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

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Message-ID:
 <MN0PR20MB471701E2FEB9DBCDCDCD9D44F3382@MN0PR20MB4717.namprd20.prod.outlook.com>
Date: Sun, 31 Mar 2024 23:21:44 +0000
From: Mac Xu <mac.xxn@...look.com>
To: Joe Perches <joe@...ches.com>, Barry Song <21cnbao@...il.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
CC: "apw@...onical.com" <apw@...onical.com>, "broonie@...nel.org"
	<broonie@...nel.org>, "chenhuacai@...ngson.cn" <chenhuacai@...ngson.cn>,
	"chris@...kel.net" <chris@...kel.net>, "corbet@....net" <corbet@....net>,
	"dwaipayanray1@...il.com" <dwaipayanray1@...il.com>,
	"herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux@...ck-us.net" <linux@...ck-us.net>, "lukas.bulwahn@...il.com"
	<lukas.bulwahn@...il.com>, "sfr@...b.auug.org.au" <sfr@...b.auug.org.au>,
	"v-songbaohua@...o.com" <v-songbaohua@...o.com>, "workflows@...r.kernel.org"
	<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 Sun, 2024-03-31 at 13:46 +0000, Mac Xu wrote:
> > > 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
> >
> []
> > > 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
> >
> > Hi Joe,
> >
> > Thank you for your comments with insights, as you said, code block of line 6026 is a better place to
> > place this new logic, as it already handles the logic I'd wanted like extracting, splitting and trimming
> > the arguments, excluding the trailing comments etc.
> >
> > By placing the logic in the new place, code duplicates are reduced.
> >
> > Here's my new code (inserted from line 6044):
> > +# check if this is an unused argument
> > +        if ($define_stmt !~ /\b$arg\b/) {
> > +                WARN("UNUSED_ARG_IN_MACRO",
> Perhaps
>                                         WARN("MACRO_ARG_UNUSED",
>                         ...
> 
> to better match the others above it in the block:
> 
>                                         CHK("MACRO_ARG_REUSE",
> and
>                                         CHK("MACRO_ARG_PRECEDENCE",
> 
> Other than that trivial bit, seems ok.

Sure, updated, thank you!

+# check if this is an unused argument
+if ($define_stmt !~ /\b$arg\b/) {
+	WARN("MACRO_ARG_UNUSED",
+		"Argument '$arg' is not used in function-like macro\n" . "$herectx");
+}

Regards,
Xining