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

[Steven Rostedt]

On Tue, 1 Oct 2024 14:15:43 -0700
Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:

> 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?

Sure, care to send the patch properly, and I can add it to my queue.

-- Steve

> 
> /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 */