From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Wed, 10 Dec 2014 23:51:27 +0000 (-0800)
Subject: lib/lcm.c: ensure correct result whenever it fits
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=74a5fef7cb0839c6b595f90c7914a62ac9d0bcf9;p=openwrt%2Fstaging%2Fblogic.git

lib/lcm.c: ensure correct result whenever it fits

Ensure that lcm(a,b) returns the mathematically correct result, provided
it fits in an unsigned long.  The current version returns garbage if a*b
overflows, even if the final result would fit.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/lib/lcm.c b/lib/lcm.c
index b9c8de461e9e..01b3aa922dda 100644
--- a/lib/lcm.c
+++ b/lib/lcm.c
@@ -7,7 +7,7 @@
 unsigned long lcm(unsigned long a, unsigned long b)
 {
 	if (a && b)
-		return (a * b) / gcd(a, b);
+		return (a / gcd(a, b)) * b;
 	else if (b)
 		return b;