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Message-ID: <0ed6de5e-5b47-30cb-68fa-ce6ee7c839a8@quicinc.com>
Date:   Mon, 23 Oct 2023 15:38:48 +0530
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Subject: Re: [PATCH] tracing/histograms: Simplify last_cmd_set()
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To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <kernel-janitors@vger.kernel.org>,
        <linux-trace-kernel@vger.kernel.org>
References: <30b6fb04dadc10a03cc1ad08f5d8a93ef623a167.1697899346.git.christophe.jaillet@wanadoo.fr>
From:   Mukesh Ojha <quic_mojha@quicinc.com>
In-Reply-To: <30b6fb04dadc10a03cc1ad08f5d8a93ef623a167.1697899346.git.christophe.jaillet@wanadoo.fr>
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On 10/21/2023 8:12 PM, Christophe JAILLET wrote:
> Turn a kzalloc()+strcpy()+strncat() into an equivalent and less verbose
> kasprintf().
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
>   kernel/trace/trace_events_hist.c | 11 ++---------
>   1 file changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index d06938ae0717..1abc07fba1b9 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -774,23 +774,16 @@ static void last_cmd_set(struct trace_event_file *file, char *str)
>   {
>   	const char *system = NULL, *name = NULL;
>   	struct trace_event_call *call;
> -	int len;
>   
>   	if (!str)
>   		return;
>   
> -	/* sizeof() contains the nul byte */
> -	len = sizeof(HIST_PREFIX) + strlen(str);
>   	kfree(last_cmd);
> -	last_cmd = kzalloc(len, GFP_KERNEL);
> +
> +	last_cmd = kasprintf(GFP_KERNEL, HIST_PREFIX "%s", str);
>   	if (!last_cmd)
>   		return;
>   
> -	strcpy(last_cmd, HIST_PREFIX);
> -	/* Again, sizeof() contains the nul byte */
> -	len -= sizeof(HIST_PREFIX);
> -	strncat(last_cmd, str, len);

LGTM, careful optimization., Thanks.
Reviewed-by: Mukesh ojha <quic_mojha@quicinc.com>


-Mukesh

> -
>   	if (file) {
>   		call = file->event_call;
>   		system = call->class->system;