| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.12 103/107] timekeeping: Fix CLOCK_TAI timer/nanosleep delays | Date | Tue, 11 Feb 2014 11:06:09 -0800 |
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3.12-stable review patch. If anyone has any objections, please let me know.
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From: John Stultz <john.stultz@linaro.org>
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@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/time/timekeeping.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -77,7 +77,7 @@ 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) @@ -595,7 +595,7 @@ 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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