tracing: Add DEFINE_EVENT_FN() macro

Each TRACE_EVENT() adds several helper functions. If two or more trace events
share the same structure and print format, they can also share most of these
helper functions and save a lot of space from duplicate code. This is why the
DECLARE_EVENT_CLASS() and DEFINE_EVENT() were created.

Some events require a trigger to be called at registering and unregistering of
the event and to do so they use TRACE_EVENT_FN().

If multiple events require a trigger, they currently have no choice but to use
TRACE_EVENT_FN() as there's no DEFINE_EVENT_FN() available. This unfortunately
causes a lot of wasted duplicate code created.

By adding a DEFINE_EVENT_FN(), these events can still use a
DECLARE_EVENT_CLASS() and then define their own triggers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/51C3236C.8030508@hds.com
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

3 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index f8e084d0fc77..ebeab360d851 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -378,6 +378,8 @@ static inline void tracepoint_synchronize_unregister(void)
 #define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
 #define DEFINE_EVENT(template, name, proto, args)               \
         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
+#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)\
+        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
         DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
 #define DEFINE_EVENT_CONDITION(template, name, proto,           \
diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index 1905ca8dd399..02e1003568a4 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -44,6 +44,10 @@
 #define DEFINE_EVENT(template, name, proto, args) \
         DEFINE_TRACE(name)
 
+#undef DEFINE_EVENT_FN
+#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \
+        DEFINE_TRACE_FN(name, reg, unreg)
+
 #undef DEFINE_EVENT_PRINT
 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
         DEFINE_TRACE(name)
@@ -91,6 +95,7 @@
 #undef TRACE_EVENT_CONDITION
 #undef DECLARE_EVENT_CLASS
 #undef DEFINE_EVENT
+#undef DEFINE_EVENT_FN
 #undef DEFINE_EVENT_PRINT
 #undef DEFINE_EVENT_CONDITION
 #undef TRACE_HEADER_MULTI_READ
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 19edd7facaa1..d615f78cc6b6 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -71,6 +71,10 @@
         static struct ftrace_event_call __used          \
         __attribute__((__aligned__(4))) event_##name
 
+#undef DEFINE_EVENT_FN
+#define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg)        \
+        DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
+
 #undef DEFINE_EVENT_PRINT
 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)  \
         DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))