summaryrefslogtreecommitdiff
path: root/include
diff options
context:
space:
mode:
authorJohn Stultz <john.stultz@linaro.org>2017-06-08 16:44:21 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-26 08:49:00 +0200
commit09f7ebaa436c9bdad4a21c24fed5057604e709c1 (patch)
tree2ac9a8e752d7a75b4f80f72948acb538461833ed /include
parent92cffdc98efb1dea5d6f6911616f05dc6338d75f (diff)
time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting
commit 3d88d56c5873f6eebe23e05c3da701960146b801 upstream. 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> [fabrizio: cherry-pick to 4.4. Kept cycle_t type for function logarithmic_accumulation local variable "interval". Dropped casting of "interval" variable] Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com> Signed-off-by: Biju Das <biju.das@bp.renesas.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/timekeeper_internal.h4
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