Subject: Re: Expanding checkpatch for non-linux (specifically U-Boot) use
From: Joe Perches <joe@perches.com>
To: Graeme Russ <graeme.russ@gmail.com>, Andy Whitcroft <apw@canonical.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>, U-Boot Users <u-boot@lists.denx.de>
In-Reply-To: <4DB50854.8090700@gmail.com>
References: <4DB50854.8090700@gmail.com>
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Date: Sun, 24 Apr 2011 23:02:20 -0700
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On Mon, 2011-04-25 at 15:36 +1000, Graeme Russ wrote:
> There has been a bit of discussion lately on the U-Boot mailing list
> regarding the use of checkpatch for U-Boot patches (see
> http://lists.denx.de/pipermail/u-boot/2011-April/090954.html)
> 
> U-Boot uses the Linux coding style and checkpatch is therefore a very good
> tool for us to use to check style compliance. However, checkpatch has a few
> Linux specific checks which throw up false warnings for U-Boot patches like:
>
> WARNING: consider using kstrto* in preference to simple_strto*
> WARNING: Use #include <linux/$file> instead of <asm/$file>
> 
> Also, checkpatch seems to be checking not only patched lines, but context
> lines as well. There is a policy for U-Boot patches to not intermix
> whitespace / code cleanup changes and functional changes in in the same
> patch. So to achieve zero warnings and errors, the submitter is forced to
> create an additional code-cleanup patch in addition to the functionality
> patch. The code cleanup can end up being significantly larger than the
> functionality change which discourages casual submitters.
> 
> So I have a pretty simple question to ask of LKML - Will checkpatch patches
> to create a 'U-Boot' command-line option to explicitly filter out Linux
> specific warnings and errors ever be accepted into checkpatch, or will we
> be required to create and maintain a U-Boot specific version?
> 
> P.S. If you could please keep the U-Boot mailing list Cc'd, that would be
> appreciated

Hi Graeme.

Perhaps some sort of .checkpatch.conf file
could be introduced which could be linked to
specific types of errors/warnings/checks
that should be reported or ignored.

checkpatch has central routines to emit messages.

sub ERROR {
	if (report("ERROR: $_[0]\n")) {
		our $clean = 0;
		our $cnt_error++;
	}
}
sub WARN {
	if (report("WARNING: $_[0]\n")) {
		our $clean = 0;
		our $cnt_warn++;
	}
}
sub CHK {
	if ($check && report("CHECK: $_[0]\n")) {
		our $clean = 0;
		our $cnt_chk++;
	}
}

For instance, warnings could be changed to include
a new unique identifier for each message.

from
	WARN("Signed-off-by: is the preferred form\n" .
					$herecurr);
to
	WARN($WARN_SIGN_OFF,
	     "Signed-off-by: is the preferred form\n" .
					$herecurr);

and the ERROR/WARN/CHK routines could be extended to use
entries in the .conf file to enable/disable each message.

uboot could then use an appropriate .conf file.


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