2 files changed, 165 insertions, 4 deletions

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
new file mode 100644
index 000000000000..725892a93b49
--- /dev/null
+++ b/include/trace/events/timer.h
@@ -0,0 +1,137 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM timer
+
+#if !defined(_TRACE_TIMER_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TIMER_H
+
+#include <linux/tracepoint.h>
+#include <linux/timer.h>
+
+/**
+ * timer_init - called when the timer is initialized
+ * @timer:      pointer to struct timer_list
+ */
+TRACE_EVENT(timer_init,
+
+        TP_PROTO(struct timer_list *timer),
+
+        TP_ARGS(timer),
+
+        TP_STRUCT__entry(
+                __field( void *,        timer   )
+        ),
+
+        TP_fast_assign(
+                __entry->timer  = timer;
+        ),
+
+        TP_printk("timer %p", __entry->timer)
+);
+
+/**
+ * timer_start - called when the timer is started
+ * @timer:      pointer to struct timer_list
+ * @expires:    the timers expiry time
+ */
+TRACE_EVENT(timer_start,
+
+        TP_PROTO(struct timer_list *timer, unsigned long expires),
+
+        TP_ARGS(timer, expires),
+
+        TP_STRUCT__entry(
+                __field( void *,        timer           )
+                __field( void *,        function        )
+                __field( unsigned long, expires         )
+                __field( unsigned long, now             )
+        ),
+
+        TP_fast_assign(
+                __entry->timer          = timer;
+                __entry->function       = timer->function;
+                __entry->expires        = expires;
+                __entry->now            = jiffies;
+        ),
+
+        TP_printk("timer %p: func %pf, expires %lu, timeout %ld",
+                  __entry->timer, __entry->function, __entry->expires,
+                  (long)__entry->expires - __entry->now)
+);
+
+/**
+ * timer_expire_entry - called immediately before the timer callback
+ * @timer:      pointer to struct timer_list
+ *
+ * Allows to determine the timer latency.
+ */
+TRACE_EVENT(timer_expire_entry,
+
+        TP_PROTO(struct timer_list *timer),
+
+        TP_ARGS(timer),
+
+        TP_STRUCT__entry(
+                __field( void *,        timer   )
+                __field( unsigned long, now     )
+        ),
+
+        TP_fast_assign(
+                __entry->timer          = timer;
+                __entry->now            = jiffies;
+        ),
+
+        TP_printk("timer %p: now %lu", __entry->timer, __entry->now)
+);
+
+/**
+ * timer_expire_exit - called immediately after the timer callback returns
+ * @timer:      pointer to struct timer_list
+ *
+ * When used in combination with the timer_expire_entry tracepoint we can
+ * determine the runtime of the timer callback function.
+ *
+ * NOTE: Do NOT derefernce timer in TP_fast_assign. The pointer might
+ * be invalid. We solely track the pointer.
+ */
+TRACE_EVENT(timer_expire_exit,
+
+        TP_PROTO(struct timer_list *timer),
+
+        TP_ARGS(timer),
+
+        TP_STRUCT__entry(
+                __field(void *, timer   )
+        ),
+
+        TP_fast_assign(
+                __entry->timer  = timer;
+        ),
+
+        TP_printk("timer %p", __entry->timer)
+);
+
+/**
+ * timer_cancel - called when the timer is canceled
+ * @timer:      pointer to struct timer_list
+ */
+TRACE_EVENT(timer_cancel,
+
+        TP_PROTO(struct timer_list *timer),
+
+        TP_ARGS(timer),
+
+        TP_STRUCT__entry(
+                __field( void *,        timer   )
+        ),
+
+        TP_fast_assign(
+                __entry->timer  = timer;
+        ),
+
+        TP_printk("timer %p", __entry->timer)
+);
+
+#endif /*  _TRACE_TIMER_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/timer.c b/kernel/timer.c
index 8e92be654dad..a7352b00703c 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -46,6 +46,9 @@
 #include <asm/timex.h>
 #include <asm/io.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/timer.h>
+
 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
 
 EXPORT_SYMBOL(jiffies_64);
@@ -521,6 +524,25 @@ static inline void debug_timer_activate(struct timer_list *timer) { }
 static inline void debug_timer_deactivate(struct timer_list *timer) { }
 #endif
 
+static inline void debug_init(struct timer_list *timer)
+{
+        debug_timer_init(timer);
+        trace_timer_init(timer);
+}
+
+static inline void
+debug_activate(struct timer_list *timer, unsigned long expires)
+{
+        debug_timer_activate(timer);
+        trace_timer_start(timer, expires);
+}
+
+static inline void debug_deactivate(struct timer_list *timer)
+{
+        debug_timer_deactivate(timer);
+        trace_timer_cancel(timer);
+}
+
 static void __init_timer(struct timer_list *timer,
                          const char *name,
                          struct lock_class_key *key)
@@ -549,7 +571,7 @@ void init_timer_key(struct timer_list *timer,
                     const char *name,
                     struct lock_class_key *key)
 {
-        debug_timer_init(timer);
+        debug_init(timer);
         __init_timer(timer, name, key);
 }
 EXPORT_SYMBOL(init_timer_key);
@@ -568,7 +590,7 @@ static inline void detach_timer(struct timer_list *timer,
 {
         struct list_head *entry = &timer->entry;
 
-        debug_timer_deactivate(timer);
+        debug_deactivate(timer);
 
         __list_del(entry->prev, entry->next);
         if (clear_pending)
@@ -632,7 +654,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
                         goto out_unlock;
         }
 
-        debug_timer_activate(timer);
+        debug_activate(timer, expires);
 
         new_base = __get_cpu_var(tvec_bases);
 
@@ -787,7 +809,7 @@ void add_timer_on(struct timer_list *timer, int cpu)
         BUG_ON(timer_pending(timer) || !timer->function);
         spin_lock_irqsave(&base->lock, flags);
         timer_set_base(timer, base);
-        debug_timer_activate(timer);
+        debug_activate(timer, timer->expires);
         if (time_before(timer->expires, base->next_timer) &&
             !tbase_get_deferrable(timer->base))
                 base->next_timer = timer->expires;
@@ -1000,7 +1022,9 @@ static inline void __run_timers(struct tvec_base *base)
                                  */
                                 lock_map_acquire(&lockdep_map);
 
+                                trace_timer_expire_entry(timer);
                                 fn(data);
+                                trace_timer_expire_exit(timer);
 
                                 lock_map_release(&lockdep_map);