linux-kernel - Re: [PATCH v2] tracing/eprobe: Iterate trace

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Date:   Fri, 11 Aug 2023 20:48:59 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Chuang Wang <nashuiliang@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tracing/eprobe: Iterate trace_eprobe directly

On Fri, 11 Aug 2023 16:12:39 +0800
Chuang Wang <nashuiliang@...il.com> wrote:

> Refer to the description in [1], we can skip "container_of()" following
> "list_for_each_entry()" by using "list_for_each_entry()" with
> "struct trace_eprobe" and "tp.list".
> 
> Also, this patch defines "for_each_trace_eprobe_on_trace_probe" to
> simplify the code of the same logic.
> 
> [1] https://lore.kernel.org/all/CAHk-=wjakjw6-rDzDDBsuMoDCqd+9ogifR_EE1F0K-jYek1CdA@mail.gmail.com/
> 

This looks good to me.

Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thanks!

> Signed-off-by: Chuang Wang <nashuiliang@...il.com>
> ---
> v1 -> v2:
> - add "for_each_trace_eprobe_on_trace_probe" as suggested by Masami
> 
> v0 -> v1:
> - remove "Fixes" in the commit information.
> 
>  kernel/trace/trace_eprobe.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index a0a704ba27db..b7c6179f8b7f 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -41,6 +41,10 @@ struct eprobe_data {
>  	struct trace_eprobe	*ep;
>  };
>  
> +
> +#define for_each_trace_eprobe_on_trace_probe(ep, _tp) \
> +	list_for_each_entry(ep, trace_probe_probe_list(_tp), tp.list)
> +
>  static int __trace_eprobe_create(int argc, const char *argv[]);
>  
>  static void trace_event_probe_cleanup(struct trace_eprobe *ep)
> @@ -640,7 +644,7 @@ static int disable_eprobe(struct trace_eprobe *ep,
>  static int enable_trace_eprobe(struct trace_event_call *call,
>  			       struct trace_event_file *file)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_eprobe *ep;
>  	bool enabled;
>  	int ret = 0;
> @@ -662,8 +666,7 @@ static int enable_trace_eprobe(struct trace_event_call *call,
>  	if (enabled)
>  		return 0;
>  
> -	list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -		ep = container_of(pos, struct trace_eprobe, tp);
> +	for_each_trace_eprobe_on_trace_probe(ep, tp) {
>  		ret = enable_eprobe(ep, file);
>  		if (ret)
>  			break;
> @@ -680,8 +683,7 @@ static int enable_trace_eprobe(struct trace_event_call *call,
>  			 */
>  			WARN_ON_ONCE(ret != -ENOMEM);
>  
> -			list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -				ep = container_of(pos, struct trace_eprobe, tp);
> +			for_each_trace_eprobe_on_trace_probe(ep, tp) {
>  				disable_eprobe(ep, file->tr);
>  				if (!--cnt)
>  					break;
> @@ -699,7 +701,7 @@ static int enable_trace_eprobe(struct trace_event_call *call,
>  static int disable_trace_eprobe(struct trace_event_call *call,
>  				struct trace_event_file *file)
>  {
> -	struct trace_probe *pos, *tp;
> +	struct trace_probe *tp;
>  	struct trace_eprobe *ep;
>  
>  	tp = trace_probe_primary_from_call(call);
> @@ -716,10 +718,8 @@ static int disable_trace_eprobe(struct trace_event_call *call,
>  		trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
>  
>  	if (!trace_probe_is_enabled(tp)) {
> -		list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> -			ep = container_of(pos, struct trace_eprobe, tp);
> +		for_each_trace_eprobe_on_trace_probe(ep, tp)
>  			disable_eprobe(ep, file->tr);
> -		}
>  	}
>  
>   out:
> -- 
> 2.39.2
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>