linux-kernel - Re: [PATCH RFC] checkpatch: fix multi-statement macro checks

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Message-ID: <8e110121c89414ab1601071868dbcf410195a209.camel@perches.com>
Date:   Thu, 01 Oct 2020 06:17:21 -0700
From:   Joe Perches <joe@...ches.com>
To:     Dwaipayan Ray <dwaipayanray1@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        lukas.bulwahn@...il.com
Subject: Re: [PATCH RFC] checkpatch: fix multi-statement macro checks

On Thu, 2020-10-01 at 16:03 +0530, Dwaipayan Ray wrote:
> Checkpatch.pl doesn't have a check for excluding while (...) {...}
> blocks from MULTISTATEMENT_MACRO_USE_DO_WHILE error.
> 
> For example, running checkpatch.pl on the file mm/access.c in the
> kernel generates the following error:
> 
> ERROR: Macros with complex values should be enclosed in parentheses
> +#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\
> +	while (len >= sizeof(type)) {					\
> +		__get_kernel_nofault(dst, src, type, err_label);	\
> +		dst += sizeof(type);					\
> +		src += sizeof(type);					\
> +		len -= sizeof(type);					\
> +	}
> 
> The error is misleading for this case. Enclosing it in parantheses
> doesn't make any sense.

OK

> Checkpatch already has an exception list for such common macro types.
> Added a new exception for while (...) {...} style blocks to the same.
> This effectively fixed the wrong error message.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -5342,6 +5342,7 @@ sub process {
>  			    $dstat !~ /^\.$Ident\s*=/ &&				# .foo =
>  			    $dstat !~ /^(?:\#\s*$Ident|\#\s*$Constant)\s*$/ &&		# stringification #foo
>  			    $dstat !~ /^do\s*$Constant\s*while\s*$Constant;?$/ &&	# do {...} while (...); // do {...} while (...)
> +			    $dstat !~ /^while\s*$Constant\s*$Constant\s*$/ &&		# while (...) {...}

Did you try to output $dstat for some matching cases?
What was the $dstat value for the cases you tried?