3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: John Stultz <john.stultz@xxxxxxxxxx>
commit 04005f6011e3b504cd4d791d9769f7cb9a3b2eae upstream.
A think-o in the calculation of the monotonic -> tai time offset
results in CLOCK_TAI timers and nanosleeps to expire late (the
latency is ~2x the tai offset).
Fix this by adding the tai offset from the realtime offset instead
of subtracting.
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/time/timekeeping.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -72,7 +72,7 @@ static void tk_set_wall_to_mono(struct t
tk->wall_to_monotonic = wtm;
set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
tk->offs_real = timespec_to_ktime(tmp);
- tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tk->tai_offset, 0));
+ tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0));
}
static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
@@ -590,7 +590,7 @@ s32 timekeeping_get_tai_offset(void)
static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
{
tk->tai_offset = tai_offset;
- tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tai_offset, 0));
+ tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
}
/**
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