1 files changed, 52 insertions, 60 deletions

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index d8c724c..3f5e183 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -266,7 +266,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 /*
  * Divide a ktime value by a nanosecond value
  */
-u64 ktime_divns(const ktime_t kt, s64 div)
+u64 __ktime_divns(const ktime_t kt, s64 div)
 {
 	u64 dclc;
 	int sft = 0;
@@ -282,7 +282,7 @@ u64 ktime_divns(const ktime_t kt, s64 div)
 
 	return dclc;
 }
-EXPORT_SYMBOL_GPL(ktime_divns);
+EXPORT_SYMBOL_GPL(__ktime_divns);
 #endif /* BITS_PER_LONG >= 64 */
 
 /*
@@ -440,6 +440,37 @@ static inline void debug_deactivate(struct hrtimer *timer)
 	trace_hrtimer_cancel(timer);
 }
 
+#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
+static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
+{
+	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	ktime_t expires, expires_next = { .tv64 = KTIME_MAX };
+	int i;
+
+	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+		struct timerqueue_node *next;
+		struct hrtimer *timer;
+
+		next = timerqueue_getnext(&base->active);
+		if (!next)
+			continue;
+
+		timer = container_of(next, struct hrtimer, node);
+		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+		if (expires.tv64 < expires_next.tv64)
+			expires_next = expires;
+	}
+	/*
+	 * clock_was_set() might have changed base->offset of any of
+	 * the clock bases so the result might be negative. Fix it up
+	 * to prevent a false positive in clockevents_program_event().
+	 */
+	if (expires_next.tv64 < 0)
+		expires_next.tv64 = 0;
+	return expires_next;
+}
+#endif
+
 /* High resolution timer related functions */
 #ifdef CONFIG_HIGH_RES_TIMERS
 
@@ -488,32 +519,7 @@ static inline int hrtimer_hres_active(void)
 static void
 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 {
-	int i;
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
-	ktime_t expires, expires_next;
-
-	expires_next.tv64 = KTIME_MAX;
-
-	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
-		struct hrtimer *timer;
-		struct timerqueue_node *next;
-
-		next = timerqueue_getnext(&base->active);
-		if (!next)
-			continue;
-		timer = container_of(next, struct hrtimer, node);
-
-		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
-		/*
-		 * clock_was_set() has changed base->offset so the
-		 * result might be negative. Fix it up to prevent a
-		 * false positive in clockevents_program_event()
-		 */
-		if (expires.tv64 < 0)
-			expires.tv64 = 0;
-		if (expires.tv64 < expires_next.tv64)
-			expires_next = expires;
-	}
+	ktime_t expires_next = __hrtimer_get_next_event(cpu_base);
 
 	if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
 		return;
@@ -587,6 +593,15 @@ static int hrtimer_reprogram(struct hrtimer *timer,
 		return 0;
 
 	/*
+	 * When the target cpu of the timer is currently executing
+	 * hrtimer_interrupt(), then we do not touch the clock event
+	 * device. hrtimer_interrupt() will reevaluate all clock bases
+	 * before reprogramming the device.
+	 */
+	if (cpu_base->in_hrtirq)
+		return 0;
+
+	/*
 	 * If a hang was detected in the last timer interrupt then we
 	 * do not schedule a timer which is earlier than the expiry
 	 * which we enforced in the hang detection. We want the system
@@ -1104,29 +1119,14 @@ EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
 ktime_t hrtimer_get_next_event(void)
 {
 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
-	ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
+	ktime_t mindelta = { .tv64 = KTIME_MAX };
 	unsigned long flags;
-	int i;
 
 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
 
-	if (!hrtimer_hres_active()) {
-		for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
-			struct hrtimer *timer;
-			struct timerqueue_node *next;
-
-			next = timerqueue_getnext(&base->active);
-			if (!next)
-				continue;
-
-			timer = container_of(next, struct hrtimer, node);
-			delta.tv64 = hrtimer_get_expires_tv64(timer);
-			delta = ktime_sub(delta, base->get_time());
-			if (delta.tv64 < mindelta.tv64)
-				mindelta.tv64 = delta.tv64;
-		}
-	}
+	if (!hrtimer_hres_active())
+		mindelta = ktime_sub(__hrtimer_get_next_event(cpu_base),
+				     ktime_get());
 
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
@@ -1253,7 +1253,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
 	raw_spin_lock(&cpu_base->lock);
 	entry_time = now = hrtimer_update_base(cpu_base);
 retry:
-	expires_next.tv64 = KTIME_MAX;
+	cpu_base->in_hrtirq = 1;
 	/*
 	 * We set expires_next to KTIME_MAX here with cpu_base->lock
 	 * held to prevent that a timer is enqueued in our queue via
@@ -1291,28 +1291,20 @@ retry:
 			 * are right-of a not yet expired timer, because that
 			 * timer will have to trigger a wakeup anyway.
 			 */
-
-			if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
-				ktime_t expires;
-
-				expires = ktime_sub(hrtimer_get_expires(timer),
-						    base->offset);
-				if (expires.tv64 < 0)
-					expires.tv64 = KTIME_MAX;
-				if (expires.tv64 < expires_next.tv64)
-					expires_next = expires;
+			if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer))
 				break;
-			}
 
 			__run_hrtimer(timer, &basenow);
 		}
 	}
-
+	/* Reevaluate the clock bases for the next expiry */
+	expires_next = __hrtimer_get_next_event(cpu_base);
 	/*
 	 * Store the new expiry value so the migration code can verify
 	 * against it.
 	 */
 	cpu_base->expires_next = expires_next;
+	cpu_base->in_hrtirq = 0;
 	raw_spin_unlock(&cpu_base->lock);
 
 	/* Reprogramming necessary ? */