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Message-Id: <20140211184751.134673978@linuxfoundation.org>
Date: Tue, 11 Feb 2014 11:06:09 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Prarit Bhargava <prarit@...hat.com>,
Richard Cochran <richardcochran@...il.com>,
Ingo Molnar <mingo@...nel.org>,
John Stultz <john.stultz@...aro.org>
Subject: [PATCH 3.12 103/107] timekeeping: Fix CLOCK_TAI timer/nanosleep delays
3.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: John Stultz <john.stultz@...aro.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@...cle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Richard Cochran <richardcochran@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: John Stultz <john.stultz@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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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