* [PATCH] lib: gcd: prevent possible div by 0
@ 2012-09-09 15:03 Davidlohr Bueso
2012-09-10 9:12 ` Eric Dumazet
0 siblings, 1 reply; 3+ messages in thread
From: Davidlohr Bueso @ 2012-09-09 15:03 UTC (permalink / raw)
To: lkml, Andrew Morton; +Cc: stable
Account for properties when a and/or b are 0:
gcd(0, 0) = 0
gcd(a, 0) = a
gcd(0, b) = b
Cc: stable@vger.kernel.org
Signed-off-by: Davidlohr Bueso <dave@gnu.org>
---
lib/gcd.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/lib/gcd.c b/lib/gcd.c
index cce4f3c..7e163c6 100644
--- a/lib/gcd.c
+++ b/lib/gcd.c
@@ -7,6 +7,9 @@ unsigned long gcd(unsigned long a, unsigned long b)
{
unsigned long r;
+ if (!a || !b)
+ return a | b;
+
if (a < b)
swap(a, b);
while ((r = a % b) != 0) {
--
1.7.9.5
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] lib: gcd: prevent possible div by 0
2012-09-09 15:03 [PATCH] lib: gcd: prevent possible div by 0 Davidlohr Bueso
@ 2012-09-10 9:12 ` Eric Dumazet
2012-09-10 10:30 ` Davidlohr Bueso
0 siblings, 1 reply; 3+ messages in thread
From: Eric Dumazet @ 2012-09-10 9:12 UTC (permalink / raw)
To: dave; +Cc: lkml, Andrew Morton, stable
On Sun, 2012-09-09 at 17:03 +0200, Davidlohr Bueso wrote:
> Account for properties when a and/or b are 0:
> gcd(0, 0) = 0
> gcd(a, 0) = a
> gcd(0, b) = b
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Davidlohr Bueso <dave@gnu.org>
> ---
> lib/gcd.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/lib/gcd.c b/lib/gcd.c
> index cce4f3c..7e163c6 100644
> --- a/lib/gcd.c
> +++ b/lib/gcd.c
> @@ -7,6 +7,9 @@ unsigned long gcd(unsigned long a, unsigned long b)
> {
> unsigned long r;
>
> + if (!a || !b)
> + return a | b;
This seems overkill
> +
> if (a < b)
> swap(a, b);
better here to :
if (!b)
return a;
> while ((r = a % b) != 0) {
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] lib: gcd: prevent possible div by 0
2012-09-10 9:12 ` Eric Dumazet
@ 2012-09-10 10:30 ` Davidlohr Bueso
0 siblings, 0 replies; 3+ messages in thread
From: Davidlohr Bueso @ 2012-09-10 10:30 UTC (permalink / raw)
To: Eric Dumazet; +Cc: lkml, Andrew Morton, stable
On Mon, 2012-09-10 at 11:12 +0200, Eric Dumazet wrote:
> On Sun, 2012-09-09 at 17:03 +0200, Davidlohr Bueso wrote:
> > Account for properties when a and/or b are 0:
> > gcd(0, 0) = 0
> > gcd(a, 0) = a
> > gcd(0, b) = b
> >
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Davidlohr Bueso <dave@gnu.org>
> > ---
> > lib/gcd.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/lib/gcd.c b/lib/gcd.c
> > index cce4f3c..7e163c6 100644
> > --- a/lib/gcd.c
> > +++ b/lib/gcd.c
> > @@ -7,6 +7,9 @@ unsigned long gcd(unsigned long a, unsigned long b)
> > {
> > unsigned long r;
> >
> > + if (!a || !b)
> > + return a | b;
>
> This seems overkill
It might, but it reads better, IMHO.
>
> > +
> > if (a < b)
> > swap(a, b);
>
> better here to :
> if (!b)
> return a;
>
Sure, I don't mind either way. I'll send a v2 shortly.
Thanks for reviewing.
Davidlohr
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-09-10 9:12 ` Eric Dumazet
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