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Message-ID: <CAEf4BzZA30dEOxqtwWcMsGLLU0na77rmRANMMYQaNJ8D8o5-bQ@mail.gmail.com>
Date: Mon, 28 Oct 2024 13:19:08 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
Thomas Gleixner <tglx@...utronix.de>, Michael Jeanson <mjeanson@...icios.com>,
Masami Hiramatsu <mhiramat@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
Alexei Starovoitov <ast@...nel.org>, Yonghong Song <yhs@...com>, "Paul E . McKenney" <paulmck@...nel.org>,
Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Namhyung Kim <namhyung@...nel.org>,
bpf@...r.kernel.org, Joel Fernandes <joel@...lfernandes.org>,
Jordan Rife <jrife@...gle.com>
Subject: Re: [RFC PATCH v4 2/4] tracing: Introduce tracepoint_is_faultable()
On Mon, Oct 28, 2024 at 12:11 PM Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
>
> Introduce a "faultable" flag within the extended structure to know
> whether a tracepoint needs rcu tasks trace grace period before reclaim.
> This can be queried using tracepoint_is_faultable().
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Michael Jeanson <mjeanson@...icios.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Yonghong Song <yhs@...com>
> Cc: Paul E. McKenney <paulmck@...nel.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> Cc: bpf@...r.kernel.org
> Cc: Joel Fernandes <joel@...lfernandes.org>
> Cc: Jordan Rife <jrife@...gle.com>
> ---
> include/linux/tracepoint-defs.h | 2 ++
> include/linux/tracepoint.h | 24 ++++++++++++++++++++++++
> include/trace/define_trace.h | 2 +-
> 3 files changed, 27 insertions(+), 1 deletion(-)
>
LGTM
Acked-by: Andrii Nakryiko <andrii@...nel.org>
> diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
> index 967c08d9da84..aebf0571c736 100644
> --- a/include/linux/tracepoint-defs.h
> +++ b/include/linux/tracepoint-defs.h
> @@ -32,6 +32,8 @@ struct tracepoint_func {
> struct tracepoint_ext {
> int (*regfunc)(void);
> void (*unregfunc)(void);
> + /* Flags. */
> + unsigned int faultable:1;
> };
>
> struct tracepoint {
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 83dc24ee8b13..259f0ab4ece6 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -104,6 +104,12 @@ void for_each_tracepoint_in_module(struct module *mod,
> * tracepoint_synchronize_unregister must be called between the last tracepoint
> * probe unregistration and the end of module exit to make sure there is no
> * caller executing a probe when it is freed.
> + *
> + * An alternative is to use the following for batch reclaim associated
> + * with a given tracepoint:
> + *
> + * - tracepoint_is_faultable() == false: call_rcu()
> + * - tracepoint_is_faultable() == true: call_rcu_tasks_trace()
> */
> #ifdef CONFIG_TRACEPOINTS
> static inline void tracepoint_synchronize_unregister(void)
> @@ -111,9 +117,17 @@ static inline void tracepoint_synchronize_unregister(void)
> synchronize_rcu_tasks_trace();
> synchronize_rcu();
> }
> +static inline bool tracepoint_is_faultable(struct tracepoint *tp)
> +{
> + return tp->ext && tp->ext->faultable;
> +}
> #else
> static inline void tracepoint_synchronize_unregister(void)
> { }
> +static inline bool tracepoint_is_faultable(struct tracepoint *tp)
> +{
> + return false;
> +}
> #endif
>
> #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
> @@ -345,6 +359,15 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> struct tracepoint_ext __tracepoint_ext_##_name = { \
> .regfunc = _reg, \
> .unregfunc = _unreg, \
> + .faultable = false, \
> + }; \
> + __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
> +
> +#define DEFINE_TRACE_SYSCALL(_name, _reg, _unreg, _proto, _args) \
> + struct tracepoint_ext __tracepoint_ext_##_name = { \
> + .regfunc = _reg, \
> + .unregfunc = _unreg, \
> + .faultable = true, \
> }; \
> __DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
>
> @@ -389,6 +412,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> #define __DECLARE_TRACE_SYSCALL __DECLARE_TRACE
>
> #define DEFINE_TRACE_FN(name, reg, unreg, proto, args)
> +#define DEFINE_TRACE_SYSCALL(name, reg, unreg, proto, args)
> #define DEFINE_TRACE(name, proto, args)
> #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
> #define EXPORT_TRACEPOINT_SYMBOL(name)
> diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
> index ff5fa17a6259..63fea2218afa 100644
> --- a/include/trace/define_trace.h
> +++ b/include/trace/define_trace.h
> @@ -48,7 +48,7 @@
>
> #undef TRACE_EVENT_SYSCALL
> #define TRACE_EVENT_SYSCALL(name, proto, args, struct, assign, print, reg, unreg) \
> - DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args))
> + DEFINE_TRACE_SYSCALL(name, reg, unreg, PARAMS(proto), PARAMS(args))
>
> #undef TRACE_EVENT_NOP
> #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print)
> --
> 2.39.5
>
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