linux-kernel - [PATCH 1/2 v3] tracepoints: Remove unnecessary "data

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Message-ID: <20210208201050.768074128@goodmis.org>
Date:   Mon, 08 Feb 2021 15:09:23 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: [PATCH 1/2 v3] tracepoints: Remove unnecessary "data_args" macro parameter

From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>

While working on a clean up that would restructure the difference between
architectures that have static calls vs those that do not, I was stumbling
over the "data_args" parameter that includes "__data" in the arguments. The
issue was that one version didn't even need it, while the other one did.
Instead of injecting a "__data = NULL;" into the macro for the unneeded
version, just remove it completely.

The original idea behind data_args is that there may be a case of a
tracepoint with no arguments. But this is considered bad practice, and all
tracepoints should pass something to that location (that's what tracepoints
were created for).

Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 include/linux/tracepoint.h | 31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 966ed8980327..42bb5b753b33 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -160,13 +160,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 /*
  * it_func[0] is never NULL because there is at least one element in the array
  * when the array itself is non NULL.
- *
- * Note, the proto and args passed in includes "__data" as the first parameter.
- * The reason for this is to handle the "void" prototype. If a tracepoint
- * has a "void" prototype, then it is invalid to declare a function
- * as "(void *, void)".
  */
-#define __DO_TRACE(name, proto, args, cond, rcuidle)			\
+#define __DO_TRACE(name, args, cond, rcuidle)				\
 	do {								\
 		struct tracepoint_func *it_func_ptr;			\
 		int __maybe_unused __idx = 0;				\
@@ -194,7 +189,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 			rcu_dereference_raw((&__tracepoint_##name)->funcs); \
 		if (it_func_ptr) {					\
 			__data = (it_func_ptr)->data;			\
-			__DO_TRACE_CALL(name)(args);			\
+			__DO_TRACE_CALL(name)(__data, args);		\
 		}							\
 									\
 		if (rcuidle) {						\
@@ -206,17 +201,16 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	} while (0)
 
 #ifndef MODULE
-#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \
+#define __DECLARE_TRACE_RCU(name, proto, args, cond)			\
 	static inline void trace_##name##_rcuidle(proto)		\
 	{								\
 		if (static_key_false(&__tracepoint_##name.key))		\
 			__DO_TRACE(name,				\
-				TP_PROTO(data_proto),			\
-				TP_ARGS(data_args),			\
+				TP_ARGS(args),				\
 				TP_CONDITION(cond), 1);			\
 	}
 #else
-#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args)
+#define __DECLARE_TRACE_RCU(name, proto, args, cond)
 #endif
 
 /*
@@ -231,7 +225,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  * even when this tracepoint is off. This code has no purpose other than
  * poking RCU a bit.
  */
-#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
+#define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
 	extern int __traceiter_##name(data_proto);			\
 	DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name);	\
 	extern struct tracepoint __tracepoint_##name;			\
@@ -239,8 +233,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	{								\
 		if (static_key_false(&__tracepoint_##name.key))		\
 			__DO_TRACE(name,				\
-				TP_PROTO(data_proto),			\
-				TP_ARGS(data_args),			\
+				TP_ARGS(args),				\
 				TP_CONDITION(cond), 0);			\
 		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\
 			rcu_read_lock_sched_notrace();			\
@@ -249,7 +242,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 		}							\
 	}								\
 	__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args),		\
-		PARAMS(cond), PARAMS(data_proto), PARAMS(data_args))	\
+			    PARAMS(cond))				\
 	static inline int						\
 	register_trace_##name(void (*probe)(data_proto), void *data)	\
 	{								\
@@ -332,7 +325,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 
 
 #else /* !TRACEPOINTS_ENABLED */
-#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
+#define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
 	static inline void trace_##name(proto)				\
 	{ }								\
 	static inline void trace_##name##_rcuidle(proto)		\
@@ -412,14 +405,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 #define DECLARE_TRACE(name, proto, args)				\
 	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),		\
 			cpu_online(raw_smp_processor_id()),		\
-			PARAMS(void *__data, proto),			\
-			PARAMS(__data, args))
+			PARAMS(void *__data, proto))
 
 #define DECLARE_TRACE_CONDITION(name, proto, args, cond)		\
 	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),		\
 			cpu_online(raw_smp_processor_id()) && (PARAMS(cond)), \
-			PARAMS(void *__data, proto),			\
-			PARAMS(__data, args))
+			PARAMS(void *__data, proto))
 
 #define TRACE_EVENT_FLAGS(event, flag)
 
-- 
2.29.2