Re: [PATCH v9 1/5] rust: add generic static_key_false

[Josh Poimboeuf]

On Tue, Oct 01, 2024 at 01:29:58PM +0000, Alice Ryhl wrote:
> Add just enough support for static key so that we can use it from
> tracepoints. Tracepoints rely on `static_key_false` even though it is
> deprecated, so we add the same functionality to Rust.

Instead of extending the old deprecated static key interface into Rust,
can we just change tracepoints to use the new one?

/me makes a note to go convert the other users...

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Subject: [PATCH] tracepoints: Use new static branch API

The old static key API based on 'struct static_key' is deprecated.
Convert tracepoints to use the new API.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 include/linux/tracepoint-defs.h | 4 ++--
 include/linux/tracepoint.h      | 8 ++++----
 kernel/tracepoint.c             | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
index 4dc4955f0fbf..60a6e8314d4c 100644
--- a/include/linux/tracepoint-defs.h
+++ b/include/linux/tracepoint-defs.h
@@ -31,7 +31,7 @@ struct tracepoint_func {
 
 struct tracepoint {
 	const char *name;		/* Tracepoint name */
-	struct static_key key;
+	struct static_key_false key;
 	struct static_call_key *static_call_key;
 	void *static_call_tramp;
 	void *iterator;
@@ -83,7 +83,7 @@ struct bpf_raw_event_map {
 
 #ifdef CONFIG_TRACEPOINTS
 # define tracepoint_enabled(tp) \
-	static_key_false(&(__tracepoint_##tp).key)
+	static_branch_unlikely(&(__tracepoint_##tp).key)
 #else
 # define tracepoint_enabled(tracepoint) false
 #endif
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 6be396bb4297..ab5162fc3e4a 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -228,7 +228,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 #define __DECLARE_TRACE_RCU(name, proto, args, cond)			\
 	static inline void trace_##name##_rcuidle(proto)		\
 	{								\
-		if (static_key_false(&__tracepoint_##name.key))		\
+		if (static_branch_unlikely(&__tracepoint_##name.key))	\
 			__DO_TRACE(name,				\
 				TP_ARGS(args),				\
 				TP_CONDITION(cond), 1);			\
@@ -254,7 +254,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	extern struct tracepoint __tracepoint_##name;			\
 	static inline void trace_##name(proto)				\
 	{								\
-		if (static_key_false(&__tracepoint_##name.key))		\
+		if (static_branch_unlikely(&__tracepoint_##name.key))	\
 			__DO_TRACE(name,				\
 				TP_ARGS(args),				\
 				TP_CONDITION(cond), 0);			\
@@ -291,7 +291,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	static inline bool						\
 	trace_##name##_enabled(void)					\
 	{								\
-		return static_key_false(&__tracepoint_##name.key);	\
+		return static_branch_unlikely(&__tracepoint_##name.key);\
 	}
 
 /*
@@ -308,7 +308,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 	struct tracepoint __tracepoint_##_name	__used			\
 	__section("__tracepoints") = {					\
 		.name = __tpstrtab_##_name,				\
-		.key = STATIC_KEY_INIT_FALSE,				\
+		.key = STATIC_KEY_FALSE_INIT,				\
 		.static_call_key = &STATIC_CALL_KEY(tp_func_##_name),	\
 		.static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
 		.iterator = &__traceiter_##_name,			\
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 8d1507dd0724..dc160cc0b616 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -358,7 +358,7 @@ static int tracepoint_add_func(struct tracepoint *tp,
 		tracepoint_update_call(tp, tp_funcs);
 		/* Both iterator and static call handle NULL tp->funcs */
 		rcu_assign_pointer(tp->funcs, tp_funcs);
-		static_key_enable(&tp->key);
+		static_branch_enable(&tp->key);
 		break;
 	case TP_FUNC_2:		/* 1->2 */
 		/* Set iterator static call */
@@ -414,7 +414,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
 		if (tp->unregfunc && static_key_enabled(&tp->key))
 			tp->unregfunc();
 
-		static_key_disable(&tp->key);
+		static_branch_disable(&tp->key);
 		/* Set iterator static call */
 		tracepoint_update_call(tp, tp_funcs);
 		/* Both iterator and static call handle NULL tp->funcs */
-- 
2.46.0