When unplugging a device in the Xen pvusb backend drain the submit
queue before deallocation of the control structures. Otherwise there
will be bogus memory accesses when I/O contracts are finished.
Correlated to this issue is the handling of cancel requests: a packet
cancelled will still lead to the call of complete, so add a flag
to the request indicating it should be just dropped on complete.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Bruce Rogers <brogers@suse.com>