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authorIngo Molnar <mingo@elte.hu>2009-02-22 13:38:40 +0100
committerIngo Molnar <mingo@elte.hu>2009-02-25 18:38:13 +0100
commit10dd31a7a17254d6ba793305fc590455393e610e (patch)
tree7416cf325f40eb27df6f0455807a0a1dfb203c2d
parentc7986acba211e8285e14c9603fb89e6f4ea0b9f8 (diff)
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 <mingo@elte.hu>
-rw-r--r--kernel/time/ntp.c9
1 files changed, 8 insertions, 1 deletions
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) {