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

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:

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On Tue, Dec 19, 2017 at 10:15:07AM -0800, Joe Perches wrote:

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Convert DEVICE_ATTR uses to DEVICE_ATTR_RW where possible.

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diff --git a/sound/soc/omap/mcbsp.c b/sound/soc/omap/mcbsp.c

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@@ -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?

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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...  :)

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.

thanks,

greg k-h