linux-kernel - Re: [PATCH v2 1/2] lib: add sputchar() helper

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Date:   Sat, 04 Sep 2021 18:36:41 -0700
From:   Joe Perches <joe@...ches.com>
To:     Yury Norov <yury.norov@...il.com>, Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Chris Down <chris@...isdown.name>,
        Gilles Muller <Gilles.Muller@...ia.fr>,
        Ingo Molnar <mingo@...nel.org>,
        Jacob Keller <jacob.e.keller@...el.com>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Peter Zijlstra <peterz@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, cocci@...teme.lip6.fr
Subject: Re: [PATCH v2 1/2] lib: add sputchar() helper

On Sat, 2021-09-04 at 16:10 -0700, Yury Norov wrote:
> There are 47 occurrences of the code snippet like this:
> 	if (buf < end)
> 	        *buf = ' ';
> 	++buf;
> 
> This patch adds a helper function sputchar() to replace opencoding.
> It adds a lot to readability, and also saves 43 bytes of text on x86.

I think this patch does little to improve readability.

Perhaps make it void and use something like

	sputchar(*buf++, end, <whateverchar>);

Though the sputchar name doesn't seems particularly intelligible.

> +static inline char *sputchar(char *buf, const char *end, char c)
> +{
> +	if (buf < end)
> +		*buf = c;
> +
> +	return buf + 1;
> +}
> +
>  /*
>   * General tracing related utility functions - trace_printk(),
>   * tracing_on/tracing_off and tracing_start()/tracing_stop
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
[]
> @@ -335,12 +335,8 @@ static bool escape_space(unsigned char c, char **dst, char *end)
>  		return false;
>  	}
> 
> -	if (out < end)
> -		*out = '\\';
> -	++out;
> -	if (out < end)
> -		*out = to;
> -	++out;
> +	out = sputchar(out, end, '\\');
> +	out = sputchar(out, end, to);

etc...