linux-kernel - Re: [PATCH v3 2/5] tracing: Use __free() in trace

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Message-ID: <20250107103643.37a3b002@gandalf.local.home>
Date: Tue, 7 Jan 2025 10:36:43 -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 2/5] tracing: Use __free() in trace_probe for cleanup

On Tue,  7 Jan 2025 20:50:25 +0900
"Masami Hiramatsu (Google)" <mhiramat@...nel.org> wrote:

> @@ -1790,18 +1777,15 @@ int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf)
>  				       offsetof(struct file, f_path.dentry),
>  				       equal ? equal + 1 : tmp);
>  
> -		kfree(tmp);
> +		kfree(no_free_ptr(tmp));

I don't get this? You are telling the compiler not to free tmp, because you
decided to free it yourself? Why not just remove the kfree() here altogether?

-- Steve

>  		if (ret >= bufsize - used)
> -			goto nomem;
> +			return -ENOMEM;
>  		argv[i] = tmpbuf + used;
>  		used += ret + 1;
>  	}
>  
> -	*buf = tmpbuf;
> +	*buf = no_free_ptr(tmpbuf);
>  	return 0;
> -nomem:
> -	kfree(tmpbuf);
> -	return -ENOMEM;
>  }