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Subject[RFC PATCH] Tracepoint: introduce tracepoint() API
Introduce:

tracepoint(event_name, arg1, arg2, ...)

while keeping the old tracepoint API in place, e.g.:

trace_event_name(arg1, arg2, ...)

This allows skipping parameter side-effects (pointer dereference,
function calls, ...) when the tracepoint is not dynamically activated.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index d530a44..c9c73f7 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -107,6 +107,12 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin,

#ifdef CONFIG_TRACEPOINTS

+#define tracepoint(name, args...) \
+ do { \
+ if (static_branch(&__tracepoint_##name.key)) \
+ __trace_##name(args); \
+ } while (0)
+
/*
* it_func[0] is never NULL because there is at least one element in the array
* when the array itself is non NULL.
@@ -144,13 +150,17 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin,
*/
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
extern struct tracepoint __tracepoint_##name; \
+ static inline void __trace_##name(proto) \
+ { \
+ __DO_TRACE(&__tracepoint_##name, \
+ TP_PROTO(data_proto), \
+ TP_ARGS(data_args), \
+ TP_CONDITION(cond)); \
+ } \
static inline void trace_##name(proto) \
{ \
if (static_branch(&__tracepoint_##name.key)) \
- __DO_TRACE(&__tracepoint_##name, \
- TP_PROTO(data_proto), \
- TP_ARGS(data_args), \
- TP_CONDITION(cond)); \
+ __trace_##name(args); \
} \
static inline int \
register_trace_##name(void (*probe)(data_proto), void *data) \
@@ -193,7 +203,12 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin,
EXPORT_SYMBOL(__tracepoint_##name)

#else /* !CONFIG_TRACEPOINTS */
+
+#define tracepoint(name, args...) __trace_##name(args)
+
#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
+ static inline void __trace_##name(proto) \
+ { } \
static inline void trace_##name(proto) \
{ } \
static inline int \
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com


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