panic when unplugging USB keyboard/hub/mouse

[Timo Buhrmester <fstd.lkml%gmail.com@localhost>]

Hi list,

I'm running into this panic when "unplugging" [pressing the toggle button on an USB KVM-ish switch] an USB hub.
> panic: kernel diagnostic assertion "xfer->ux_state == XFER_ONQU" failed: file "/usr/src/sys/dev/usb/usbdi.c", line 906

My setup for controlling two computers with one set of keyboard/mouse looks like this:

|        +---------+       +--------+                                                                                                                         
| PC1----|         |       |Keyboard|
|        |USB "KVM"|-------|  with  |      +-----+                                                                                                                                 
| PC2----|         |       |USB Hub |------|Mouse|                                                                                                                                          
|        +---------+       +--------+      +-----+                                                                                                              

The KVM has a button to toggle between PC1 and PC2.  When the mouse is *not* connected,
things work fine.  However when the mouse *is* connected, more often than not I'll get
the above panic when moving control away from the NetBSD machine.  This leads me to assume
that the problem is with removing a hub that has active devices.

This is not a new problem, my current workaround is to pull the mouse, then press the
KVM button, then connect the mouse again, but I'm getting tired of it.

I'll follow up with a backtrace the next time it happens.