diff options
| author | John Stultz <john.stultz@linaro.org> | 2017-06-08 16:44:21 -0700 |
|---|---|---|
| committer | Mark Salyzyn <salyzyn@google.com> | 2017-11-29 13:35:07 -0800 |
| commit | 28850c79d071b4eef0001bb76af2cfb29402f4ac (patch) | |
| tree | c4afbe8bb14fc8d082fc0c033689de50f83326eb /include | |
| parent | 67a8ab4adc2d30e3f3442a0659b887b4da83f7c2 (diff) | |
BACKPORT: time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting
(cherry pick from commit 3d88d56c5873f6eebe23e05c3da701960146b801)
Due to how the MONOTONIC_RAW accumulation logic was handled,
there is the potential for a 1ns discontinuity when we do
accumulations. This small discontinuity has for the most part
gone un-noticed, but since ARM64 enabled CLOCK_MONOTONIC_RAW
in their vDSO clock_gettime implementation, we've seen failures
with the inconsistency-check test in kselftest.
This patch addresses the issue by using the same sub-ns
accumulation handling that CLOCK_MONOTONIC uses, which avoids
the issue for in-kernel users.
Since the ARM64 vDSO implementation has its own clock_gettime
calculation logic, this patch reduces the frequency of errors,
but failures are still seen. The ARM64 vDSO will need to be
updated to include the sub-nanosecond xtime_nsec values in its
calculation for this issue to be completely fixed.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Tested-by: Daniel Mentz <danielmentz@google.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: "stable #4 . 8+" <stable@vger.kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Link: http://lkml.kernel.org/r/1496965462-20003-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Bug: 20045882
Bug: 63737556
Change-Id: I6c55dd7685f6bd212c6af9d09c527528e1dd5fa1
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/timekeeper_internal.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index f0f1793cfa49..115216ec7cfe 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -56,7 +56,7 @@ struct tk_read_base { * interval. * @xtime_remainder: Shifted nano seconds left over when rounding * @cycle_interval - * @raw_interval: Raw nano seconds accumulated per NTP interval. + * @raw_interval: Shifted raw nano seconds accumulated per NTP interval. * @ntp_error: Difference between accumulated time and NTP time in ntp * shifted nano seconds. * @ntp_error_shift: Shift conversion between clock shifted nano seconds and @@ -97,7 +97,7 @@ struct timekeeper { cycle_t cycle_interval; u64 xtime_interval; s64 xtime_remainder; - u32 raw_interval; + u64 raw_interval; /* The ntp_tick_length() value currently being used. * This cached copy ensures we consistently apply the tick * length for an entire tick, as ntp_tick_length may change |