linux-kernel - Re: [PATCH 1/8] add lib/gcd.c

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Message-Id: <20090604120340.079f6cdf.akpm@linux-foundation.org>
Date:	Thu, 4 Jun 2009 12:03:40 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Florian Fainelli <florian@...nwrt.org>,
	Sergei Shtylyov <sshtylyov@...mvista.com>,
	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	Linux-MIPS <linux-mips@...ux-mips.org>,
	linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>,
	Ralf Baechle <ralf@...ux-mips.org>
Subject: Re: [PATCH 1/8] add lib/gcd.c

On Thu, 04 Jun 2009 08:57:24 -0700 Joe Perches <joe@...ches.com> wrote:

> On Thu, 2009-06-04 at 16:39 +0200, Florian Fainelli wrote:
> > diff --git a/lib/gcd.c b/lib/gcd.c
> > new file mode 100644
> > index 0000000..6634741
> > --- /dev/null
> > +++ b/lib/gcd.c
> > @@ -0,0 +1,20 @@
> > +#include <linux/gcd.h>
> > +#include <linux/module.h>
> > +
> > +/* Greatest common divisor */
> > +unsigned long gcd(unsigned long a, unsigned long b)
> > +{
> > +	unsigned long r;
> > +
> > +	if (a < b) {
> > +		r = a;
> > +		a = b;
> > +		b = r;
> 	swap(a, b)

yup

> > +	}
> > +	while ((r = a % b) != 0) {
> > +		a = b;
> > +		b = r;
> > +	}
> > +	return b;
> > +}
> > +EXPORT_SYMBOL_GPL(gcd);
> 
> Shouldn't a generic gcd protect against a div0
> if gcd(0,0)?

nope.  It's a caller bug, there's nothing the callee can do to fix it,
so an oops is a fine response.

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