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Date:      Sun, 13 Jun 2010 12:10:25 +0200
From:      Pawel Jakub Dawidek <pjd@FreeBSD.org>
To:        Lawrence Stewart <lstewart@FreeBSD.org>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org
Subject:   Re: svn commit: r209119 - head/sys/sys
Message-ID:  <20100613101025.GD1320@garage.freebsd.pl>
In-Reply-To: <201006130239.o5D2du3m086332@svn.freebsd.org>
References:  <201006130239.o5D2du3m086332@svn.freebsd.org>

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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
>=20
> Log:
>   Add a utility macro to simplify calculating an aggregate sum from a DPC=
PU
>   counter variable.
>  =20
>   Sponsored by:	FreeBSD Foundation
>   Reviewed by:	jhb, rpaulo, rwatson (previous version of patch)
>   MFC after:	1 week
>=20
> Modified:
>   head/sys/sys/pcpu.h
>=20
> Modified: head/sys/sys/pcpu.h
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- 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) =3D v)
> =20
> +/*
> + * Utility macros.
> + */
> +#define DPCPU_SUM(n, var, sum)						\
> +do {									\
> +	(sum) =3D 0;							\
> +	u_int i;							\
> +	CPU_FOREACH(i)							\
> +		(sum) +=3D (DPCPU_ID_PTR(i, n))->var;			\
> +} while (0)

I'd suggest first swapping variable declaration and '(sum) =3D 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?

--=20
Pawel Jakub Dawidek                       http://www.wheelsystems.com
pjd@FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!

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