;	/* return new value */	\
> 
> What's the purpose of the cast here? The type of _new is already the
> right one.

You're right, the cast is meaningless and should be removed. It's an artifact
of a macro that had several iterations of development.

> |>  #define atomic_add_return(i,v)						\
> |>  	((__builtin_constant_p(i) &&					\
> |>  	  (   (i ==  1) || (i ==  4) || (i ==  8) || (i ==  16)		\
> |>  	   || (i == -1) || (i == -4) || (i == -8) || (i == -16)))	\
> |>  	 ? ia64_fetch_and_add(i, &(v)->counter)				\
> |> -	 : ia64_atomic_add(i, v))
> |> +	 : ia64_atomic_add((i), (v)))
> 
> The extra parens are useless.

Yep, they're useless. I had introduced them merely to be consistent with
how the other macros in asm-ia64/atomic.h were done (macros that I didn't
modify). But the parentheses can be removed.

Thanks for the corrections.
Dean

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