From: Dave Hart <hart@ntp.org>
Date: Tue, 20 Sep 2011 01:32:36 +0000 (+0000)
Subject: [Bug 2009] EVNT_NSET adj_systime() mishandled by Windows ntpd.
X-Git-Tag: NTP_4_2_7P214~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02ea9cfd446d88555bd4449841eb2d821610dc16;p=thirdparty%2Fntp.git

[Bug 2009] EVNT_NSET adj_systime() mishandled by Windows ntpd.

bk: 4e77ed340mOubTK4uXdZNY3RlM_Gaw
---

diff --git a/ChangeLog b/ChangeLog
index 2aa951266..5d99da973 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 * [Bug 1981] Initial offset convergence applies frequency correction 2x
   with kernel discipline.
 * [Bug 2008] Initial offset convergence degraded with 500 PPM adjtime().
+* [Bug 2009] EVNT_NSET adj_systime() mishandled by Windows ntpd.
 (4.2.7p213) 2011/09/08 Released by Harlan Stenn <stenn@ntp.org>
 * [Bug 1999] NMEA does not send PMOTG messages any more.
 (4.2.7p212) 2011/09/07 Released by Harlan Stenn <stenn@ntp.org>
diff --git a/ports/winnt/ntpd/nt_clockstuff.c b/ports/winnt/ntpd/nt_clockstuff.c
index 3036e835e..e1c93dabf 100644
--- a/ports/winnt/ntpd/nt_clockstuff.c
+++ b/ports/winnt/ntpd/nt_clockstuff.c
@@ -406,7 +406,14 @@ set_mm_timer(
 }
 
 /*
- * adj_systime - called once every second to make system time adjustments.
+ * adj_systime - called once every second to discipline system clock.
+ * Normally, the offset passed in (parameter now) is in the range
+ * [-NTP_MAXFREQ, NTP_MAXFREQ].  However, at EVNT_NSET, a much larger
+ * slew is requested if the initial offset is less than the step
+ * threshold, in the range [-step, step] where step is the step
+ * threshold, 128 msec by default.  For the remainder of the frequency
+ * training interval, adj_systime is called with 0 offset each second
+ * and slew the large offset at 500 PPM (500 usec/sec).
  * Returns 1 if okay, 0 if trouble.
  */
 int
@@ -414,20 +421,22 @@ adj_systime(
 	double now
 	)
 {
-	double dtemp;
-	u_char isneg;
-	BOOL rc;
-	long TimeAdjustment;
-	SYSTEMTIME st;
-	ULONGLONG this_perf_count;
-	FT_ULL curr_ft;
+	static double	adjtime_carry;
+	double		dtemp;
+	u_char		isneg;
+	BOOL		rc;
+	long		TimeAdjustment;
+	SYSTEMTIME	st;
+	ULONGLONG	this_perf_count;
+	FT_ULL		curr_ft;
 
 	/*
 	 * Add the residual from the previous adjustment to the new
 	 * adjustment, bound and round.
 	 */
-	dtemp = sys_residual + now;
-	sys_residual = 0;
+	dtemp = adjtime_carry + sys_residual + now;
+	adjtime_carry = 0.;
+	sys_residual = 0.;
 	if (dtemp < 0) {
 		isneg = TRUE;
 		dtemp = -dtemp;
@@ -435,13 +444,17 @@ adj_systime(
 		isneg = FALSE;
 	}
 
-	if (dtemp > NTP_MAXFREQ)
+	if (dtemp > NTP_MAXFREQ) {
+		adjtime_carry = dtemp - NTP_MAXFREQ;
 		dtemp = NTP_MAXFREQ;
+	}
 
-	dtemp = dtemp * 1e6;
-
-	if (isneg)
+	if (isneg) {
 		dtemp = -dtemp;
+		adjtime_carry = -adjtime_carry;
+	}
+
+	dtemp = dtemp * 1e6;
 
 	/* 
 	 * dtemp is in micro seconds. NT uses 100 ns units,
@@ -545,11 +558,16 @@ adj_systime(
 	}
 
 
+	sys_residual = dtemp / 1e6;
+	DPRINTF(3, ("adj_systime: %.9f -> %.9f residual %.9f adjtime %.9f\n", 
+		    now, 1e-6 * (TimeAdjustment * ppm_per_adjust_unit),
+		    sys_residual, adjtime_carry));
+
 	/* only adjust the clock if adjustment changes */
 	TimeAdjustment += wintickadj;
 	if (last_Adj != TimeAdjustment) {
 		last_Adj = TimeAdjustment;
-		DPRINTF(1, ("SetSystemTimeAdjustment(%+ld)\n", TimeAdjustment));
+		DPRINTF(2, ("SetSystemTimeAdjustment(%+ld)\n", TimeAdjustment));
 		rc = !SetSystemTimeAdjustment(clockperiod + TimeAdjustment, FALSE);
 	} else {
 		rc = FALSE;
@@ -559,10 +577,6 @@ adj_systime(
 		return FALSE;
 	}
 
-	sys_residual = dtemp / 1e6;
-	DPRINTF(4, ("adj_systime: adj %.9f -> remaining residual %.9f\n", 
-		    now, sys_residual));
-
 	return TRUE;
 }