linux-kernel - Re: [PATCH v4 2/2] scripts: checkpatch: check unused parameters for function-like macro

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Message-ID: <ef2c96e40bcf777535c9ff2405e4dc5b3138b27e.camel@perches.com>
Date: Thu, 28 Mar 2024 02:57:35 -0700
From: Joe Perches <joe@...ches.com>
To: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org, 
	linux-doc@...r.kernel.org
Cc: apw@...onical.com, broonie@...nel.org, chenhuacai@...ngson.cn, 
 chris@...kel.net, corbet@....net, dwaipayanray1@...il.com, 
 herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org,
 linux@...ck-us.net,  lukas.bulwahn@...il.com, mac.xxn@...look.com,
 sfr@...b.auug.org.au,  v-songbaohua@...o.com, workflows@...r.kernel.org,
 Max Filippov <jcmvbkbc@...il.com>
Subject: Re: [PATCH v4 2/2] scripts: checkpatch: check unused parameters for
 function-like macro

On Thu, 2024-03-28 at 15:21 +1300, Barry Song wrote:
> From: Xining Xu <mac.xxn@...look.com>
> 
> If function-like macros do not utilize a parameter, it might result in a
> build warning.  In our coding style guidelines, we advocate for utilizing
> static inline functions to replace such macros.  This patch verifies
> compliance with the new rule.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -6109,6 +6109,36 @@ sub process {
>  				WARN("TRAILING_SEMICOLON",
>  				     "macros should not use a trailing semicolon\n" . "$herectx");
>  			}
> +
> +			# match "\s*" rather than "\s+" after the balanced parens, as macro definition with arguments
> +			# is not required to have whitespace after arguments
> +			if ($dstat =~ /^\+\s*#\s*define\s+$Ident$balanced_parens\s*(\S+.*)(\/[\/*].*)?/) {

I think '(\/[\/*].*)?' doesn't do what you expect
perhaps '(\/[\/\*].*)?'
though I don't know why this should be capture group

> +				my $params = $1 || "";


> +				my $body = $2 || "";

Should never get the || "" as the 2nd capture group is not optional

> +
> +			    # get the individual params
> +				$params =~ tr/()//d;
> +				# remove leading and trailing whitespace
> +				$params =~ s/^\s+|\s+$//g;
> +
> +				$ctx =~ s/\n*$//;
> +				my $cnt = statement_rawlines($ctx);
> +				my $herectx = get_stat_here($linenr, $cnt, $here);
> +
> +				if ($params ne "") {

probably unnecessary

> +					my @paramList = split /,\s*/, $params;

please use split() with parentheses

> +					foreach my $param(@paramList) {

maybe
				foreach my $param (split(/,/, $params) {
					$param = trim($param);
					next if ($param =~ /\.\.\.$/);

> +						if ($param =~ /\.\.\.$/) {
> +							# if the param name ends with "...", skip the check
> +							next;
> +						}
> +						if ($body !~ /\b$param\b/) {
> +							WARN("UNUSED_PARAM_IN_MACRO",
> +								"Parameter '$param' is not used in function-like macro\n" . "$herectx");
> +						}
> +					}

It seems this logic is a bit redundant to existing
code and might be better added in the block that starts

(line 6026)
# check if any macro arguments are reused (ignore '...' and 'type')

as that already does each param in a #define and
ignores ... and type