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
p...@freebsd.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!

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