2 files changed, 52 insertions, 58 deletions

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index a036d058a249..05f6df1fdf5b 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -170,6 +170,7 @@ enum  hrtimer_base_type {
  * @clock_was_set:      Indicates that clock was set from irq context.
  * @expires_next:       absolute time of the next event which was scheduled
  *                      via clock_set_next_event()
+ * @in_hrtirq:          hrtimer_interrupt() is currently executing
  * @hres_active:        State of high resolution mode
  * @hang_detected:      The last hrtimer interrupt detected a hang
  * @nr_events:          Total number of hrtimer interrupt events
@@ -185,6 +186,7 @@ struct hrtimer_cpu_base {
         unsigned int                    clock_was_set;
 #ifdef CONFIG_HIGH_RES_TIMERS
         ktime_t                         expires_next;
+        int                             in_hrtirq;
         int                             hres_active;
         int                             hang_detected;
         unsigned long                   nr_events;
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 37e50aadd471..b663653a5d5b 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -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)
+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 ? */