linux-kernel - Re: sysfs change of input/event devices in 2.6.23rc breaks udev

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Date:	Sat, 15 Sep 2007 18:46:19 +0300
From:	Anssi Hannula <anssi.hannula@...il.com>
To:	Dmitry Torokhov <dtor@...ightbb.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <gregkh@...e.de>, Kay Sievers <kay.sievers@...y.org>,
	linux-input@...ey.karlin.mff.cuni.cz, linux-kernel@...r.kernel.org
Subject: Re: sysfs change of input/event devices in 2.6.23rc breaks udev

Dmitry Torokhov wrote:
> On Saturday 15 September 2007 04:05, Andrew Morton wrote:
>> On Mon, 10 Sep 2007 09:24:04 -0400 "Dmitry Torokhov" <dmitry.torokhov@...il.com> wrote:
>>
>>> On 9/10/07, Greg KH <gregkh@...e.de> wrote:
>>>> On Mon, Sep 10, 2007 at 01:28:47AM -0400, Dmitry Torokhov wrote:
>>>>> On Sunday 09 September 2007 19:03, Kay Sievers wrote:
>>>>>> On 9/8/07, Anssi Hannula <anssi.hannula@...il.com> wrote:
>>>>>>> However, the change that broke id_path of udev is that
>>>>>>> /sys/class/input/event5/device is now a symlink to the inputX directory
>>>>>>> instead of being the same as the device symlink in inputX directory,
>>>>>>> i.e. to ../../../devices/platform/pcspkr in this case.
>>>>>>>
>>>>>>> Udev id_path uses that directory to construct the ID_PATH variable.
>>>>>>> Should the sysfs structure be reverted or should udev be adapted to
>>>>>>> handle traversing /device symlink twice? I think the former, as there
>>>>>>> should be considerably more time to adapt udev for coming changes in sysfs.
>>>>>> Udev's path_id script is too dumb to follow the "device" link of
>>>>>> stacked class devices in the CONFIG_SYSFS_DEPRECATED=y layout. Does
>>>>>> this change fix it for you?
>>>>>>   http://git.kernel.org/?p=linux/hotplug/udev.git;a=commitdiff_plain;h=b1ac36ff5e3756cefc79967a26280056da31bf6f
>>>>>>
>>>>> Hmm, fixing udev is good but users will not get the change in time. I think we
>>>>> need to adjust SYSFS_DEPRECATED code to produce old results. Something like the
>>>>> patch below. I wonder what Greg would think...
>>>> Hm, I don't understand.  Didn't the original conversion of the input
>>>> layer by Kay not have this kind of problem?  What did your changes do
>>>> differently to cause this driver core change to be needed?
>>>>
>>> If I understand it correctly Kay's convesion had the same issue. With
>>> class devices "device" link points to class_dev->device instead of
>>> class_dev->parent. If you want to keep compatibility with old sysfs
>>> layout when moving from class devices to regular devices then you need
>>> to "skip" couple of parents till you get to "real" device. This only
>>> matters for input because this was the only subsystem with class
>>> devices stacked.
>>>
>> <wonders where the rest of this thread went to>
> 
> Limbo ;)
> 
> Anssi, could you please tell me if the patch fixes the issue on your box?

It does.

>> Did this userspace-visible post-2.6.22 regression get fixed?
>>
> 
> I'd like the patch to go through Greg if he is OK with it.
> 


-- 
Anssi Hannula
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