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

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Date:	Mon, 10 Sep 2007 01:03:33 +0200
From:	"Kay Sievers" <kay.sievers@...y.org>
To:	"Anssi Hannula" <anssi.hannula@...il.com>
Cc:	"Dmitry Torokhov" <dtor@...ightbb.com>,
	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

On 9/8/07, Anssi Hannula <anssi.hannula@...il.com> wrote:
> There seem to be changes in sysfs input structure between 2.6.22 and
> 2.6.23-rc5 which cause some breakage.
>
> With 2.6.22:
>
> > # LC_ALL=C ls -l /sys/class/input/input4
> > total 0
> > drwxr-xr-x 2 root root    0 Sep  8 12:51 capabilities/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:48 device -> ../../../devices/platform/pcspkr/
> > drwxr-xr-x 2 root root    0 Sep  8 12:51 event4/
> > drwxr-xr-x 2 root root    0 Sep  8 12:51 id/
> > -r--r--r-- 1 root root 4096 Sep  8 19:48 modalias
> > -r--r--r-- 1 root root 4096 Sep  8 19:48 name
> > -r--r--r-- 1 root root 4096 Sep  8 19:48 phys
> > lrwxrwxrwx 1 root root    0 Sep  8 19:48 subsystem -> ../../../class/input/
> > --w------- 1 root root 4096 Sep  8 19:48 uevent
> > -r--r--r-- 1 root root 4096 Sep  8 19:48 uniq
>
> > # ls -l /sys/class/input/event4
> > lrwxrwxrwx 1 root root 0 Sep  8 19:48 /sys/class/input/event4 -> ../../class/input/input4/event4/
> > # ls -l /sys/class/input/event4/
> > total 0
> > -r--r--r-- 1 root root 4096 Sep  8 19:58 dev
> > lrwxrwxrwx 1 root root    0 Sep  8 19:58 device -> ../../../../devices/platform/pcspkr/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:58 subsystem -> ../../../../class/input/
> > --w------- 1 root root 4096 Sep  8 19:58 uevent
>
> With 2.6.23-rc5:
>
> > # ls -l /sys/class/input/input5
> > total 0
> > drwxr-xr-x 2 root root    0 Sep  8 19:47 capabilities/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:03 device -> ../../../devices/platform/pcspkr/
> > drwxr-xr-x 2 root root    0 Sep  8 19:47 id/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:47 input:event5 -> ../../../class/input/event5/
> > -r--r--r-- 1 root root 4096 Sep  8 19:03 modalias
> > -r--r--r-- 1 root root 4096 Sep  8 19:03 name
> > -r--r--r-- 1 root root 4096 Sep  8 19:47 phys
> > drwxr-xr-x 2 root root    0 Sep  8 19:47 power/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:03 subsystem -> ../../../class/input/
> > -rw-r--r-- 1 root root 4096 Sep  8 19:03 uevent
> > -r--r--r-- 1 root root 4096 Sep  8 19:47 uniq
>
> > # ls -l /sys/class/input/event5
> > total 0
> > -r--r--r-- 1 root root 4096 Sep  8 19:03 dev
> > lrwxrwxrwx 1 root root    0 Sep  8 19:03 device -> ../../../class/input/input5/
> > drwxr-xr-x 2 root root    0 Sep  8 19:48 power/
> > lrwxrwxrwx 1 root root    0 Sep  8 19:03 subsystem -> ../../../class/input/
> > -rw-r--r-- 1 root root 4096 Sep  8 19:03 uevent
>
> There are a few changes.
>
> There is no longer:
> /sys/class/input/eventX => /sys/class/input/inputX/eventX
> instead there is:
> /sys/class/inputX/input:eventX => /sys/class/input/eventX
> Notice the added "input:". I don't know if any software depends on this,
> though.
>
> 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

Thanks,
Kay
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