From 10dd31a7a17254d6ba793305fc590455393e610e Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 22 Feb 2009 13:38:40 +0100 Subject: time: ntp: fix bug in ntp_update_offset() & do_adjtimex() Impact: change (fix) the way the NTP PLL seconds offset is initialized/tracked Fix a bug and do a micro-optimization: When PLL is enabled we do not reset time_reftime. If the PLL was off for a long time (for example after bootup), this is arguably the wrong thing to do. We already had a hack for the common boot-time case in ntp_update_offset(), in form of: if (unlikely(time_status & STA_FREQHOLD || time_reftime == 0)) secs = 0; But the update delta should be reset later on too - not just when the PLL is enabled for the first time after bootup. So do it on !STA_PLL -> STA_PLL transitions. This changes behavior, as previously if ntpd was disabled for a long time and we restarted it, we'd run from that last update, with a very large delta. Signed-off-by: Ingo Molnar --- kernel/time/ntp.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'kernel/time/ntp.c') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 580a3502869..fc08eb10ced 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -142,7 +142,7 @@ static void ntp_update_offset(long offset) * and in which mode (PLL or FLL). */ secs = xtime.tv_sec - time_reftime; - if (unlikely(time_status & STA_FREQHOLD || time_reftime == 0)) + if (unlikely(time_status & STA_FREQHOLD)) secs = 0; time_reftime = xtime.tv_sec; @@ -394,6 +394,13 @@ int do_adjtimex(struct timex *txc) } /* only set allowed bits */ time_status &= STA_RONLY; + /* + * If we turn on PLL adjustments then reset the + * reference time to current time. + */ + if (!(time_status & STA_PLL) && (txc->status & STA_PLL)) + time_reftime = xtime.tv_sec; + time_status |= txc->status & ~STA_RONLY; switch (time_state) { -- cgit v1.2.3