Re: [-next PATCH 2/4] treewide: Use DEVICE_ATTR_RW

Joe Perches
2017-12-20T09:54:55Z

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@linuxfoundation.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