[PATCH 4/7] time: alarmtimer: Add the tracepoints for alarmtimer

[John Stultz <john.stultz@linaro.org>]

From: Baolin Wang <baolin.wang@linaro.org>

For system debugging, we sometimes want to know who sets one
alarm timer, the time of the timer, when the timer started and
fired and so on. Thus adding tracepoints can help us trace the
alarmtimer information.

For example, when we debug the system supend/resume, if the
system is always resumed by RTC alarm, we can find out which
process set the alarm timer to resume system by below trace log:

......

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:1325376839802714584

......

>From the trace log, we can find out the 'Binder:3292_2' process
set one alarm timer which resumes the system.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
Changes since v4:
 - Initialize 'type' to -1 and rename it in alarmtimer_suspend().
 - Fix typo in subject line.

Changes since v3:
 - Remove the "ALARM_" prefix in the string.
 - Add the ACK by Steven Rostedt.

Changes since v2:
 - Save time as s64 type.
 - Remove 'process_name' parameter and add 'now' parameter.
 - Rename the trace event name.
 - Remove restart trace event.
 - Other optimization.
---
 include/trace/events/alarmtimer.h | 92 +++++++++++++++++++++++++++++++++++++++
 kernel/time/alarmtimer.c          | 16 ++++++-
 2 files changed, 106 insertions(+), 2 deletions(-)
 create mode 100644 include/trace/events/alarmtimer.h

diff --git a/include/trace/events/alarmtimer.h b/include/trace/events/alarmtimer.h
new file mode 100644
index 0000000..61ea556
--- /dev/null
+++ b/include/trace/events/alarmtimer.h
@@ -0,0 +1,92 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM alarmtimer
+
+#if !defined(_TRACE_ALARMTIMER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ALARMTIMER_H
+
+#include <linux/alarmtimer.h>
+#include <linux/rtc.h>
+#include <linux/tracepoint.h>
+
+TRACE_DEFINE_ENUM(ALARM_REALTIME);
+TRACE_DEFINE_ENUM(ALARM_BOOTTIME);
+
+#define show_alarm_type(type)	__print_flags(type, " | ",	\
+	{ 1 << ALARM_REALTIME, "REALTIME" },			\
+	{ 1 << ALARM_BOOTTIME, "BOOTTIME" })
+
+TRACE_EVENT(alarmtimer_suspend,
+
+	TP_PROTO(ktime_t expires, int flag),
+
+	TP_ARGS(expires, flag),
+
+	TP_STRUCT__entry(
+		__field(s64, expires)
+		__field(unsigned char, alarm_type)
+	),
+
+	TP_fast_assign(
+		__entry->expires = expires.tv64;
+		__entry->alarm_type = flag;
+	),
+
+	TP_printk("alarmtimer type:%s expires:%llu",
+		  show_alarm_type((1 << __entry->alarm_type)),
+		  __entry->expires
+	)
+);
+
+DECLARE_EVENT_CLASS(alarm_class,
+
+	TP_PROTO(struct alarm *alarm, ktime_t now),
+
+	TP_ARGS(alarm, now),
+
+	TP_STRUCT__entry(
+		__field(void *,	alarm)
+		__field(unsigned char, alarm_type)
+		__field(s64, expires)
+		__field(s64, now)
+	),
+
+	TP_fast_assign(
+		__entry->alarm = alarm;
+		__entry->alarm_type = alarm->type;
+		__entry->expires = alarm->node.expires.tv64;
+		__entry->now = now.tv64;
+	),
+
+	TP_printk("alarmtimer:%p type:%s expires:%llu now:%llu",
+		  __entry->alarm,
+		  show_alarm_type((1 << __entry->alarm_type)),
+		  __entry->expires,
+		  __entry->now
+	)
+);
+
+DEFINE_EVENT(alarm_class, alarmtimer_fired,
+
+	TP_PROTO(struct alarm *alarm, ktime_t now),
+
+	TP_ARGS(alarm, now)
+);
+
+DEFINE_EVENT(alarm_class, alarmtimer_start,
+
+	TP_PROTO(struct alarm *alarm, ktime_t now),
+
+	TP_ARGS(alarm, now)
+);
+
+DEFINE_EVENT(alarm_class, alarmtimer_cancel,
+
+	TP_PROTO(struct alarm *alarm, ktime_t now),
+
+	TP_ARGS(alarm, now)
+);
+
+#endif /* _TRACE_ALARMTIMER_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 12dd190..4590f23 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
@@ -194,6 +197,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
 	}
 	spin_unlock_irqrestore(&base->lock, flags);
 
+	trace_alarmtimer_fired(alarm, base->gettime());
 	return ret;
 
 }
@@ -222,7 +226,7 @@ static int alarmtimer_suspend(struct device *dev)
 	ktime_t min, now;
 	unsigned long flags;
 	struct rtc_device *rtc;
-	int i;
+	int i, min_type = -1;
 	int ret;
 
 	spin_lock_irqsave(&freezer_delta_lock, flags);
@@ -247,8 +251,10 @@ 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)) {
 			min = delta;
+			min_type = i;
+		}
 	}
 	if (min.tv64 == 0)
 		return 0;
@@ -264,6 +270,8 @@ static int alarmtimer_suspend(struct device *dev)
 	now = rtc_tm_to_ktime(tm);
 	now = ktime_add(now, min);
 
+	trace_alarmtimer_suspend(now, min_type);
+
 	/* Set alarm, if in the past reject suspend briefly to handle */
 	ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
 	if (ret < 0)
@@ -342,6 +350,8 @@ 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 +400,8 @@ 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);
-- 
2.7.4