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Date:   Mon, 15 Jun 2020 15:28:56 +0200
From:   Petr Mladek <pmladek@suse.com>
To:     Jim Cromie <jim.cromie@gmail.com>
Cc:     jbaron@akamai.com, linux-kernel@vger.kernel.org,
        akpm@linuxfoundation.org, gregkh@linuxfoundation.org,
        linux@rasmusvillemoes.dk
Subject: Re: [PATCH v2 09/24] dyndbg: add maybe(str,"") macro to reduce code
Message-ID: <20200615132856.GF31238@alley>
References: <20200613155738.2249399-1-jim.cromie@gmail.com>
 <20200613155738.2249399-10-jim.cromie@gmail.com>
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On Sat 2020-06-13 09:57:23, Jim Cromie wrote:
> reduce word count via macro, no actual object change.
> 
> OTOH, maybe() could be scrubbed if printk's default printing (iirc) of
> "(null)" pointers is deemed appropriate for the log-msg.
> ---
>  lib/dynamic_debug.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 31d3be30776e..20b712652ee4 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -114,6 +114,7 @@ do {								\
>  #define vpr_info(fmt, ...)	vnpr_info(1, fmt, ##__VA_ARGS__)
>  #define v2pr_info(fmt, ...)	vnpr_info(2, fmt, ##__VA_ARGS__)
>  
> +#define maybe(str, empty)	( str ? str : empty )
>  static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>  {
>  	/* trim any trailing newlines */
> @@ -127,10 +128,10 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>  
>  	vpr_info("%s: func=\"%s\" file=\"%s\" module=\"%s\" format=\"%.*s\" lineno=%u-%u\n",
>  		 msg,
> -		 query->function ? query->function : "",
> -		 query->filename ? query->filename : "",
> -		 query->module ? query->module : "",
> -		 fmtlen, query->format ? query->format : "",
> +		 maybe(query->function, ""),
> +		 maybe(query->filename, ""),
> +		 maybe(query->module, ""),
> +		 fmtlen, maybe(query->format, ""),

From my POV this makes the code less readable. Open coding is much
more clear than an ambiguous macro name.

Best Regards,
Petr