| From 04005f6011e3b504cd4d791d9769f7cb9a3b2eae Mon Sep 17 00:00:00 2001 |
| From: John Stultz <john.stultz@linaro.org> |
| Date: Tue, 10 Dec 2013 17:13:35 -0800 |
| Subject: timekeeping: Fix CLOCK_TAI timer/nanosleep delays |
| |
| 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 |
| @@ -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)); |
| } |
| |
| /** |
