[PATCH] finally solve the bad sysfs-timing for all of us

On Tue, Sep 21, 2004 at 07:17:34PM +0200, Kay Sievers wrote:
> During the integration of HAL into the linux hotplug system, we dicover
> every week a new signaling path that fails cause of the delayed
> population of the sysfs files, which are connected by symlinks and
> appear in something like a random order in userspace.
>
> It's pretty complicated to understand the connection between all these
> files for all the different subsystems with all the exceptions, so most
> of the users simply sleep a few seconds, but that is not acceptable for
> our integration work.
>
> Here I try to get all the special knowledge about that behavior together
> and place that in a simple binary. That program _must_ run first of all
> other hotplug processsing and every later script, udev or HAL all can get
> rid of the wild guesses about the right time sysfs is ready.
>
> It will not only wait for the "dev"-file events we handle with udev, also
> for every /device-device with the corresponding bus link.
>
> It is provided as a patch against the current udev tree and a "install" will
> place the new program in the hotplug.d directory:
>
>   [kay@pim ~]$ tree /etc/hotplug.d/
>   /etc/hotplug.d/
>   `-- default
>       |-- 00-wait_for_sysfs.hotplug -> /sbin/wait_for_sysfs
>       |-- 10-udev.hotplug -> /sbin/udevsend
>       |-- 20-hal.hotplug -> /usr/libexec/hal.hotplug
>       |-- default.hotplug
>       `-- log.hotplug
>
>
> For now, it logs the result of the waiting to syslog, to catch any
> device, that needs special treatment. All newly discovered delay problems,
> device black/whitelist updates should go into that program and we may remove
> that kind of specialisation from all the other hotplug programs.
>
> Any patches, reports, testing is more than welcome.
>
> Sample debug:
>   Sep 21 18:44:07 localhost kernel: usb 3-2: new full speed USB device using address 12
>   Sep 21 18:44:07 localhost kernel: hub 3-2:1.0: USB hub found
>   Sep 21 18:44:07 localhost kernel: hub 3-2:1.0: 2 ports detected
>   Sep 21 18:44:07 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2'
>   Sep 21 18:44:07 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2:1.0'
>   Sep 21 18:44:08 localhost kernel: usb 3-2.1: new full speed USB device using address 13
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/class/usb/lp0'
>   Sep 21 18:44:08 localhost kernel: drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 13 if 0 alt 1 proto 2 vid 0x067B pid 0x2305
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.1/3-2.1:1.0'
>   Sep 21 18:44:08 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.1'
>   Sep 21 18:44:08 localhost udev: configured rule in '/etc/udev/rules.d/50-udev.rules' at line 29 applied, 'lp0' becomes 'usb/%k'
>   Sep 21 18:44:08 localhost udev: creating device node '/udev/usb/lp0'
>   Sep 21 18:44:09 localhost kernel: usb 3-2.2: new full speed USB device using address 14
>   Sep 21 18:44:09 localhost kernel: pl2303 3-2.2:1.0: PL-2303 converter detected
>   Sep 21 18:44:09 localhost kernel: usb 3-2.2: PL-2303 converter now attached to ttyUSB0
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2/3-2.2:1.0'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/devices/pci0000:00/0000:00:1d.1/usb3/3-2/3-2.2/3-2.2:1.0/ttyUSB0'
>   Sep 21 18:44:09 localhost 00-wait_for_sysfs.hotplug: result: waiting for sysfs successful '/class/tty/ttyUSB0'
>   Sep 21 18:44:09 localhost udev: creating device node '/udev/ttyUSB0'

New version with more devices excluded from /device-link saerch and
a better maching for device names.

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