[PATCH 3/6] trace: Add tracepoints to IRQ work run handler

[Vaibhav Nagarnaik <vnagarnaik@google.com>]

This is a part of overall effort to trace all the interrupts happening
in a system to figure out what time is spent in kernel space versus user
space.

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
---
 include/trace/events/irq.h |   44 ++++++++++++++++++++++++++++++++++++++++++++
 kernel/irq_work.c          |    4 ++++
 2 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index e6e72e0..d8fab89 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -295,6 +295,50 @@ DEFINE_EVENT(timer_interrupt, timer_nohz_exit,
 	TP_ARGS(ignore)
 );
 
+DECLARE_EVENT_CLASS(irq_work,
+
+	TP_PROTO(unsigned int ignore),
+
+	TP_ARGS(ignore),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	ignore	)
+	),
+
+	TP_fast_assign(
+		__entry->ignore = ignore;
+	),
+
+	TP_printk("%u", __entry->ignore)
+);
+
+/**
+ * irq_work_run_entry - called immediately after entering the irq work
+ * handler
+ *
+ * When used in combination with the irq_work_run_exit tracepoint
+ * we can determine the irq work handler runtime.
+ */
+DEFINE_EVENT(irq_work, irq_work_run_entry,
+
+	TP_PROTO(unsigned int ignore),
+
+	TP_ARGS(ignore)
+);
+
+/**
+ * irq_work_run_exit - called just before the irq work handler returns
+ *
+ * When used in combination with the irq_work_run_entry tracepoint
+ * we can determine the irq work handler runtime.
+ */
+DEFINE_EVENT(irq_work, irq_work_run_exit,
+
+	TP_PROTO(unsigned int ignore),
+
+	TP_ARGS(ignore)
+);
+
 #endif /*  _TRACE_IRQ_H */
 
 /* This part must be outside protection */
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index c58fa7d..7e78122 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/irq_work.h>
 #include <linux/hardirq.h>
+#include <trace/events/irq.h>
 
 /*
  * An entry can be in one of four states:
@@ -125,6 +126,8 @@ void irq_work_run(void)
 	if (this_cpu_read(irq_work_list) == NULL)
 		return;
 
+	trace_irq_work_run_entry(0);
+
 	BUG_ON(!in_irq());
 	BUG_ON(!irqs_disabled());
 
@@ -149,6 +152,7 @@ void irq_work_run(void)
 			      next_flags(NULL, IRQ_WORK_BUSY),
 			      NULL);
 	}
+	trace_irq_work_run_exit(0);
 }
 EXPORT_SYMBOL_GPL(irq_work_run);
 
-- 
1.7.3.1