After calling adjfreq to correct the clock's rate, measure and fix the clock

offset. This avoids future frequency adjustments based on measurements of a
clock that was being adjusted. End result: more stable clock and better
frequency convergence.
Also, fix a mis-ordered structure member while I'm here.
ok henning

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.110 2009/01/26 11:51:50 henning Exp $ */
+/*	$OpenBSD: ntp.c,v 1.111 2009/06/04 23:39:45 ckuethe Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -530,6 +530,11 @@ priv_adjfreq(double offset)
 	if (!conf->status.synced)
 		return;
 
+	if (conf->filters & FILTER_ADJFREQ){
+		conf->filters &= ~FILTER_ADJFREQ;
+		return;
+	}
+
 	conf->freq.samples++;
 
 	if (conf->freq.samples <= 0)
@@ -558,6 +563,7 @@ priv_adjfreq(double offset)
 		freq = -MAX_FREQUENCY_ADJUST;
 
 	imsg_compose(ibuf_main, IMSG_ADJFREQ, 0, 0, &freq, sizeof(freq));
+	conf->filters |= FILTER_ADJFREQ;
 	conf->freq.xy = 0.0;
 	conf->freq.x = 0.0;
 	conf->freq.y = 0.0;

src/usr.sbin/ntpd/ntpd.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntpd.h,v 1.100 2009/05/13 15:08:10 stevesk Exp $ */
+/*	$OpenBSD: ntpd.h,v 1.101 2009/06/04 23:39:46 ckuethe Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -62,6 +62,7 @@
 #define REPORT_INTERVAL		(24*60*60) /* interval between status reports */
 #define MAX_SEND_ERRORS		3	/* max send errors before reconnect */
 
+#define FILTER_ADJFREQ		0x01	/* set after doing adjfreq */
 
 #define	SENSOR_DATA_MAXAGE		(15*60)
 #define	SENSOR_QUERY_INTERVAL		30
@@ -171,11 +172,12 @@ struct ntpd_conf {
 	TAILQ_HEAD(ntp_conf_sensors, ntp_conf_sensor)	ntp_conf_sensors;
 	struct ntp_status				status;
 	struct ntp_freq					freq;
+	u_int32_t					scale;
 	u_int8_t					listen_all;
 	u_int8_t					settime;
 	u_int8_t					debug;
-	u_int32_t					scale;
 	u_int8_t					noaction;
+	u_int8_t					filters;
 };
 
 struct buf {