[for-next][PATCH 17/19] tracing: introduce TRACE_EVENT_NOP()

Steven Rostedt
2019-04-04T01:38:31Z

From: Yafang Shao <laoar.shao@gmail.com>

Sometimes we want to define a tracepoint as a do-nothing function.
So I introduce TRACE_EVENT_NOP, DECLARE_EVENT_CLASS_NOP and
DEFINE_EVENT_NOP for this kind of usage.

Link: http://lkml.kernel.org/r/1553602391-11926-2-git-send-email-laoar.shao@gmail.com

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/tracepoint.h | 15 +++++++++++++++
include/trace/define_trace.h | 8 ++++++++
2 files changed, 23 insertions(+)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 9c3186578ce0..86b019aa2839 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -548,4 +548,19 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)

#define TRACE_EVENT_PERF_PERM(event, expr...)

+#define DECLARE_EVENT_NOP(name, proto, args) \
+ static inline void trace_##name(proto) \
+ { } \
+ static inline bool trace_##name##_enabled(void) \
+ { \
+ return false; \
+ }
+
+#define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) \
+ DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
+
+#define DECLARE_EVENT_CLASS_NOP(name, proto, args, tstruct, assign, print)
+#define DEFINE_EVENT_NOP(template, name, proto, args) \
+ DECLARE_EVENT_NOP(name, PARAMS(proto), PARAMS(args))
+
#endif /* ifdef TRACE_EVENT (see note above) */
diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index cb30c5532144..bd75f97867b9 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -46,6 +46,12 @@
assign, print, reg, unreg) \
DEFINE_TRACE_FN(name, reg, unreg)

+#undef TRACE_EVENT_NOP
+#define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)
+
+#undef DEFINE_EVENT_NOP
+#define DEFINE_EVENT_NOP(template, name, proto, args)
+
#undef DEFINE_EVENT
#define DEFINE_EVENT(template, name, proto, args) \
DEFINE_TRACE(name)
@@ -102,6 +108,8 @@
#undef TRACE_EVENT_FN
#undef TRACE_EVENT_FN_COND
#undef TRACE_EVENT_CONDITION
+#undef TRACE_EVENT_NOP
+#undef DEFINE_EVENT_NOP
#undef DECLARE_EVENT_CLASS
#undef DEFINE_EVENT
#undef DEFINE_EVENT_FN
--
2.20.1