[PATCH] USB: fix uhci "host controller process error"

[PATCH] USB: fix uhci "host controller process error"

By the way, let me explain what the problem was with uhci-hcd.  The usb
hardware directly accesses your computers memory.  The bug is that it
could still be accessing a bit of memory after uhci-hcd thought it had
finished with it and freed up the memory.  This bug has always existed,
and I guess led to occasional mysterious data corruption, when some
other part of the kernel started using that bit of memory while the usb
hardware was still playing with it.  You turned on the "slab debugging"
option, right?  With this turned on, when uhci-hcd frees the memory it
gets filled with some garbage values.  The usb hardware reads this
garbage and barfs, giving a "process error".  In short, you can also
get rid of the process error messages by turning off slab debugging,
then the data corruption will be silent again!