Messages in this thread | | | From | Ondrej Mosnacek <> | Date | Wed, 17 Apr 2019 11:00:23 +0200 | Subject | Re: [PATCH] ntp: Allow TAI-UTC offset to be set to zero |
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On Wed, Apr 17, 2019 at 10:48 AM Miroslav Lichvar <mlichvar@redhat.com> wrote: > The ADJ_TAI adjtimex mode sets the TAI-UTC offset of the system clock. > It is typically set by NTP/PTP implementations and it is automatically > updated by the kernel on leap seconds. The initial value is zero (which > applications may interpret as unknown), but this value cannot be set by > adjtimex. This limitation seems to go back to the original "nanokernel" > implementation by David Mills. > > Change the ADJ_TAI check to accept zero as a valid TAI-UTC offset in > order to allow setting it back to the initial value. > > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Richard Cochran <richardcochran@gmail.com> > Cc: Prarit Bhargava <prarit@redhat.com> > Suggested-by: Ondrej Mosnacek <omosnace@redhat.com> > Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Thanks for sending the patch! Maybe you (or the committer) could consider adding:
Fixes: 153b5d054ac2 ("ntp: support for TAI")
so that it gets to the stable kernels as well.
> --- > kernel/time/ntp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c > index 92a90014a925..f43d47c8c3b6 100644 > --- a/kernel/time/ntp.c > +++ b/kernel/time/ntp.c > @@ -690,7 +690,7 @@ static inline void process_adjtimex_modes(const struct __kernel_timex *txc, > time_constant = max(time_constant, 0l); > } > > - if (txc->modes & ADJ_TAI && txc->constant > 0) > + if (txc->modes & ADJ_TAI && txc->constant >= 0) > *time_tai = txc->constant; > > if (txc->modes & ADJ_OFFSET) > -- > 2.17.2
-- Ondrej Mosnacek <omosnace at redhat dot com> Software Engineer, Security Technologies Red Hat, Inc.
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