Re: [libvirt] RFC: Detaching interface from guest fails with improper error message if no mac given in xml

On 09/29/2017 01:27 PM, Peter Krempa wrote: > On Fri, Sep 29, 2017 at 12:45:30 +0530, Madhu Pavan wrote: > > This RFC is regarding https://bugzilla.redhat.com/show_bug.cgi?id=1497054 > > > > Let's say we have a network interface > >     <interface type='network'> > >       <mac address='52:54:00:fe:10:57'/> > >       <source network='vfnetwork'/> > >       <model type='virtio'/> > >       <address type='pci' domain='0x0000' bus='0x01' slot='0x01' > > function='0x0'/> > >     </interface> > > > > and we are trying to detach the above interface with the following > > xml(vfpool.xml): > >     <interface type='network'> > >       <source network='vfnetwork'/> > >       <model type='virtio'/> > >       <address type='pci' domain='0x0000' bus='0x01' slot='0x01' > > function='0x0'/> > >     </interface> > > Detaching the interface returns error: > > # virsh detach-device vffuest vfpool.xml > > error: Failed to detach device from vfpool.xml > > error: operation failed: no device matching mac address 52:54:00:54:f6:61 > > found > > > > Here the mac address is auto-generated as we haven't given in the > > vfpool.xml. > > And virDomainNetFindIdx will try to match the auto-generated mac address > > with > > the domain xml. It fails as there will be no match and the error message > > says > > "no device matching mac address 52:54:00:54:f6:61 found". > > > > Here in this scenario I see two possible improvements. > > 1. As virDomainNetFindIdx search according to mac address and guest side > >    PCI address (if specified), we can search for PCI address and avoid > >    mac address search if mac is not given in the xml. As the PCI address > >    is unique we don't compromise in performance. > > 2. Improve error message by saying mac address is missing in the device xml. > I think the problem is that the mac address is always generated in the > device XML parser. Auto assignment of the mac address is necessary when > the device is added to the VM. When removing, generating the mac address > is bogus. > > I think we need to make sure that no unique ids are added to the parser > at least in the cases when the XML is parsed for the unplug code path. I have a patch ready to search according to PCI address in the absence of mac address. I can make changes to it so that mac address is not auto-generated. Is this good to proceed in this direction?