Move adjtimedelta from kern_time.c to kern_tc.c.

This will simplify upcoming MP-safety diffs for the timecounting layer.

adjtimedelta is now accessed nowhere outside of kern_tc.c, so we can
remove its extern declaration from kernel.h.  Zeroing adjtimedelta
within timecounter_mtx before we jump the real-time clock is also a
bit safer than what we do now, as we are not racing a simultaneous
tc_windup() call from hardclock(), which itself can modify adjtimedelta
via ntp_update_second().

Discussed with visa@ and mpi@.

ok visa@

2 files changed, 26 insertions, 14 deletions

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index eccf869c19c..565c24b206f 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_tc.c,v 1.38 2019/03/09 23:04:56 cheloha Exp $ */
+/*	$OpenBSD: kern_tc.c,v 1.39 2019/03/10 21:16:15 cheloha Exp $ */
 
 /*
  * Copyright (c) 2000 Poul-Henning Kamp <phk@FreeBSD.org>
@@ -116,6 +116,8 @@ static struct timecounter *timecounters = &dummy_timecounter;
 volatile time_t time_second = 1;
 volatile time_t time_uptime = 0;
 
+int64_t adjtimedelta;		/* unapplied time correction (microseconds) */
+
 struct bintime naptime;
 static int timestepwarnings;
 
@@ -358,6 +360,12 @@ tc_setrealtimeclock(const struct timespec *ts)
 	timespec2bintime(ts, &bt);
 	bintime_sub(&bt, &bt2);
 	bintime_add(&bt2, &timehands->th_boottime);
+
+	/*
+	 * Adjtime in progress is meaningless or harmful after
+	 * setting the clock. Cancel adjtime and then set new time.
+	 */
+	adjtimedelta = 0;
 	timehands->th_boottime = bt;
 
 	/* XXX fiddle all the little crinkly bits around the fiords... */
@@ -724,3 +732,12 @@ tc_adjfreq(int64_t *old, int64_t *new)
 	}
 	return 0;
 }
+
+void
+tc_adjtime(int64_t *old, int64_t *new)
+{
+	if (old != NULL)
+		*old = adjtimedelta;
+	if (new != NULL)
+		adjtimedelta = *new;
+}
diff --git a/sys/kern/kern_time.c b/sys/kern/kern_time.c
index e6b0d817421..5dc32a29b14 100644
--- a/sys/kern/kern_time.c
+++ b/sys/kern/kern_time.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_time.c,v 1.110 2019/01/31 18:23:27 tedu Exp $	*/
+/*	$OpenBSD: kern_time.c,v 1.111 2019/03/10 21:16:15 cheloha Exp $	*/
 /*	$NetBSD: kern_time.c,v 1.20 1996/02/18 11:57:06 fvdl Exp $	*/
 
 /*
@@ -48,9 +48,6 @@
 #include <sys/mount.h>
 #include <sys/syscallargs.h>
 
-
-int64_t adjtimedelta;		/* unapplied time correction (microseconds) */
-
 /* 
  * Time of day and interval timer support.
  *
@@ -96,11 +93,6 @@ settime(const struct timespec *ts)
 		return (EPERM);
 	}
 
-	/*
-	 * Adjtime in progress is meaningless or harmful after
-	 * setting the clock. Cancel adjtime and then set new time.
-	 */
-	adjtimedelta = 0;
 	tc_setrealtimeclock(ts);
 	resettodr();
 
@@ -421,9 +413,10 @@ sys_adjtime(struct proc *p, void *v, register_t *retval)
 		syscallarg(const struct timeval *) delta;
 		syscallarg(struct timeval *) olddelta;
 	} */ *uap = v;
+	struct timeval atv;
 	const struct timeval *delta = SCARG(uap, delta);
 	struct timeval *olddelta = SCARG(uap, olddelta);
-	struct timeval atv;
+	int64_t adjustment, remaining;	
 	int error;
 
 	error = pledge_adjtime(p, delta);
@@ -431,9 +424,10 @@ sys_adjtime(struct proc *p, void *v, register_t *retval)
 		return error;
 
 	if (olddelta) {
+		tc_adjtime(&remaining, NULL);
 		memset(&atv, 0, sizeof(atv));
-		atv.tv_sec = adjtimedelta / 1000000;
-		atv.tv_usec = adjtimedelta % 1000000;
+		atv.tv_sec =  remaining / 1000000;
+		atv.tv_usec = remaining % 1000000;
 		if (atv.tv_usec < 0) {
 			atv.tv_usec += 1000000;
 			atv.tv_sec--;
@@ -454,7 +448,8 @@ sys_adjtime(struct proc *p, void *v, register_t *retval)
 			return (EINVAL);
 
 		/* XXX Check for overflow? */
-		adjtimedelta = (int64_t)atv.tv_sec * 1000000 + atv.tv_usec;
+		adjustment = (int64_t)atv.tv_sec * 1000000 + atv.tv_usec;
+		tc_adjtime(NULL, &adjustment);
 	}
 
 	return (0);