linux-kernel - Re: [PATCH v3 3/5] tracing: Use __free() for kprobe events to cleanup

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Message-ID: <20250107104231.06eeaca8@gandalf.local.home>
Date: Tue, 7 Jan 2025 10:42:31 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Anil S Keshavamurthy
 <anil.s.keshavamurthy@...el.com>, "David S . Miller" <davem@...emloft.net>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Oleg Nesterov
 <oleg@...hat.com>, Tzvetomir Stoyanov <tz.stoyanov@...il.com>, Naveen N Rao
 <naveen@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>, Jason Baron
 <jbaron@...mai.com>, Ard Biesheuvel <ardb@...nel.org>,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/5] tracing: Use __free() for kprobe events to
 cleanup

On Tue,  7 Jan 2025 20:50:35 +0900
"Masami Hiramatsu (Google)" <mhiramat@...nel.org> wrote:

> @@ -1898,7 +1899,8 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
>  			  bool is_return)
>  {
>  	enum probe_print_type ptype;
> -	struct trace_kprobe *tk;
> +	struct trace_kprobe *tk __free(free_trace_kprobe) = NULL;
> +	struct trace_probe *tp;
>  	int ret;
>  	char *event;
>  
> @@ -1929,19 +1931,16 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
>  
>  	ptype = trace_kprobe_is_return(tk) ?
>  		PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
> -	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0) {
> -		ret = -ENOMEM;
> -		goto error;
> -	}
> +	if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0)
> +		return ERR_PTR(-ENOMEM);
>  
>  	ret = __register_trace_kprobe(tk);
>  	if (ret < 0)
> -		goto error;
> +		return ERR_PTR(ret);
>  
> -	return trace_probe_event_call(&tk->tp);
> -error:
> -	free_trace_kprobe(tk);
> -	return ERR_PTR(ret);

> +	tp = &tk->tp;
> +	tk = NULL;	/* 'tk' is registered successfully, so do not free. */

I wonder if we could change the above to just:

	tp = &(no_free_ptr(tk)->tp);

?

-- Steve

> +	return trace_probe_event_call(tp);
>  }
>  
>  void destroy_local_trace_kprobe(struct trace_event_call *event_call)