[libvirt] device removal

[Serge Hallyn]

Hi,

one of our tests was complaining that after an attach-device
followed by detach-device, the device was still in the vm's
apparmor whitelist.  It turns out the device actually also
still in the device's xml.  qemuDomainDetachVirtioDiskDevice()
is calling

    if (!qemuDomainWaitForDeviceRemoval(vm))
        qemuDomainRemoveDiskDevice(driver, vm, detach);
    ret = 0;

Return values for qemuDomainWaitForDeviceRemoval are:

 *  -1 on error
 *   0 when DEVICE_DELETED event is unsupported
 *   1 when device removal finished
 *   2 device removal did not finish in QEMU_REMOVAL_WAIT_TIME

Those don't seem in line with how the return value is used.  (According
to gdb, it is returning 2 in my case.) I don't understand how the async
device removal proceeds, but if qemuDomainWaitForDeviceRemoval()
returned an error (-1 or 2) should qemuDomainDetachVirtioDiskDevice() at
least return an error, assuming it's not safe to call
qemuDomainRemoveDiskDevice()?

As it is, I get

# serge at t1:~/qa-regression-testing/scripts$ virsh detach-device qatest-i386 /tmp/tmpivE45x/device.xml
# Device detached successfully

but the device is actually still in qatest-i386's xml.  Seems like the
caller should be informed that the device is still attached.  Assuming
I'm not completely mis-reading the situation.

thanks,
-serge