linux-kernel - Re: [-next PATCH 2/4] treewide: Use DEVICE_ATTR

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Date:   Wed, 20 Dec 2017 01:54:41 -0800
From:   Joe Perches <joe@...ches.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jarkko Nikula <jarkko.nikula@...mer.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Cezary Jackiewicz <cezary.jackiewicz@...il.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Sebastian Ott <sebott@...ux.vnet.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.vnet.ibm.com>,
        James Smart <james.smart@...adcom.com>,
        Dick Kennedy <dick.kennedy@...adcom.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Felipe Balbi <balbi@...nel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        David Airlie <airlied@...ux.ie>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jiri Slaby <jslaby@...e.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org,
        platform-driver-x86@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-fbdev@...r.kernel.org,
        alsa-devel@...a-project.org, linux-omap@...r.kernel.org
Subject: Re: [-next PATCH 2/4] treewide: Use DEVICE_ATTR_RW

On Wed, 2017-12-20 at 10:32 +0100, Greg Kroah-Hartman wrote:
> On Wed, Dec 20, 2017 at 01:24:44AM -0800, Joe Perches wrote:
> > On Wed, 2017-12-20 at 10:34 +0200, Jarkko Nikula wrote:
> > > On Tue, Dec 19, 2017 at 10:15:07AM -0800, Joe Perches wrote:
> > > > Convert DEVICE_ATTR uses to DEVICE_ATTR_RW where possible.
> > 
> > [] 
> > > > diff --git a/sound/soc/omap/mcbsp.c b/sound/soc/omap/mcbsp.c
> > 
> > []
> > > > @@ -854,7 +854,7 @@ static ssize_t dma_op_mode_store(struct device *dev,
> > > >  	return size;
> > > >  }
> > > >  
> > > > -static DEVICE_ATTR(dma_op_mode, 0644, dma_op_mode_show, dma_op_mode_store);
> > > > +static DEVICE_ATTR_RW(dma_op_mode);
> > > >  
> > > 
> > > While I can ack this part here if it helps generic cleanup effort I
> > > don't understart would it improve code readability in general? Mode 644
> > > is clear and don't need any grepping but for DEVICE_ATTR_RW() I had to go
> > > through all of these files in order to see what does it mean:
> 
> Yeah, 644 is "clear", but _RW() is even more clear.  Ideally I want to
> get rid of all of the "non-standard" users that set random modes of
> sysfs files, as we get it wrong too many times.  Using the "defaults" is
> much better.
> 
> > Are you suggesting that device.h (as that is where
> > DEVICE_ATTR and the other DEVICE_ATTR_<FOO> variants
> > are #defined) should have better comments for the
> > _<FOO> variants?
> > 
> > > DEVICE_ATTR_RW: include/linux/device.h
> > > __ATTR_RW: include/linux/sysfs.h
> > > S_IWUSR: include/uapi/linux/stat.h
> > > S_IRUGO: include/linux/stat.h
> > 
> > btw: patch 1/4 of the series does remove the uses of
> > S_<PERMS> from these macros in sysfs.h and converts
> > them to simple octal instead.
> 
> Why you didn't send that patch to the sysfs maintainer is a bit odd...  :)

So here's an opportunity for you:

The sysfs maintainer hasn't added include/linux/sysfs.h to
the list of maintained files...

DRIVER CORE, KOBJECTS, DEBUGFS AND SYSFS
M:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
S:	Supported
F:	Documentation/kobject.txt
F:	drivers/base/
F:	fs/debugfs/
F:	fs/sysfs/
F:	include/linux/debugfs.h
F:	include/linux/kobj*
F:	lib/kobj*

> I should be taking this whole series through my tree.  Joe, thanks for
> doing this in an automated way, I've been wanting to see this done for a
> long time.

btw: there are many uses of a reversed declaration style of DEVICE_ATTR

Here's another thing that could be done for more DEVICE_ATTR_<FOO> uses.

===

Some DEVICE_ATTR definitions use a reversed static function form from
the typical.  Convert them to use the more common macro form so it is
easier to grep for the style.

i.e.:
        static ssize_t show_<foo>(...)
and
        static ssize_t store_<foo>(...)

where the static function names in the DEVICE_ATTR_RW macro are reversed

        static ssize_t <foo>_show(...)
and
        static ssize_t <foo>_store(...)

Done with perl script

$ cat dev_attr_rw_backwards.perl
local $/;
while (<>) {
    my $file = $_;
    while ($file =~ m/\bDEVICE_ATTR\s*\(\s*(\w+)\s*,/g) {
        my $var = $1;
        if ($file =~ s/\bDEVICE_ATTR\s*\(\s*${var}\s*,\s*\(?(\s*S_IRUGO\s*\|\s*S
            $file =~ s/\bshow_${var}\b/${var}_show/g;
            $file =~ s/\bstore_${var}\b/${var}_store/g;
        }
    }
    print $file;
}

$ git grep --name-only -w DEVICE_ATTR | \
  xargs perl -i dev_attr_rw_backwards.perl