From 832609cc5f16a955648880ebc69b8f226f8782bb Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" 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 -- 2.7.4