Index: sys/kern/kern_clocksource.c
===================================================================
--- sys/kern/kern_clocksource.c
+++ sys/kern/kern_clocksource.c
@@ -65,7 +65,8 @@
 static void		configtimer(int start);
 static int		round_freq(struct eventtimer *et, int freq);
 
-static sbintime_t	getnextcpuevent(int idle);
+struct pcpu_state;
+static sbintime_t	getnextcpuevent(struct pcpu_state *state, int idle);
 static sbintime_t	getnextevent(void);
 static int		handleevents(sbintime_t now, int fake);
 
@@ -212,9 +213,8 @@
 		state->nextcall = state->nextcallopt = SBT_MAX;
 		callout_process(now);
 	}
-
-	t = getnextcpuevent(0);
 	ET_HW_LOCK(state);
+	t = getnextcpuevent(state, 0);
 	if (!busy) {
 		state->idle = 0;
 		state->nextevent = t;
@@ -229,13 +229,11 @@
  * Schedule binuptime of the next event on current CPU.
  */
 static sbintime_t
-getnextcpuevent(int idle)
+getnextcpuevent(struct pcpu_state *state, int idle)
 {
 	sbintime_t event;
-	struct pcpu_state *state;
 	u_int hardfreq;
 
-	state = DPCPU_PTR(timerstate);
 	/* Handle hardclock() events, skipping some if CPU is idle. */
 	event = state->nexthard;
 	if (idle) {
@@ -686,8 +684,8 @@
 	struct thread *td;
 
 	state = DPCPU_PTR(timerstate);
-	now = sbinuptime();
 	ET_HW_LOCK(state);
+	now = sbinuptime();
 	state->now = now;
 	hardclock_sync(curcpu);
 	spinlock_enter();
@@ -772,14 +770,14 @@
 	    )
 		return (-1);
 	state = DPCPU_PTR(timerstate);
+	ET_HW_LOCK(state);
 	if (periodic)
 		now = state->now;
 	else
 		now = sbinuptime();
 	CTR3(KTR_SPARE2, "idle at %d:    now  %d.%08x",
 	    curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
-	t = getnextcpuevent(1);
-	ET_HW_LOCK(state);
+	t = getnextcpuevent(state, 1);
 	state->idle = 1;
 	state->nextevent = t;
 	if (!periodic)
@@ -799,15 +797,15 @@
 	struct thread *td;
 
 	state = DPCPU_PTR(timerstate);
-	if (state->idle == 0 || busy)
+	if (atomic_load_int(&state->idle) == 0 || busy)
 		return;
+	spinlock_enter();
 	if (periodic)
 		now = state->now;
 	else
 		now = sbinuptime();
 	CTR3(KTR_SPARE2, "active at %d:  now  %d.%08x",
 	    curcpu, (int)(now >> 32), (u_int)(now & 0xffffffff));
-	spinlock_enter();
 	td = curthread;
 	td->td_intr_nesting_level++;
 	handleevents(now, 1);