linux-kernel - Re: [PATCH] scripts: checkpatch.pl add warning for dummy label

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Date:	Tue, 09 Sep 2014 08:43:00 -0700
From:	Joe Perches <joe@...ches.com>
To:	Nitin Kuppelur <nitinkuppelur@...il.com>
Cc:	akpm@...ux-foundation.org, josh@...htriplett.org, robh@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scripts: checkpatch.pl add warning for dummy label

On Tue, 2014-09-09 at 15:54 +0200, Nitin Kuppelur wrote:
> Added new warning DUMMY_LABEL in checkpatch.pl. This warns
> if return statement is encountered just after goto label target
> like "out:". In such scenario it is best to call "return;" directly
> instead of "goto out;"

I'm not sure this is desired/correct.

There are many functions written like:

return_type foo(...)
{
	[some initialization...]

	err = some_test(...);
	if (err)
		goto out;

	[...]

out:
	[some cleanup...]
	return err;
}

In many cases, a void function is a simple
variant of a non-void function and many people
like to see the same code "shape" in functions,
just without the init and cleanup bits.

> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -3798,10 +3798,14 @@ sub process {
>  		if ($sline =~ /^[ \+]}\s*$/ &&
>  		    $prevline =~ /^\+\treturn\s*;\s*$/ &&
>  		    $linenr >= 3 &&
> -		    $lines[$linenr - 3] =~ /^[ +]/ &&
> -		    $lines[$linenr - 3] !~ /^[ +]\s*$Ident\s*:/) {
> -			WARN("RETURN_VOID",
> -			     "void function return statements are not generally useful\n" . $hereprev);
> +		    $lines[$linenr - 3] =~ /^[ +]/) {
> +			if ($lines[$linenr - 3] !~ /^[ +]\s*$Ident\s*:/) {
> +				WARN("RETURN_VOID",
> +				     "void function return statements are not generally useful\n" . $hereprev);
> +			} elsif ($lines[$linenr - 3] =~ /^[ +]\s*$Ident\s*:/) {
> +				WARN("DUMMY_LABEL",
> +				     "labels doing nothing are not generally useful\n" . $hereprev);
> +			}
>                 }
>  
>  # if statements using unnecessary parentheses - ie: if ((foo == bar))



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