tracing: introduce TRACE_EVENT_NOP()

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>

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 9c3186578ce06d2b872e6e93ad1da0e27cf36152..86b019aa28398fdf40748b30aeedd4cc8c6faa21 100644 (file)
--- 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 cb30c5532144883c7f534a5d7340bb294b49b998..bd75f97867b99a64ba0706a516cb06f0e4cc5a42 100644 (file)
--- 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