[PATCH v4] ftrace: add a tracepoint for __raise_softirq_irqoff()

[Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>]

From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

This patch is modified from Mathieu Desnoyers' patch. The original patch
can be found here: 
	http://marc.info/?l=linux-kernel&m=123791201816245&w=2
This tracepoint can trace the time stamp when softirq action is raised. 

Changelog for v1 -> v2: 
1: Use TRACE_EVENT instead of DEFINE_TRACE
2: Move the tracepoint from raise_softirq_irqoff() to
   __raise_softirq_irqoff()

Changelog for v2 -> v3: 
Move the definition of __raise_softifq_irqoff() to .c file when
CONFIG_TRACEPOINTS is enabled, to avoid recursive includes

Changelog for v3 -> v4: 
1: Come back to v2, and use forward declarations to avoid
   recursive includes as Mathieu's suggestion
2: Modifiy the tracepoint name
3: Add comments for this tracepoint

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Review-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
 include/linux/interrupt.h  |    9 ++++++++-
 include/trace/events/irq.h |   27 ++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index dd574d5..51e7909 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -18,6 +18,7 @@
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/system.h>
+#include <trace/events/irq.h>
 
 /*
  * These correspond to the IORESOURCE_IRQ_* defines in
@@ -361,7 +362,13 @@ asmlinkage void do_softirq(void);
 asmlinkage void __do_softirq(void);
 extern void open_softirq(int nr, void (*action)(struct softirq_action *));
 extern void softirq_init(void);
-#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
+
+static inline void __raise_softirq_irqoff(unsigned int nr)
+{
+	trace_softirq_raise(nr);
+	or_softirq_pending(1UL << nr);
+}
+
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
 extern void wakeup_softirqd(void);
diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index 32a9f7e..08fa63b 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -2,11 +2,13 @@
 #define _TRACE_IRQ_H
 
 #include <linux/tracepoint.h>
-#include <linux/interrupt.h>
 
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM irq
 
+struct irqaction;
+struct softirq_action;
+
 /**
  * irq_handler_entry - called immediately before the irq action handler
  * @irq: irq number
@@ -128,6 +130,29 @@ TRACE_EVENT(softirq_exit,
 	TP_printk("softirq=%d action=%s", __entry->vec, __get_str(name))
 );
 
+/**
+ * softirq_raise - called immediately when a softirq is raised
+ * @nr: softirq vector number
+ */
+TRACE_EVENT(softirq_raise,
+
+	TP_PROTO(unsigned int nr),
+
+	TP_ARGS(nr),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	nr			)
+		__string(	name,		softirq_to_name[nr]	)
+	),
+
+	TP_fast_assign(
+		__entry->nr	= nr;
+		__assign_str(name, softirq_to_name[nr]);
+	),
+
+	TP_printk("softirq=%u action=%s", __entry->nr, __get_str(name))
+);
+
 #endif /*  _TRACE_IRQ_H */
 
 /* This part must be outside protection */
-- 
1.6.1.2