[PATCH 1/3] tracing: introduce TRACE_EVENT_NONE()

[Yafang Shao <laoar.shao@gmail.com>]

Sometimes we want define a tracepoint as a do-nothing function.
So I introduce this TRACE_EVENT_NONE() for this kind of usage.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/linux/tracepoint.h   | 8 ++++++++
 include/trace/define_trace.h | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 9c31865..d00c5e6 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -548,4 +548,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 
 #define TRACE_EVENT_PERF_PERM(event, expr...)
 
+#define TRACE_EVENT_NONE(name, proto)				\
+	static inline void trace_##name(proto)			\
+	{ }							\
+	static inline bool trace_##name##_enabled(void)		\
+	{							\
+		return false;					\
+	}
+
 #endif /* ifdef TRACE_EVENT (see note above) */
diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index cb30c55..a833b6f 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -46,6 +46,9 @@
 		assign, print, reg, unreg)			\
 	DEFINE_TRACE_FN(name, reg, unreg)
 
+#undef TRACE_EVENT_NONE
+#define TRACE_EVENT_NONE(name, proto)
+
 #undef DEFINE_EVENT
 #define DEFINE_EVENT(template, name, proto, args) \
 	DEFINE_TRACE(name)
@@ -102,6 +105,7 @@
 #undef TRACE_EVENT_FN
 #undef TRACE_EVENT_FN_COND
 #undef TRACE_EVENT_CONDITION
+#undef TRACE_EVENT_NONE
 #undef DECLARE_EVENT_CLASS
 #undef DEFINE_EVENT
 #undef DEFINE_EVENT_FN
-- 
1.8.3.1