udev/ubuntu problem solved

[Andreas Jellinghaus <aj@dungeon.inka.de>]

I finally figured out what is wrong with udev on ubuntu.

ubuntu mounts usbfs as /proc/bus/usb/.usbfs
and has udev create /dev/bus/usb and bind-mounts that as /proc/bus/usb.

so even though I get events for /proc/bus/usb/NNN/NNN devices and they
exist if I manually look, my app doesn't find them. the reason is: udev runs
/lib/udev/openct_usb, but creates the device in /dev/bus/usb (and thus on
ubuntu /proc/bus/usb) only after my script finishes. while I can add sleeps
to avoid races, they don't help because udev will not create the device until
my script gives up.

the solution is to add some

( ...

) &
disown %1

exit 0

in my script so the core code runs in the background, where it can wait
for the device file to be created by udev and then start the ifdhandler 
process that will handle it.

also during debugging I noticed: it is not a good idea to start/stop udev
using the init script. at first I thought udev wasn't re-reading it rules
properly, so I tried that. but the result of restarting udev init script is
this: /proc/bus/usb is no longer a bind mount of /dev/bus/usb. instead it
is an independend copy, and it is no longer updated at all. thus new devices
show up only in /dev/bus/usb and /proc/bus/usb/.usbfs, but not 
in /proc/bus/usb/.

Regards, Andreas

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