linux-kernel - Re: [PATCH] tracing/probes: Delete dead code in trace_eprobe_tp_update

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Message-ID: <20230706115216.72997ad5@gandalf.local.home>
Date:   Thu, 6 Jul 2023 11:52:16 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Dan Carpenter <dan.carpenter@...aro.org>,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] tracing/probes: Delete dead code in
 trace_eprobe_tp_update_arg()

On Sun, 2 Jul 2023 08:02:38 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> On Mon, 26 Jun 2023 16:35:06 +0300
> Dan Carpenter <dan.carpenter@...aro.org> wrote:
> 
> > This code was recently refactored and now the "ret" variable is always
> > zero.  Delete the check for non-zero.
> >   

Yep! The code use to be:

	if (ep->tp.args[i].code->op == FETCH_OP_TP_ARG) {
		ret = trace_eprobe_tp_arg_update(ep, i);
		if (ret)
			trace_probe_log_err(0, BAD_ATTACH_ARG);
	}

	/* Handle symbols "@" */
	if (!ret)
		ret = traceprobe_update_arg(&ep->tp.args[i]);

	return ret;
}

and is now:

        ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], &ctx);
        if (ret)
                return ret;

        /* Handle symbols "@" */
        if (!ret)
                ret = traceprobe_update_arg(&ep->tp.args[i]);

        return ret;
}

so that last ret check is redundant.

> 
> Good catch!
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org>

> 
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> > This code was changed in 1b8b0cd754cd (tracing/probes: Move event
> > parameter fetching code to common parser)  
> 
> OK, this will be picked to the 6.5 fix.

Thanks Masami and Dan,

-- Steve

> 
> Thank you!
> 
> > 
> >  kernel/trace/trace_eprobe.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> > 
> > diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> > index cb0077ba2b49..b5181d690b4d 100644
> > --- a/kernel/trace/trace_eprobe.c
> > +++ b/kernel/trace/trace_eprobe.c
> > @@ -797,10 +797,7 @@ static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[
> >  		return ret;
> >  
> >  	/* Handle symbols "@" */
> > -	if (!ret)
> > -		ret = traceprobe_update_arg(&ep->tp.args[i]);
> > -
> > -	return ret;
> > +	return traceprobe_update_arg(&ep->tp.args[i]);
> >  }
> >  
> >  static int trace_eprobe_parse_filter(struct trace_eprobe *ep, int argc, const char *argv[])
> > -- 
> > 2.39.2
> >   
> 
>