[PATCH] Fix half-Y2K38 problem in timecompare_update while calculating offset

[Barry Song]

ktime will overflow from 03:14:07 UTC on Tuesday, 19 January 2038,
ktime_add() in timecompare_update() will overflow a half earlier.
As a result, wrong offset will be gotten, then cause some strange
problems.
---
 kernel/time/timecompare.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/time/timecompare.c b/kernel/time/timecompare.c
index 71e7f1a..d2d893e 100644
--- a/kernel/time/timecompare.c
+++ b/kernel/time/timecompare.c
@@ -89,7 +89,7 @@ int timecompare_offset(struct timecompare *sync,
 			 * source time
 			 */
 			sample.offset =
-				ktime_to_ns(ktime_add(end, start)) / 2 -
+				(ktime_to_ns(end) + ktime_to_ns(start)) / 2 -
 				ts;
 
 			/* simple insertion sort based on duration */
-- 
1.5.6.3

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