* John Stultz <john.stu...@linaro.org> wrote:
> When we make adjustments speeding up the clock, its possible
> for xtime_nsec to underflow. We already handle this properly,
> but we do so from update_wall_time() instead of the more logical
> timekeeping_adjust(), where the possible underflow actually
> occurs.
>
> Thus, move the correction logic to the timekeeping_adjust, which
> is the function that causes the issue. Making update_wall_time()
> more readable.
>
> CC: Ingo Molnar <mi...@kernel.org>
> CC: Peter Zijlstra <a.p.zijls...@chello.nl>
> CC: Richard Cochran <richardcoch...@gmail.com>
> CC: Prarit Bhargava <pra...@redhat.com>
> CC: Thomas Gleixner <t...@linutronix.de>
> Signed-off-by: John Stultz <johns...@us.ibm.com>
> ---
> kernel/time/timekeeping.c | 42 +++++++++++++++++++++---------------------
> 1 file changed, 21 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index dd119355..4b76432 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -987,6 +987,27 @@ static void timekeeping_adjust(s64 offset)
> timekeeper.xtime_nsec -= offset;
> timekeeper.ntp_error -= (interval - offset) <<
> timekeeper.ntp_error_shift;
> +
> + /*
> + * It may be possible that when we entered this function, xtime_nsec
> + * was very small. Further, if we're slightly speeding the clocksource
> + * in the code above, its possible the required corrective factor to
> + * xtime_nsec could cause it to underflow.
s/slightly speeding/slightly speeding up ?
> + *
> + * Now, since we already accumulated the second, cannot simply roll
> + * the accumulated second back, since the NTP subsystem has been
s/cannot/we cannot ?
Thanks,
Ingo
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