linux-kernel - Re: [PATCH] tracing: probe-events: Cleanup entry-arg storing code

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Message-ID: <20250306191404.69b0877e@gandalf.local.home>
Date: Thu, 6 Mar 2025 19:14:04 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: probe-events: Cleanup entry-arg storing code

On Mon,  3 Mar 2025 18:02:29 +0900
"Masami Hiramatsu (Google)" <mhiramat@...nel.org> wrote:

> +	/* Search the offset for the sprcified argnum. */
> +	for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i++) {
> +		if (earg->code[i].op != FETCH_OP_ARG || earg->code[i].param != argnum)
> +			continue;

I wonder if you can save a loop by changing this to:

		if (earg->code[i].op != FETCH_OP_ARG) {
			last_offset = earg->code[i].offset;
			continue;
		}

		if (earg->code[i].param != argnum)
			continue;


> +
> +		if (WARN_ON_ONCE(earg->code[i + 1].op != FETCH_OP_ST_EDATA))
> +			continue;
> +
> +		return earg->code[i + 1].offset;
>  	}
> -	return -ENOSPC;
> +	if (i >= earg->size - 1)
> +		return -ENOSPC;
> +
> +	/* Not found, append new entry if possible. */
> +	offset = get_entry_arg_max_offset(earg) + sizeof(unsigned long);

Then here you could use last_offset instead of running the loop again?

-- Steve


> +	store_entry_arg_at(&earg->code[i], argnum, offset);
> +	return offset;
>  }
>