linux-kernel - Re: [for-next][PATCH 4/5] tracing: Have the historgram use the result of str_has

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Date:   Sun, 23 Dec 2018 12:35:56 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joe Perches <joe@...ches.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, linux-sh@...r.kernel.org,
        Tom Zanussi <zanussi@...nel.org>, kernel-team@....com
Subject: Re: [for-next][PATCH 4/5] tracing: Have the historgram use the
 result of str_has_prefix() for len of prefix

On Sat, Dec 22, 2018 at 11:20:11AM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
> 
> As str_has_prefix() returns the length on match, we can use that for the
> updating of the string pointer instead of recalculating the prefix size.
> 
> Cc: Tom Zanussi  <zanussi@...nel.org>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
>  kernel/trace/trace_events_hist.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 0d878dcd1e4b..449d90cfa151 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -4342,12 +4342,13 @@ static int parse_actions(struct hist_trigger_data *hist_data)
>  	unsigned int i;
>  	int ret = 0;
>  	char *str;
> +	int len;
>  
>  	for (i = 0; i < hist_data->attrs->n_actions; i++) {
>  		str = hist_data->attrs->action_str[i];
>  
> -		if (str_has_prefix(str, "onmatch(")) {
> -			char *action_str = str + sizeof("onmatch(") - 1;
> +		if ((len = str_has_prefix(str, "onmatch("))) {
> +			char *action_str = str + len;

Ah you did it here.

Thanks,
Namhyung


>  
>  			data = onmatch_parse(tr, action_str);
>  			if (IS_ERR(data)) {
> @@ -4355,8 +4356,8 @@ static int parse_actions(struct hist_trigger_data *hist_data)
>  				break;
>  			}
>  			data->fn = action_trace;
> -		} else if (str_has_prefix(str, "onmax(")) {
> -			char *action_str = str + sizeof("onmax(") - 1;
> +		} else if ((len = str_has_prefix(str, "onmax("))) {
> +			char *action_str = str + len;
>  
>  			data = onmax_parse(action_str);
>  			if (IS_ERR(data)) {
> -- 
> 2.19.2
> 
>