Particlly MFcalloutng r238425 (by davide):

Fix an issue related to old periodic timers. The code in kern_clocksource.c
uses interrupt to keep track of time, and this time may not match with
binuptime(). In order to address such incoherency, switch periodic timers
to binuptime().

Except further calloutng it is needed for already present cyclic subsystem.

1 files changed, 6 insertions, 11 deletions

diff --git a/sys/kern/kern_clocksource.c b/sys/kern/kern_clocksource.c
index a622c32..a73536f 100644
--- a/sys/kern/kern_clocksource.c
+++ b/sys/kern/kern_clocksource.c
@@ -356,13 +356,12 @@ timercb(struct eventtimer *et, void *arg)
 		next = &state->nexttick;
 	} else
 		next = &nexttick;
-	if (periodic) {
-		now = *next;	/* Ex-next tick time becomes present time. */
+	binuptime(&now); 
+	if (periodic) { 
+		*next = now;
 		bintime_addx(next, timerperiod.frac); /* Next tick in 1 period. */
-	} else {
-		binuptime(&now);	/* Get present time from hardware. */
-		next->sec = -1;		/* Next tick is not scheduled yet. */
-	}
+	} else
+		next->sec = -1;	/* Next tick is not scheduled yet. */
 	state->now = now;
 	CTR4(KTR_SPARE2, "intr at %d:    now  %d.%08x%08x",
 	    curcpu, (int)(now.sec), (u_int)(now.frac >> 32),
@@ -714,11 +713,7 @@ cpu_initclocks_ap(void)
 	state = DPCPU_PTR(timerstate);
 	binuptime(&now);
 	ET_HW_LOCK(state);
-	if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 && periodic) {
-		state->now = nexttick;
-		bintime_sub(&state->now, &timerperiod);
-	} else
-		state->now = now;
+	state->now = now;
 	hardclock_sync(curcpu);
 	handleevents(&state->now, 2);
 	if (timer->et_flags & ET_FLAGS_PERCPU)