notify userspace of offline -> running transitions

http://marc.info/?l=linux-scsi&m=133769378525796&w=2

Did anything ever happen with this? I don't see that it did.

There seems to be a problem with udev processing an event for a device at a time when the device can't be accessed. Mike's original fix was to generate another KOBJ_CHANGE event when the device comes back online, so that subsequent udev rule processing would succeed. Even so, the device could become inaccessible again by the time the event was actually processed by udev (if udevd was overloaded...)

-Ewan