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Date:	Mon, 15 Jul 2013 00:55:22 +0200
From:	Oliver Schinagl <oliver+list@...inagl.nl>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	linux-kernel@...r.kernel.org, linux@...ck-us.net,
	khali@...ux-fr.org
Subject: Re: [PATCH v2 2/7] sysfs.h: add ATTRIBUTE_GROUPS() macro

Greg,

Haven't heard anything about this v2 patch, I know you are very busy but 
with the merge window closing today/yesterday just wondering about the 
status of it all.

Oliver

On 11-07-13 22:55, Oliver Schinagl wrote:
> On 07/11/13 22:26, Greg Kroah-Hartman wrote:
>> On Thu, Jul 11, 2013 at 10:09:11PM +0200, Oliver Schinagl wrote:
>>> On 07/11/13 19:06, Greg Kroah-Hartman wrote:
>>>> On Thu, Jul 11, 2013 at 01:58:29PM +0200, Oliver Schinagl wrote:
>>>>> On 11-07-13 02:36, Greg Kroah-Hartman wrote:
>>>>>> To make it easier for driver subsystems to work with attribute 
>>>>>> groups,
>>>>>> create the ATTRIBUTE_GROUPS macro to remove some of the repetitive
>>>>>> typing for the most common use for attribute groups.
>>>>> But binary groups are discriminated against :(
>>>>
>>>> Yes, as they are "rarer" by far, as they should be.  binary sysfs 
>>>> files
>>>> should almost never be used, as they are only "pass-through" files to
>>>> the hardware, so I want to see you do more work in order to use 
>>>> them, as
>>>> they should not be created lightly.
>>> I guess I can see a valid reason here, but they are only helper
>>> macro's making life easier for people who do need to use these and
>>> are on par with the non-binary versions. And we already have quite
>>> some binary attributes, probably far less then normal ones :)
>>
>> I only count about 100 valid binary files in the tree at the moment,
>> that's not really all that many to handle.
> 100 is quite a few :) But point taken.
>>
>>> Anyway, wouldn't all users be reviewed anyway? But I guess it's a
>>> small safety net to make it not TOO easy.
>>
>> exactly :)
> I aggree and this is a v2 that strips all the additional bits.
>
> A few comments left below.
>
>>
>>>>> The attached patch should help here.
>>>>
>>>> Can you give me an example of using these macros?  I seem to be 
>>>> lost in
>>>> them somehow, or maybe my morning coffee just hasn't kicked in...
>>> Yeah, I kinda added the whole shebang there :) I was trying being 
>>> helpful :(
>>>
>>>>
>>>>> I suppose one more additional helper wouldn't be bad to have:
>>>>>
>>>>> #define ATTRIBUTE_(BIN_)GROUPS_R[O/W](_name(, _size)) \
>>>>> ATTRIBUTE_(BIN_)ATTR_R[O/W](_name, _size); \
>>>>> ATTRIBUTE_(BIN_)GROUPS(_name)
>>>>
>>>> Would that ever be needed?
>>> Of ourse, by the lazy :)
>>>
>>> I think now you create an attribute in a group as this (with this 
>>> patch):
>>>
>>> ATTRIBUTE_ATTR_RO(name, SIZE);
>>
>> but "raw" attributes are rare, you really want a "device", "class", or
>> "bus" attribute, right?
> I suppose so, But I got stuck in the rare case some how initially. I 
> registered my driver with module_platform_driver(); and in that struct 
> i had the "device_driver" which had a group attribute so I used that. 
> I already learned from maxime that that is the wrong way :) and 
> hopefully I'll figure out what the right way will be soon ;)
>
>>
>>> ATTRIBUTE_GROUPS(name);
>>>
>>> .group = name;
>>>
>>> After that last addition, you'd simply do:
>>> ATTRIBUTE_GROUPS_RO(name);
>>>
>>> .group = name;
>>>
>>> saves a whole line :)
>>
>> Not worth it :)
>>
>>>>> >From 003ab7a74ff689daa6934e7bc50c498b2d35a1cc Mon Sep 17 00:00:00 
>>>>> 2001
>>>>> From: Oliver Schinagl <oliver@...inagl.nl>
>>>>> Date: Thu, 11 Jul 2013 13:48:18 +0200
>>>>> Subject: [PATCH] sysfs: add more helper macro's for 
>>>>> (bin_)attribute(_groups)
>>>>>
>>>>> With the recent changes to sysfs there's various helper macro's.
>>>>> However there's no RW, RO BIN_ helper macro's. This patch adds them.
>>>>>
>>>>> Additionally there are no BIN_ group helpers so there's that aswell
>>>>> Moreso, if both bin and normal attribute groups are used, there's a
>>>>> simple helper for that, though the naming code be better. _TXT_ 
>>>>> for the
>>>>> show/store ones and neither TXT or BIN for both, but that would 
>>>>> change
>>>>> things to extensivly.
>>>>>
>>>>> Finally there's also helpers for ATTRIBUTE_ATTRS.
>>>>>
>>>>> After this patch, create default attributes can be as easy as:
>>>>>
>>>>> ATTRIBUTE_(BIN_)ATTR_RO(name, SIZE);
>>>>> ATTRIBUTE_BIN_GROUPS(name);
>>>>>
>>>>> Signed-off-by: Oliver Schinagl <oliver@...inagl.nl>
>>>>> ---
>>>>>   include/linux/sysfs.h | 96 
>>>>> ++++++++++++++++++++++++++++++++++++++++++++-------
>>>>>   1 file changed, 84 insertions(+), 12 deletions(-)
>>>>>
>>>>> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
>>>>> index 2c3b6a3..0ebed11 100644
>>>>> --- a/include/linux/sysfs.h
>>>>> +++ b/include/linux/sysfs.h
>>>>> @@ -17,6 +17,7 @@
>>>>>   #include <linux/list.h>
>>>>>   #include <linux/lockdep.h>
>>>>>   #include <linux/kobject_ns.h>
>>>>> +#include <linux/stat.h>
>>>>>   #include <linux/atomic.h>
>>>>>
>>>>>   struct kobject;
>>>>> @@ -94,15 +95,32 @@ struct attribute_group {
>>>>>   #define __ATTR_IGNORE_LOCKDEP    __ATTR
>>>>>   #endif
>>>>>
>>>>> -#define ATTRIBUTE_GROUPS(name)                    \
>>>>> -static const struct attribute_group name##_group = {        \
>>>>> -    .attrs = name##_attrs,                    \
>>>>> +#define __ATTRIBUTE_GROUPS(_name)                \
>>>>> +static const struct attribute_group *_name##_groups[] = {    \
>>>>> +    &_name##_group,                        \
>>>>> +    NULL,                            \
>>>>> +}
>>>>> +
>>>>> +#define ATTRIBUTE_GROUPS(_name)                    \
>>>>> +static const struct attribute_group _name##_group = {        \
>>>>> +    .attrs = _name##_attrs,                    \
>>>>>   };                                \
>>>>> -static const struct attribute_group *name##_groups[] = {    \
>>>>> -    &name##_group,                        \
>>>>> +__ATTRIBUTE_GROUPS(_name)
>>>>> +
>>>>> +#define __ATTRIBUTE_ATTRS(_name)                \
>>>>> +struct bin_attribute *_name##_attrs[] = {            \
>>> typo here, scrap bin_ copy paste fail!
>>>
>>>>> + &_name##_attr,                        \
>>>>>       NULL,                            \
>>>>>   }
>>>>>
>>>>> +#define ATTRIBUTE_ATTR_RO(_name, _size)                \
>>>>> +struct attribute _name##_attr = __ATTR_RO(_name, _size);    \
>>>>> +__ATTRIBUTE_ATTRS(_name)
>>>>> +
>>>>> +#define ATTRIBUTE_ATTR_RW(_name, _size)                \
>>>>> +struct attribute _name##_attr = __ATTR_RW(_name, _size);    \
>>>>> +__ATTRIBUTE_ATTRS(_name)
>>>>
>>>> What do these two help out with?  "attribute attribute read-write" 
>>>> seems
>>>> a bit "clunky", don't you think? :)
>>> I aggree, but I tried to stick with the ATTRIBUTE_GROUP naming and
>>> that's the best I could come up with.
>>>
>>> Unless I completely misunderstood (which isn't all that unlikely)
>>> the following is needed to create a group using a .group.
>>>
>>> So you pass group an array of attribute_group pointers. The
>>> ATTRIBUTE_GROUPS helps there, right? It saves the typing of creating
>>> the array of groups and adding groups to that.
>>>
>>> So a group consists of an array of attributes if I understood right
>>> and that array needs to be filled with pointers attributes? well
>>> those ATTRIBUTE_ATTR's do just that. Granted, maybe the naming is
>>> poor, but just ATTRS() felt to short.
>>
>> Here's an example of a file I converted to use the ATTRIBUTE_GROUP()
>> macro attached below (net/wireless/sysfs).  As is, it's an increase of
>> only 2 lines to the file overall, which is about normal for the
>> conversion.  As you can see, you still need a list of attributes (which
>> someone has already said I need another macro for, to stop typing
>> "&dev_attr*.attr" all the time).
>>
>> With your macros, how would a file be converted to use them? Perhaps
>> that will help explain things to me better.
> Heh, they can't I don't think.
>
>>
>>
>>>>> +#define ATTRIBUTE_BIN_GROUPS(_name)                    \
>>>>> +static const struct attribute_group _name##_bin_group = {        \
>>>>> +    .bin_attrs = _name##_bin_attrs,                    \
>>>>> +};                                    \
>>>>> +__ATTRIBUTE_BIN_GROUPS(_name)
>>> This is the equiv. of ATTRIBUTE_GROUPS(_name) which creates an
>>> attribute group, with only a binary attribute instead.
>>
>> Again, binary files are rare, and should be rare, don't make it too easy
>> to create them :)
>>
>>>>> +#define ATTRIBUTE_BIN_ATTR_RW(_name, _size)                \
>>>>> +struct bin_attribute _name##_bin_attr = __BIN_ATTR_RW(_name, 
>>>>> _size);    \
>>>>> +__ATTRIBUTE_BIN_ATTRS(_name)
>>> These I guess are the equivialent what ATTRIBUTE_GROUP is for
>>> groups, but now for the attributes that go in groups?
>>>
>>>>
>>>> Can you show me how these would be used in a real-world example?
>>> Well my real world is currently limited by my own driver. If I may
>>> copy paste from there:
>>>
>>> ATTRIBUTE_BIN_ATTR_RO(sunxi_sid, SID_SIZE);
>>> ATTRIBUTE_BIN_GROUPS(sunxi_sid);
>>>
>>> static struct platform_driver sunxi_sid_driver = {
>>>     .probe = sunxi_sid_probe,
>>>     .remove = sunxi_sid_remove,
>>>     .driver = {
>>>         .name = DRV_NAME,
>>>         .owner = THIS_MODULE,
>>>         .of_match_table = sunxi_sid_of_match,
>>>         .groups = sunxi_sid_bin_groups,
>>>     },
>>> };
>>> module_platform_driver(sunxi_sid_driver);
>>>
>>> But if you say, you want to be a little less complete, we can drop
>>> ATTRIBUTE_BIN_ATTR_R[OW]() forcing you to do this instead:
>>>
>>> struct bin_attribute sunxi_sid_bin_attr = __BIN_ATTR_RO(eeprom, 
>>> SID_SIZE);
>>>
>>> struct bin_attribute *sunxi_sid_bin_attrs[] = {
>>>     &sunxi_sid_bin_attr,
>>>     NULL,
>>> };
>>>
>>> Which requires some manual labor yet still has the __BIN_ATTR_R[OW]
>>> macro's to help with some of the more tedious work and allowing you
>>> to name the binary attributes nicer?
>>
>> BIN_ATTR_RO() is fine, I'd stick with that for now, it's getting
>> confusing enough as-is :)
> Agreed and attached.
>
>>
>> thanks,
>>
>> greg k-h
>>
>

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