svn commit: r209119 - head/sys/sys

[Pawel Jakub Dawidek]

On Sun, Jun 13, 2010 at 02:39:55AM +0000, Lawrence Stewart wrote:
> Author: lstewart
> Date: Sun Jun 13 02:39:55 2010
> New Revision: 209119
> URL: http://svn.freebsd.org/changeset/base/209119
> 
> Log:
>   Add a utility macro to simplify calculating an aggregate sum from a DPCPU
>   counter variable.
>   
>   Sponsored by:	FreeBSD Foundation
>   Reviewed by:	jhb, rpaulo, rwatson (previous version of patch)
>   MFC after:	1 week
> 
> Modified:
>   head/sys/sys/pcpu.h
> 
> Modified: head/sys/sys/pcpu.h
> ==============================================================================
> --- head/sys/sys/pcpu.h	Sun Jun 13 01:27:29 2010	(r209118)
> +++ head/sys/sys/pcpu.h	Sun Jun 13 02:39:55 2010	(r209119)
> @@ -106,6 +106,17 @@ extern uintptr_t dpcpu_off[];
>  #define	DPCPU_ID_GET(i, n)	(*DPCPU_ID_PTR(i, n))
>  #define	DPCPU_ID_SET(i, n, v)	(*DPCPU_ID_PTR(i, n) = v)
>  
> +/*
> + * Utility macros.
> + */
> +#define DPCPU_SUM(n, var, sum)						\
> +do {									\
> +	(sum) = 0;							\
> +	u_int i;							\
> +	CPU_FOREACH(i)							\
> +		(sum) += (DPCPU_ID_PTR(i, n))->var;			\
> +} while (0)

I'd suggest first swapping variable declaration and '(sum) = 0;'.
Also using 'i' as a counter in macro can easly lead to name collision.
If you need to do it, I'd suggest '_i' or something.
Maybe it would be better to make it an inline function rather than macro?

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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