1 files changed, 181 insertions, 85 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index ea5e1a928d5b..c436e790b21b 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -53,27 +53,6 @@ static struct rtc_device	*rtcdev;
 static DEFINE_SPINLOCK(rtcdev_lock);
 
 /**
- * has_wakealarm - check rtc device has wakealarm ability
- * @dev: current device
- * @name_ptr: name to be returned
- *
- * This helper function checks to see if the rtc device can wake
- * from suspend.
- */
-static int has_wakealarm(struct device *dev, void *name_ptr)
-{
-        struct rtc_device *candidate = to_rtc_device(dev);
-
-        if (!candidate->ops->set_alarm)
-                return 0;
-        if (!device_may_wakeup(candidate->dev.parent))
-                return 0;
-
-        *(const char **)name_ptr = dev_name(dev);
-        return 1;
-}
-
-/**
  * alarmtimer_get_rtcdev - Return selected rtcdevice
  *
  * This function returns the rtc device to use for wakealarms.
@@ -82,37 +61,64 @@ static int has_wakealarm(struct device *dev, void *name_ptr)
  */
 static struct rtc_device *alarmtimer_get_rtcdev(void)
 {
-        struct device *dev;
-        char *str;
         unsigned long flags;
         struct rtc_device *ret;
 
         spin_lock_irqsave(&rtcdev_lock, flags);
-        if (!rtcdev) {
-                /* Find an rtc device and init the rtc_timer */
-                dev = class_find_device(rtc_class, NULL, &str, has_wakealarm);
-                /* If we have a device then str is valid. See has_wakealarm() */
-                if (dev) {
-                        rtcdev = rtc_class_open(str);
-                        /*
-                         * Drop the reference we got in class_find_device,
-                         * rtc_open takes its own.
-                         */
-                        put_device(dev);
-                        rtc_timer_init(&rtctimer, NULL, NULL);
-                }
-        }
         ret = rtcdev;
         spin_unlock_irqrestore(&rtcdev_lock, flags);
 
         return ret;
 }
+
+
+static int alarmtimer_rtc_add_device(struct device *dev,
+                                struct class_interface *class_intf)
+{
+        unsigned long flags;
+        struct rtc_device *rtc = to_rtc_device(dev);
+
+        if (rtcdev)
+                return -EBUSY;
+
+        if (!rtc->ops->set_alarm)
+                return -1;
+        if (!device_may_wakeup(rtc->dev.parent))
+                return -1;
+
+        spin_lock_irqsave(&rtcdev_lock, flags);
+        if (!rtcdev) {
+                rtcdev = rtc;
+                /* hold a reference so it doesn't go away */
+                get_device(dev);
+        }
+        spin_unlock_irqrestore(&rtcdev_lock, flags);
+        return 0;
+}
+
+static struct class_interface alarmtimer_rtc_interface = {
+        .add_dev = &alarmtimer_rtc_add_device,
+};
+
+static int alarmtimer_rtc_interface_setup(void)
+{
+        alarmtimer_rtc_interface.class = rtc_class;
+        return class_interface_register(&alarmtimer_rtc_interface);
+}
+static void alarmtimer_rtc_interface_remove(void)
+{
+        class_interface_unregister(&alarmtimer_rtc_interface);
+}
 #else
-#define alarmtimer_get_rtcdev() (0)
-#define rtcdev (0)
+static inline struct rtc_device *alarmtimer_get_rtcdev(void)
+{
+        return NULL;
+}
+#define rtcdev (NULL)
+static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
+static inline void alarmtimer_rtc_interface_remove(void) { }
 #endif
 
-
 /**
  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
  * @base: pointer to the base where the timer is being run
@@ -126,6 +132,8 @@ 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 +155,12 @@ 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);
@@ -174,6 +187,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
         unsigned long flags;
         ktime_t now;
         int ret = HRTIMER_NORESTART;
+        int restart = ALARMTIMER_NORESTART;
 
         spin_lock_irqsave(&base->lock, flags);
         now = base->gettime();
@@ -187,17 +201,19 @@ 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;
-                /* Re-add periodic timers */
-                if (alarm->period.tv64) {
-                        alarm->node.expires = ktime_add(expired, alarm->period);
-                        timerqueue_add(&base->timerqueue, &alarm->node);
-                        alarm->enabled = 1;
-                }
+                alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
+
+                alarm->state |= ALARMTIMER_STATE_CALLBACK;
                 spin_unlock_irqrestore(&base->lock, flags);
                 if (alarm->function)
-                        alarm->function(alarm);
+                        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->state |= ALARMTIMER_STATE_ENQUEUED;
+                }
         }
 
         if (next) {
@@ -234,7 +250,7 @@ static int alarmtimer_suspend(struct device *dev)
         freezer_delta = ktime_set(0, 0);
         spin_unlock_irqrestore(&freezer_delta_lock, flags);
 
-        rtc = rtcdev;
+        rtc = alarmtimer_get_rtcdev();
         /* If we have no rtcdev, just return */
         if (!rtc)
                 return 0;
@@ -299,53 +315,111 @@ static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
  * @function: callback that is run when the alarm fires
  */
 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
-                void (*function)(struct alarm *))
+                enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
 {
         timerqueue_init(&alarm->node);
-        alarm->period = ktime_set(0, 0);
         alarm->function = function;
         alarm->type = type;
-        alarm->enabled = 0;
+        alarm->state = ALARMTIMER_STATE_INACTIVE;
 }
 
 /**
  * alarm_start - Sets an alarm to fire
  * @alarm: ptr to alarm to set
  * @start: time to run the alarm
- * @period: period at which the alarm will recur
  */
-void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period)
+void alarm_start(struct alarm *alarm, ktime_t start)
 {
         struct alarm_base *base = &alarm_bases[alarm->type];
         unsigned long flags;
 
         spin_lock_irqsave(&base->lock, flags);
-        if (alarm->enabled)
+        if (alarmtimer_active(alarm))
                 alarmtimer_remove(base, alarm);
         alarm->node.expires = start;
-        alarm->period = period;
         alarmtimer_enqueue(base, alarm);
-        alarm->enabled = 1;
         spin_unlock_irqrestore(&base->lock, flags);
 }
 
 /**
- * alarm_cancel - Tries to cancel an alarm timer
+ * alarm_try_to_cancel - Tries to cancel an alarm timer
  * @alarm: ptr to alarm to be canceled
+ *
+ * Returns 1 if the timer was canceled, 0 if it was not running,
+ * and -1 if the callback was running
  */
-void alarm_cancel(struct alarm *alarm)
+int alarm_try_to_cancel(struct alarm *alarm)
 {
         struct alarm_base *base = &alarm_bases[alarm->type];
         unsigned long flags;
-
+        int ret = -1;
         spin_lock_irqsave(&base->lock, flags);
-        if (alarm->enabled)
+
+        if (alarmtimer_callback_running(alarm))
+                goto out;
+
+        if (alarmtimer_is_queued(alarm)) {
                 alarmtimer_remove(base, alarm);
-        alarm->enabled = 0;
+                ret = 1;
+        } else
+                ret = 0;
+out:
         spin_unlock_irqrestore(&base->lock, flags);
+        return ret;
+}
+
+
+/**
+ * alarm_cancel - Spins trying to cancel an alarm timer until it is done
+ * @alarm: ptr to alarm to be canceled
+ *
+ * Returns 1 if the timer was canceled, 0 if it was not active.
+ */
+int alarm_cancel(struct alarm *alarm)
+{
+        for (;;) {
+                int ret = alarm_try_to_cancel(alarm);
+                if (ret >= 0)
+                        return ret;
+                cpu_relax();
+        }
+}
+
+
+u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
+{
+        u64 overrun = 1;
+        ktime_t delta;
+
+        delta = ktime_sub(now, alarm->node.expires);
+
+        if (delta.tv64 < 0)
+                return 0;
+
+        if (unlikely(delta.tv64 >= interval.tv64)) {
+                s64 incr = ktime_to_ns(interval);
+
+                overrun = ktime_divns(delta, incr);
+
+                alarm->node.expires = ktime_add_ns(alarm->node.expires,
+                                                        incr*overrun);
+
+                if (alarm->node.expires.tv64 > now.tv64)
+                        return overrun;
+                /*
+                 * This (and the ktime_add() below) is the
+                 * correction for exact:
+                 */
+                overrun++;
+        }
+
+        alarm->node.expires = ktime_add(alarm->node.expires, interval);
+        return overrun;
 }
 
 
+
+
 /**
  * clock2alarm - helper that converts from clockid to alarmtypes
  * @clockid: clockid.
@@ -365,12 +439,21 @@ static enum alarmtimer_type clock2alarm(clockid_t clockid)
  *
  * Posix timer callback for expired alarm timers.
  */
-static void alarm_handle_timer(struct alarm *alarm)
+static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
+                                                        ktime_t now)
 {
         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
-                                                it.alarmtimer);
+                                                it.alarm.alarmtimer);
         if (posix_timer_event(ptr, 0) != 0)
                 ptr->it_overrun++;
+
+        /* Re-add periodic timers */
+        if (ptr->it.alarm.interval.tv64) {
+                ptr->it_overrun += alarm_forward(alarm, now,
+                                                ptr->it.alarm.interval);
+                return ALARMTIMER_RESTART;
+        }
+        return ALARMTIMER_NORESTART;
 }
 
 /**
@@ -427,7 +510,7 @@ static int alarm_timer_create(struct k_itimer *new_timer)
 
         type = clock2alarm(new_timer->it_clock);
         base = &alarm_bases[type];
-        alarm_init(&new_timer->it.alarmtimer, type, alarm_handle_timer);
+        alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
         return 0;
 }
 
@@ -444,9 +527,9 @@ static void alarm_timer_get(struct k_itimer *timr,
         memset(cur_setting, 0, sizeof(struct itimerspec));
 
         cur_setting->it_interval =
-                        ktime_to_timespec(timr->it.alarmtimer.period);
+                        ktime_to_timespec(timr->it.alarm.interval);
         cur_setting->it_value =
-                        ktime_to_timespec(timr->it.alarmtimer.node.expires);
+                ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
         return;
 }
 
@@ -461,7 +544,9 @@ static int alarm_timer_del(struct k_itimer *timr)
         if (!rtcdev)
                 return -ENOTSUPP;
 
-        alarm_cancel(&timr->it.alarmtimer);
+        if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
+                return TIMER_RETRY;
+
         return 0;
 }
 
@@ -481,25 +566,17 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
         if (!rtcdev)
                 return -ENOTSUPP;
 
-        /*
-         * XXX HACK! Currently we can DOS a system if the interval
-         * period on alarmtimers is too small. Cap the interval here
-         * to 100us and solve this properly in a future patch! -jstultz
-         */
-        if ((new_setting->it_interval.tv_sec == 0) &&
-                        (new_setting->it_interval.tv_nsec < 100000))
-                new_setting->it_interval.tv_nsec = 100000;
-
         if (old_setting)
                 alarm_timer_get(timr, old_setting);
 
         /* If the timer was already set, cancel it */
-        alarm_cancel(&timr->it.alarmtimer);
+        if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
+                return TIMER_RETRY;
 
         /* start the timer */
-        alarm_start(&timr->it.alarmtimer,
-                        timespec_to_ktime(new_setting->it_value),
-                        timespec_to_ktime(new_setting->it_interval));
+        timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
+        alarm_start(&timr->it.alarm.alarmtimer,
+                        timespec_to_ktime(new_setting->it_value));
         return 0;
 }
 
@@ -509,13 +586,15 @@ static int alarm_timer_set(struct k_itimer *timr, int flags,
  *
  * Wakes up the task that set the alarmtimer
  */
-static void alarmtimer_nsleep_wakeup(struct alarm *alarm)
+static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
+                                                                ktime_t now)
 {
         struct task_struct *task = (struct task_struct *)alarm->data;
 
         alarm->data = NULL;
         if (task)
                 wake_up_process(task);
+        return ALARMTIMER_NORESTART;
 }
 
 /**
@@ -530,7 +609,7 @@ static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
         alarm->data = (void *)current;
         do {
                 set_current_state(TASK_INTERRUPTIBLE);
-                alarm_start(alarm, absexp, ktime_set(0, 0));
+                alarm_start(alarm, absexp);
                 if (likely(alarm->data))
                         schedule();
 
@@ -691,6 +770,7 @@ static struct platform_driver alarmtimer_driver = {
  */
 static int __init alarmtimer_init(void)
 {
+        struct platform_device *pdev;
         int error = 0;
         int i;
         struct k_clock alarm_clock = {
@@ -719,10 +799,26 @@ static int __init alarmtimer_init(void)
                                 HRTIMER_MODE_ABS);
                 alarm_bases[i].timer.function = alarmtimer_fired;
         }
+
+        error = alarmtimer_rtc_interface_setup();
+        if (error)
+                return error;
+
         error = platform_driver_register(&alarmtimer_driver);
-        platform_device_register_simple("alarmtimer", -1, NULL, 0);
+        if (error)
+                goto out_if;
 
+        pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
+        if (IS_ERR(pdev)) {
+                error = PTR_ERR(pdev);
+                goto out_drv;
+        }
+        return 0;
+
+out_drv:
+        platform_driver_unregister(&alarmtimer_driver);
+out_if:
+        alarmtimer_rtc_interface_remove();
         return error;
 }
 device_initcall(alarmtimer_init);
-