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

Greg Kroah-Hartman
2017-12-20T09:59:31Z

On Wed, Dec 20, 2017 at 01:54:41AM -0800, Joe Perches wrote:
> 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*

Heh, good point, but using get_maintainer.pl does put me at the top of
the list that you should be cc:ing:

$ ./scripts/get_maintainer.pl --file include/linux/sysfs.h
Greg Kroah-Hartman <gregkh@linuxfoundation.org> (commit_signer:3/3=100%,authored:2/3=67%,added_lines:7/8=88%)
Kate Stewart <kstewart@linuxfoundation.org> (commit_signer:1/3=33%)
Thomas Gleixner <tglx@linutronix.de> (commit_signer:1/3=33%)
Philippe Ombredanne <pombredanne@nexb.com> (commit_signer:1/3=33%)
Nick Desaulniers <nick.desaulniers@gmail.com> (commit_signer:1/3=33%,authored:1/3=33%,added_lines:1/8=12%,removed_lines:1/1=100%)
linux-kernel@vger.kernel.org (open list)

Anyway, I'll go add sysfs.h to the list, thanks for pointing it out.

> > 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
>

Ah, nice, I love perl :)

greg k-h