2 files changed, 47 insertions, 8 deletions

diff --git a/include/linux/alarmtimer.h b/include/linux/alarmtimer.h
index c854a8efa863..304124a6c982 100644
--- a/include/linux/alarmtimer.h
+++ b/include/linux/alarmtimer.h
@@ -18,6 +18,11 @@ enum alarmtimer_restart {
         ALARMTIMER_RESTART,
 };
 
+
+#define ALARMTIMER_STATE_INACTIVE       0x00
+#define ALARMTIMER_STATE_ENQUEUED       0x01
+#define ALARMTIMER_STATE_CALLBACK       0x02
+
 /**
  * struct alarm - Alarm timer structure
  * @node:       timerqueue node for adding to the event list this value
@@ -32,7 +37,7 @@ struct alarm {
         struct timerqueue_node  node;
         enum alarmtimer_restart (*function)(struct alarm *, ktime_t now);
         enum alarmtimer_type    type;
-        bool                    enabled;
+        int                     state;
         void                    *data;
 };
 
@@ -43,4 +48,31 @@ void alarm_cancel(struct alarm *alarm);
 
 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);
 
+/*
+ * A alarmtimer is active, when it is enqueued into timerqueue or the
+ * callback function is running.
+ */
+static inline int alarmtimer_active(const struct alarm *timer)
+{
+        return timer->state != ALARMTIMER_STATE_INACTIVE;
+}
+
+/*
+ * Helper function to check, whether the timer is on one of the queues
+ */
+static inline int alarmtimer_is_queued(struct alarm *timer)
+{
+        return timer->state & ALARMTIMER_STATE_ENQUEUED;
+}
+
+/*
+ * Helper function to check, whether the timer is running the callback
+ * function
+ */
+static inline int alarmtimer_callback_running(struct alarm *timer)
+{
+        return timer->state & ALARMTIMER_STATE_CALLBACK;
+}
+
+
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 90935591dd44..5b14cc29b6a6 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -126,6 +126,8 @@ static struct rtc_device *alarmtimer_get_rtcdev(void)
 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
 {
         timerqueue_add(&base->timerqueue, &alarm->node);
+        alarm->state |= ALARMTIMER_STATE_ENQUEUED;
+
         if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
                 hrtimer_try_to_cancel(&base->timer);
                 hrtimer_start(&base->timer, alarm->node.expires,
@@ -147,7 +149,12 @@ static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
 {
         struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
 
+        if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
+                return;
+
         timerqueue_del(&base->timerqueue, &alarm->node);
+        alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
+
         if (next == &alarm->node) {
                 hrtimer_try_to_cancel(&base->timer);
                 next = timerqueue_getnext(&base->timerqueue);
@@ -188,16 +195,18 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
                 alarm = container_of(next, struct alarm, node);
 
                 timerqueue_del(&base->timerqueue, &alarm->node);
-                alarm->enabled = 0;
+                alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
 
+                alarm->state |= ALARMTIMER_STATE_CALLBACK;
                 spin_unlock_irqrestore(&base->lock, flags);
                 if (alarm->function)
                         restart = alarm->function(alarm, now);
                 spin_lock_irqsave(&base->lock, flags);
+                alarm->state &= ~ALARMTIMER_STATE_CALLBACK;
 
                 if (restart != ALARMTIMER_NORESTART) {
                         timerqueue_add(&base->timerqueue, &alarm->node);
-                        alarm->enabled = 1;
+                        alarm->state |= ALARMTIMER_STATE_ENQUEUED;
                 }
         }
 
@@ -305,7 +314,7 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
         timerqueue_init(&alarm->node);
         alarm->function = function;
         alarm->type = type;
-        alarm->enabled = 0;
+        alarm->state = ALARMTIMER_STATE_INACTIVE;
 }
 
 /**
@@ -319,11 +328,10 @@ void alarm_start(struct alarm *alarm, ktime_t start)
         unsigned long flags;
 
         spin_lock_irqsave(&base->lock, flags);
-        if (alarm->enabled)
+        if (alarmtimer_active(alarm))
                 alarmtimer_remove(base, alarm);
         alarm->node.expires = start;
         alarmtimer_enqueue(base, alarm);
-        alarm->enabled = 1;
         spin_unlock_irqrestore(&base->lock, flags);
 }
 
@@ -337,9 +345,8 @@ void alarm_cancel(struct alarm *alarm)
         unsigned long flags;
 
         spin_lock_irqsave(&base->lock, flags);
-        if (alarm->enabled)
+        if (alarmtimer_is_queued(alarm))
                 alarmtimer_remove(base, alarm);
-        alarm->enabled = 0;
         spin_unlock_irqrestore(&base->lock, flags);
 }