linux-kernel - Re: [PATCH 22/37] move round

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Message-ID: <alpine.DEB.2.00.1001191155540.22304@router.home>
Date:	Tue, 19 Jan 2010 11:57:15 -0600 (CST)
From:	Christoph Lameter <cl@...ux-foundation.org>
To:	Yinghai Lu <yinghai@...nel.org>
cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 22/37] move round_up/down to kernel.h

On Fri, 15 Jan 2010, Yinghai Lu wrote:

>
>  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>
> +/*
> + * This looks more complex than it should be. But we need to
> + * get the type for the ~ right in round_down (it needs to be
> + * as wide as the result!), and we want to evaluate the macro
> + * arguments just once each.
> + */
> +#define __round_mask(x,y) ((__typeof__(x))((y)-1))
> +#define round_up(x,y) ((((x)-1) | __round_mask(x,y))+1)
> +#define round_down(x,y) ((x) & ~__round_mask(x,y))
> +
>  #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
>  #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
>  #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))

Note the last two lines! We already have roundup(), DIV_ROUND_UP and
DIV_ROUND_CLOSEST. Please integrate them properly. Maybe extract
__round_mask() from all of them.

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