linux-kernel - [PATCH] tracepoint: reduce duplication of __DO_TRACE

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Message-ID: <20241212131237.1988409-1-aliceryhl@google.com>
Date: Thu, 12 Dec 2024 13:12:37 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	rust-for-linux@...r.kernel.org, Alice Ryhl <aliceryhl@...gle.com>
Subject: [PATCH] tracepoint: reduce duplication of __DO_TRACE_CALL

The logic for invoking __DO_TRACE_CALL was extracted to a static inline
function called __rust_do_trace_##name so that Rust can call it
directly. This logic does not include the static branch, to avoid a
function call when the tracepoint is disabled.

Since the C code needs to perform the same logic after checking the
static key, this logic is currently duplicated. Thus, remove this
duplication by having C call the static inline function too.

Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
---
 include/linux/tracepoint.h | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 76d9055b2cff..a351763e6965 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -218,7 +218,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 #define __DEFINE_RUST_DO_TRACE(name, proto, args)			\
 	notrace void rust_do_trace_##name(proto)			\
 	{								\
-		__rust_do_trace_##name(args);				\
+		__do_trace_##name(args);				\
 	}
 
 /*
@@ -268,41 +268,35 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 
 #define __DECLARE_TRACE(name, proto, args, cond, data_proto)		\
 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
-	static inline void __rust_do_trace_##name(proto)		\
+	static inline void __do_trace_##name(proto)			\
 	{								\
 		if (cond) {						\
 			guard(preempt_notrace)();			\
 			__DO_TRACE_CALL(name, TP_ARGS(args));		\
 		}							\
 	}								\
 	static inline void trace_##name(proto)				\
 	{								\
-		if (static_branch_unlikely(&__tracepoint_##name.key)) { \
-			if (cond) {					\
-				guard(preempt_notrace)();		\
-				__DO_TRACE_CALL(name, TP_ARGS(args));	\
-			}						\
-		}							\
+		if (static_branch_unlikely(&__tracepoint_##name.key))	\
+			__do_trace_##name(args);			\
 		if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) {		\
 			WARN_ONCE(!rcu_is_watching(),			\
 				  "RCU not watching for tracepoint");	\
 		}							\
 	}
 
 #define __DECLARE_TRACE_SYSCALL(name, proto, args, data_proto)		\
 	__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
-	static inline void __rust_do_trace_##name(proto)		\
+	static inline void __do_trace_##name(proto)			\
 	{								\
 		guard(rcu_tasks_trace)();				\
 		__DO_TRACE_CALL(name, TP_ARGS(args));			\
 	}								\
 	static inline void trace_##name(proto)				\
 	{								\
 		might_fault();						\
-		if (static_branch_unlikely(&__tracepoint_##name.key)) {	\
-			guard(rcu_tasks_trace)();			\
-			__DO_TRACE_CALL(name, TP_ARGS(args));		\
-		}							\
+		if (static_branch_unlikely(&__tracepoint_##name.key))	\
+			__do_trace_##name(args);			\
 		if (IS_ENABLED(CONFIG_LOCKDEP)) {			\
 			WARN_ONCE(!rcu_is_watching(),			\
 				  "RCU not watching for tracepoint");	\

base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4
-- 
2.47.0.338.g60cca15819-goog