linux-kernel - Re: [PATCH] tracing: Remove redundant variable ret

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Date:   Fri, 28 May 2021 22:22:57 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Hyeonggon Yoo <42.hyeyoo@...il.com>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Tom Zanussi <zanussi@...nel.org>
Subject: Re: [PATCH] tracing: Remove redundant variable ret

On Fri, 28 May 2021 02:14:49 +0900
Hyeonggon Yoo <42.hyeyoo@...il.com> wrote:

> This variable saves return value of event_hist_trigger_func,
> but it's never read. So it's redundant.
> 
> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
> ---
>  kernel/trace/trace_events_hist.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index c1abd63f1d6c..414f2727d7a7 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -5225,12 +5225,11 @@ static void unregister_field_var_hists(struct hist_trigger_data *hist_data)
>  	struct trace_event_file *file;
>  	unsigned int i;
>  	char *cmd;
> -	int ret;
>  
>  	for (i = 0; i < hist_data->n_field_var_hists; i++) {
>  		file = hist_data->field_var_hists[i]->hist_data->event_file;
>  		cmd = hist_data->field_var_hists[i]->cmd;
> -		ret = event_hist_trigger_func(&trigger_hist_cmd, file,
> +		event_hist_trigger_func(&trigger_hist_cmd, file,
>  					      "!hist", "hist", cmd);

I wonder if instead we should add:

		WARN_ON_ONCE(ret < 0);

-- Steve

>  	}
>  }