From 832609cc5f16a955648880ebc69b8f226f8782bb Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Sat, 14 May 2016 19:22:49 +0100

Subject: [PATCH] utils: boot-analysis: Avoid overflow when comparing large

 doubles.

(cherry picked from commit 1f4a0bd90df35df56eb86c2386d801b51828cb22)

---

 utils/boot-analysis/boot-analysis.c | 11 ++++++++++-

 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/utils/boot-analysis/boot-analysis.c b/utils/boot-analysis/boot-analysis.c

index 3690ed4..d06d9a1 100644

--- a/utils/boot-analysis/boot-analysis.c

+++ b/utils/boot-analysis/boot-analysis.c

@@ -1157,7 +1157,16 @@ compare_activities_pointers_by_mean (const void *av, const void *bv)

   assert ((*a)->magic == ACTIVITY_MAGIC);

   assert ((*b)->magic == ACTIVITY_MAGIC);

-  return (*b)->mean - (*a)->mean;

+

+  /* The mean field is a double in nanoseconds.  For the result of the

+   * comparison we want an integer.  If it is larger than around 2^32,

+   * the following will produce an incorrect result.  Therefore we use

+   * this trick.  Note we want to return largest first.

+   */

+  double a_mean = (*a)->mean;

+  double b_mean = (*b)->mean;

+

+  return (b_mean > a_mean) - (b_mean < a_mean);

 }

 static void

-- 

1.8.3.1