On 11/02/2010 11:47 AM, Daniel P. Berrange wrote:
On Tue, Nov 02, 2010 at 11:35:44AM -0400, Stefan Berger wrote:
During a shutdown/restart cycle libvirtd forgot the macvtap device name that it had created on behalf of a VM so that a stale macvtap device remained on the host when the VM terminated. Libvirtd has to actively tear down a macvtap device and it uses its name for identifying which device to tear down.
The solution is to not blank out the<target dev='...'/> completely, but only blank it out on VMs that are not active. So, if a VM is active, the device name makes it into the XML and is also being parsed. If a VM is not active, the device name is discarded.
Signed-off-by: Stefan Berger<stefanb@us.ibm.com>
--- src/conf/domain_conf.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
Index: libvirt-acl/src/conf/domain_conf.c =================================================================== --- libvirt-acl.orig/src/conf/domain_conf.c +++ libvirt-acl/src/conf/domain_conf.c @@ -2343,7 +2343,8 @@ virDomainNetDefParseXML(virCapsPtr caps, def->data.direct.linkdev = dev; dev = NULL;
- VIR_FREE(ifname); + if ((flags& VIR_DOMAIN_XML_INACTIVE)) + VIR_FREE(ifname); The conditional isn't required here - it is already dealt with earlier on in the file. Just remove the VIR_FREE completely.
The conditional further above is this code fragment here: } else if ((ifname == NULL) && xmlStrEqual(cur->name, BAD_CAST "target")) { ifname = virXMLPropString(cur, "dev"); if ((ifname != NULL) && ((flags & VIR_DOMAIN_XML_INACTIVE) && (STRPREFIX((const char*)ifname, "vnet")))) { /* An auto-generated target name, blank it out */ VIR_FREE(ifname); } Unfortunately it is also testing for the prefix 'vnet'. In case of a macvtap device I don't want to pick up the name of the macvtap device from the XML unless it's attached to a running domain. So that's why I remove it above. If the domain went down without libvirt 'seeing' it then we miessed out on tearing it down and in that case there may be a stale device, but I don't support this case. So I also want to have that cleared. Further, I also don't accept user-provided interface names for the reason of tear-down in case of failures while trying to start a VM. In the failure-case it is not clear anymore whether the name was user-provided and was previously created and needs to be torn down or simply is a user-provided name of an interface that wasn't created and thus should not be torn down because it may actually be clashing with the user-provided name of a running VM. I had that before and this ended up running danger of tearing down interfaces of running VMs when a failure-path was invoked. So, in case a ifname is given in case of macvtap (type 'direct') it means it was started before and needs to be torn down. After every tear-down the ifname is also free()d.
@@ -5801,6 +5802,8 @@ virDomainNetDefFormat(virBufferPtr buf, virBufferAddLit(buf, "/>\n"); virVirtualPortProfileFormat(buf, &def->data.direct.virtPortProfile, " "); + if ((flags& VIR_DOMAIN_XML_INACTIVE)) + VIR_FREE(def->ifname); This seems dubious. Formatting XML should never require changing 'def' at all.
Let me remove it and test it only with the modification above kept as-is. Stefan
Daniel.