[tip:timers/core] timekeeping: Fix invalid getboottime() value

[tip-bot for Hiroshi Shimamoto]

Commit-ID:  36d47481b3824b661b464077db95d447984df799
Gitweb:     http://git.kernel.org/tip/36d47481b3824b661b464077db95d447984df799
Author:     Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>
AuthorDate: Tue, 25 Aug 2009 15:08:30 +0900
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 25 Aug 2009 09:09:02 +0200

timekeeping: Fix invalid getboottime() value

Don't use timespec_add_safe() with wall_to_monotonic, because
wall_to_monotonic has negative values which will cause overflow
in timespec_add_safe(). That makes btime in /proc/stat invalid.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: John Stultz <johnstul@xxxxxxxxxx>
Cc: Daniel Walker <dwalker@xxxxxxxxxx>
LKML-Reference: <4A937FDE.4050506@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 kernel/time/timekeeping.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 03cbeb3..fb0f46f 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -826,9 +826,11 @@ void update_wall_time(void)
  */
 void getboottime(struct timespec *ts)
 {
-	struct timespec boottime;
+	struct timespec boottime = {
+		.tv_sec = wall_to_monotonic.tv_sec + total_sleep_time.tv_sec,
+		.tv_nsec = wall_to_monotonic.tv_nsec + total_sleep_time.tv_nsec
+	};
 
-	boottime = timespec_add_safe(wall_to_monotonic, total_sleep_time);
 	set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
 }
 
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