Simplyfy adjtime(2) by keeping track of the adjustment as a number of

microsecond in a 64-bit integer.  Fixes the issue where ntpd loses sync
because the struct timeval currently used to hold the adjustment is not
properly normalized after the changes guenther@ made.

ok guenther@, millert@

3 files changed, 30 insertions, 38 deletions

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index 241aaa9e080..4d112aa4966 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -6,7 +6,7 @@
  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
  * ----------------------------------------------------------------------------
  *
- * $OpenBSD: kern_tc.c,v 1.21 2013/10/06 01:27:49 guenther Exp $
+ * $OpenBSD: kern_tc.c,v 1.22 2014/01/30 21:01:59 kettenis Exp $
  * $FreeBSD: src/sys/kern/kern_tc.c,v 1.148 2003/03/18 08:45:23 phk Exp $
  */
 
@@ -611,20 +611,15 @@ sysctl_tc(int *name, u_int namelen, void *oldp, size_t *oldlenp,
 void
 ntp_update_second(int64_t *adjust, time_t *sec)
 {
-	struct timeval adj;
+	int64_t adj;
 
 	/* Skew time according to any adjtime(2) adjustments. */
-	timerclear(&adj);
-	if (adjtimedelta.tv_sec > 0)
-		adj.tv_usec = 5000;
-	else if (adjtimedelta.tv_sec == 0)
-		adj.tv_usec = MIN(5000, adjtimedelta.tv_usec);
-	else if (adjtimedelta.tv_sec < -1)
-		adj.tv_usec = -5000;
-	else if (adjtimedelta.tv_sec == -1)
-		adj.tv_usec = MAX(-5000, adjtimedelta.tv_usec - 1000000);
-	timersub(&adjtimedelta, &adj, &adjtimedelta);
-	*adjust = ((int64_t)adj.tv_usec * 1000) << 32;
+	if (adjtimedelta > 0)
+		adj = MIN(5000, adjtimedelta);
+	else
+		adj = MAX(-5000, adjtimedelta);
+	adjtimedelta -= adj;
+	*adjust = (adj * 1000) << 32;
 	*adjust += timecounter->tc_freq_adj;
 }
 
diff --git a/sys/kern/kern_time.c b/sys/kern/kern_time.c
index 858d860b50f..f48c3a2af86 100644
--- a/sys/kern/kern_time.c
+++ b/sys/kern/kern_time.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_time.c,v 1.86 2014/01/22 00:48:36 guenther Exp $	*/
+/*	$OpenBSD: kern_time.c,v 1.87 2014/01/30 21:01:59 kettenis Exp $	*/
 /*	$NetBSD: kern_time.c,v 1.20 1996/02/18 11:57:06 fvdl Exp $	*/
 
 /*
@@ -46,7 +46,7 @@
 #include <sys/syscallargs.h>
 
 
-struct timeval adjtimedelta;		/* unapplied time correction */
+int64_t adjtimedelta;		/* unapplied time correction (microseconds) */
 
 /* 
  * Time of day and interval timer support.
@@ -68,8 +68,7 @@ settime(struct timespec *ts)
 	 * Adjtime in progress is meaningless or harmful after
 	 * setting the clock. Cancel adjtime and then set new time.
 	 */
-	adjtimedelta.tv_usec = 0;
-	adjtimedelta.tv_sec = 0;
+	adjtimedelta = 0;
 
 	/*
 	 * Don't allow the time to be set forward so far it will wrap
@@ -428,37 +427,35 @@ sys_adjtime(struct proc *p, void *v, register_t *retval)
 		syscallarg(const struct timeval *) delta;
 		syscallarg(struct timeval *) olddelta;
 	} */ *uap = v;
-	struct timeval newdelta;
 	const struct timeval *delta = SCARG(uap, delta);
 	struct timeval *olddelta = SCARG(uap, olddelta);
+	struct timeval atv;
 	int error;
 
-	if (olddelta)
-		if ((error = copyout(&adjtimedelta, olddelta,
-		    sizeof(struct timeval))))
+	if (olddelta) {
+		memset(&atv, 0, sizeof(atv));
+		atv.tv_sec = adjtimedelta / 1000000;
+		atv.tv_usec = adjtimedelta % 1000000;
+		if (atv.tv_usec < 0) {
+			atv.tv_usec += 1000000;
+			atv.tv_sec--;
+		}
+
+		if ((error = copyout(&atv, olddelta, sizeof(struct timeval))))
 			return (error);
+	}
 
 	if (delta) {
 		if ((error = suser(p, 0)))
 			return (error);
 
-		if ((error = copyin(delta, &newdelta,
-		    sizeof(struct timeval))))
+		if ((error = copyin(delta, &atv, sizeof(struct timeval))))
 			return (error);
 
-		/* Normalize the correction. */
-		while (newdelta.tv_usec >= 1000000) {
-			newdelta.tv_usec -= 1000000;
-			newdelta.tv_sec += 1;
-		}
-		while (newdelta.tv_usec < 0) {
-			newdelta.tv_usec += 1000000;
-			newdelta.tv_sec -= 1;
-		}
-
-		adjtimedelta.tv_sec  = newdelta.tv_sec;
-		adjtimedelta.tv_usec = newdelta.tv_usec;
+		/* XXX Check for overflow? */
+		adjtimedelta = (int64_t)atv.tv_sec * 1000000 + atv.tv_usec;
 	}
+
 	return (0);
 }
 
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index 2668266c02c..292c4f82b39 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kernel.h,v 1.15 2013/10/06 01:27:49 guenther Exp $	*/
+/*	$OpenBSD: kernel.h,v 1.16 2014/01/30 21:01:59 kettenis Exp $	*/
 /*	$NetBSD: kernel.h,v 1.11 1995/03/03 01:24:16 cgd Exp $	*/
 
 /*-
@@ -61,5 +61,5 @@ extern int lbolt;		/* once a second sleep address */
 extern int tickdelta;
 extern long timedelta;
 
-extern struct timeval adjtimedelta;	/* unapplied time correction */
-extern struct bintime naptime;		/* time spent suspended */
+extern int64_t adjtimedelta;	/* unapplied time correction */
+extern struct bintime naptime;	/* time spent suspended */