Re: [PATCH v2 1/2] linux/kernel.h: Introduce IDIV_ROUND_CLOSEST

From: Guenter Roeck
Date: Thu Aug 30 2012 - 19:50:16 EST


On Thu, Aug 30, 2012 at 04:15:32PM -0700, Andrew Morton wrote:
> On Tue, 28 Aug 2012 09:30:55 -0700
> Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> > DIV_ROUND_CLOSEST returns a bad result for negative dividends:
> > DIV_ROUND_CLOSEST(-2, 2) = 0
> >
> > Most of the time this does not matter. However, in the hardware monitoring
> > subsystem, it is sometimes used on integers which can be negative (such as
> > temperatures). Introduce new macro IDIV_ROUND_CLOSEST which also supports
> > negative dividends.
> >
>
> Can't we just fix DIV_ROUND_CLOSEST? That will make it a bit slower
> but it's not exactly a speed demon right now. And fixing
> DIV_ROUND_CLOSEST() might just fix other bugs that we don't know about
> yet.
>
Sure, fine with me. I'll submit a patch. Let's see who starts screaming.

Guenter
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