Use the EVENTHANDLER system to hook into the usb device configuration and
perform a function such as ejecting a 3G autoinstaller disk. The eventhandler
system properly tracks threads and is safe to unload, remove the
setting/clearing of a function pointer in the kernel by u3g(4) which included a
tsleep for safety.
Change the roothub exec functions to take the usb request and data pointers
directly rather than placing them on the parent bus struct.
Submitted by: Hans Petter Selasky
