alarmtimer: Add tracepoints for alarm timers

Alarm timers are one of the mechanisms to wake up a system from suspend,
but there exist no tracepoints to analyse which process/thread armed an
alarmtimer.

Add tracepoints for start/cancel/expire of individual alarm timers and one
for tracing the suspend time decision when to resume the system.

The following trace excerpt illustrates the new mechanism:

Binder:3292_2-3304  [000] d..2   149.981123: alarmtimer_cancel:
alarmtimer:ffffffc1319a7800 type:REALTIME
expires:1325463120000000000 now:1325376810370370245

Binder:3292_2-3304  [000] d..2   149.981136: alarmtimer_start:
alarmtimer:ffffffc1319a7800 type:REALTIME
expires:1325376840000000000 now:1325376810370384591

Binder:3292_9-3953  [000] d..2   150.212991: alarmtimer_cancel:
alarmtimer:ffffffc1319a5a00 type:BOOTTIME
expires:179552000000 now:150154008122

Binder:3292_9-3953  [000] d..2   150.213006: alarmtimer_start:
alarmtimer:ffffffc1319a5a00 type:BOOTTIME
expires:179551000000 now:150154025622

system_server-3000  [002] ...1  162.701940: alarmtimer_suspend:
alarmtimer type:REALTIME expires:1325376840000000000

The wakeup time which is selected at suspend time allows to map it back to
the task arming the timer: Binder:3292_2.

[ tglx: Store alarm timer expiry time instead of some useless RTC relative
  	information, add proper type information for wakeups which are
  	handled via the clock_nanosleep/freezer and massage the changelog. ]

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1480372524-15181-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 43 insertions, 10 deletions

diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index a15caa3d1721..9b08ca391aed 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -26,6 +26,9 @@
 #include <linux/workqueue.h>
 #include <linux/freezer.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/alarmtimer.h>
+
 /**
  * struct alarm_base - Alarm timer bases
  * @lock:		Lock for syncrhonized access to the base
@@ -40,7 +43,9 @@ static struct alarm_base {
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
-/* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
+/* freezer information to handle clock_nanosleep triggered wakeups */
+static enum alarmtimer_type freezer_alarmtype;
+static ktime_t freezer_expires;
 static ktime_t freezer_delta;
 static DEFINE_SPINLOCK(freezer_delta_lock);
 
@@ -194,6 +199,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	}
 	spin_unlock_irqrestore(&base->lock, flags);
 
+	trace_alarmtimer_fired(alarm, base->gettime());
 	return ret;
 
 }
@@ -218,15 +224,16 @@ EXPORT_SYMBOL_GPL(alarm_expires_remaining);
  */
 static int alarmtimer_suspend(struct device *dev)
 {
-	struct rtc_time tm;
-	ktime_t min, now;
-	unsigned long flags;
+	ktime_t min, now, expires;
+	int i, ret, type;
 	struct rtc_device *rtc;
-	int i;
-	int ret;
+	unsigned long flags;
+	struct rtc_time tm;
 
 	spin_lock_irqsave(&freezer_delta_lock, flags);
 	min = freezer_delta;
+	expires = freezer_expires;
+	type = freezer_alarmtype;
 	freezer_delta = ktime_set(0, 0);
 	spin_unlock_irqrestore(&freezer_delta_lock, flags);
 
@@ -247,8 +254,11 @@ static int alarmtimer_suspend(struct device *dev)
 		if (!next)
 			continue;
 		delta = ktime_sub(next->expires, base->gettime());
-		if (!min.tv64 || (delta.tv64 < min.tv64))
+		if (!min.tv64 || (delta.tv64 < min.tv64)) {
+			expires = next->expires;
 			min = delta;
+			type = i;
+		}
 	}
 	if (min.tv64 == 0)
 		return 0;
@@ -258,6 +268,8 @@ static int alarmtimer_suspend(struct device *dev)
 		return -EBUSY;
 	}
 
+	trace_alarmtimer_suspend(expires, type);
+
 	/* Setup an rtc timer to fire that far in the future */
 	rtc_timer_cancel(rtc, &rtctimer);
 	rtc_read_time(rtc, &tm);
@@ -295,15 +307,32 @@ static int alarmtimer_resume(struct device *dev)
 
 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
 {
-	ktime_t delta;
+	struct alarm_base *base;
 	unsigned long flags;
-	struct alarm_base *base = &alarm_bases[type];
+	ktime_t delta;
+
+	switch(type) {
+	case ALARM_REALTIME:
+		base = &alarm_bases[ALARM_REALTIME];
+		type = ALARM_REALTIME_FREEZER;
+		break;
+	case ALARM_BOOTTIME:
+		base = &alarm_bases[ALARM_BOOTTIME];
+		type = ALARM_BOOTTIME_FREEZER;
+		break;
+	default:
+		WARN_ONCE(1, "Invalid alarm type: %d\n", type);
+		return;
+	}
 
 	delta = ktime_sub(absexp, base->gettime());
 
 	spin_lock_irqsave(&freezer_delta_lock, flags);
-	if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
+	if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64)) {
 		freezer_delta = delta;
+		freezer_expires = absexp;
+		freezer_alarmtype = type;
+	}
 	spin_unlock_irqrestore(&freezer_delta_lock, flags);
 }
 
@@ -342,6 +371,8 @@ void alarm_start(struct alarm *alarm, ktime_t start)
 	alarmtimer_enqueue(base, alarm);
 	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
 	spin_unlock_irqrestore(&base->lock, flags);
+
+	trace_alarmtimer_start(alarm, base->gettime());
 }
 EXPORT_SYMBOL_GPL(alarm_start);
 
@@ -390,6 +421,8 @@ int alarm_try_to_cancel(struct alarm *alarm)
 	if (ret >= 0)
 		alarmtimer_dequeue(base, alarm);
 	spin_unlock_irqrestore(&base->lock, flags);
+
+	trace_alarmtimer_cancel(alarm, base->gettime());
 	return ret;
 }
 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);