libvirt users - Jul 2012 - INTERNAL ERROR:can not attach network interface for vm

hello,i got a error message when use virsh attach-interface for a vm:

first, list the vm's interface,there's no interface now.
virsh # domiflist ubuntum-124
Interface  Type       Source     Model       MAC
-------------------------------------------------------

then,i did an attach-interface action:
virsh # attach-interface ubuntum-124  bridge br0 --persistent
Interface attached successfully

virsh # domiflist ubuntum-124
Interface  Type       Source     Model       MAC
-------------------------------------------------------
vnet0      bridge     br0        -           52:54:00:3d:d1:ea

second,detach the interface:
virsh # detach-interface ubuntum-124 bridge
Interface detached successfully

virsh # domiflist ubuntum-124
Interface  Type       Source     Model       MAC
-------------------------------------------------------

3rd,attach interface again,at this step ,i got erros like below:
virsh # attach-interface ubuntum-124  bridge br0 --persistent
error: Failed to attach interface
error: internal error unable to execute QEMU command 'device_add':
Duplicate ID 'net0' for device

virsh # attach-interface ubuntum-124  bridge br0
error: Failed to attach interface
error: internal error unable to execute QEMU command 'device_add':
Duplicate ID 'net0' for device

virsh # version
Compiled against library: libvir 0.9.10
Using library: libvir 0.9.10
Using API: QEMU 0.9.10
Running hypervisor: QEMU 0.12.1

any one can help?thanks.

On 2012?07?23? 17:24, Gao Yongwei wrote:
> hello,i got a error message when use virsh attach-interface for a vm:
>
> first, list the vm's interface,there's no interface now.
> virsh # domiflist ubuntum-124
> Interface  Type       Source     Model       MAC
> -------------------------------------------------------
>
> then,i did an attach-interface action:
> virsh # attach-interface ubuntum-124  bridge br0 --persistent
> Interface attached successfully
>
> virsh # domiflist ubuntum-124
> Interface  Type       Source     Model       MAC
> -------------------------------------------------------
> vnet0      bridge     br0        -           52:54:00:3d:d1:ea
>
> second,detach the interface:
> virsh # detach-interface ubuntum-124 bridge
> Interface detached successfully
>
> virsh # domiflist ubuntum-124
> Interface  Type       Source     Model       MAC
> -------------------------------------------------------
>
> 3rd,attach interface again,at this step ,i got erros like below:
> virsh # attach-interface ubuntum-124  bridge br0 --persistent
> error: Failed to attach interface
> error: internal error unable to execute QEMU command 'device_add':
> Duplicate ID 'net0' for device
>
> virsh # attach-interface ubuntum-124  bridge br0
> error: Failed to attach interface
> error: internal error unable to execute QEMU command 'device_add':
> Duplicate ID 'net0' for device
>
> virsh # version
> Compiled against library: libvir 0.9.10
> Using library: libvir 0.9.10
> Using API: QEMU 0.9.10
> Running hypervisor: QEMU 0.12.1
>
It's known bug of qemu, there is some race there, though I can't
tell what it is exactly. I guess if you sleep several secs
before attaching it again, you will succeed. Or you might want to
ask in qemu list.

Regards,
Osier