[libvirt] [PATCH] qemu: don't fail update netdev on bridge detach failure

When a network device's bridge connection is changed by virDomainUpdateDevice, libvirt first removes the netdev's tap from its old bridge, then adds it to the new bridge. Sometimes, due to a network being destroyed while a guest device is still attached, the tap may already be "removed" from the old bridge (or the old bridge may not even exist any more); the existing code was needlessly failing the update when this happened, making it impossible to recover from the situation without completely detaching (i.e. removing) the netdev from the guest and re-attaching. Instead of failing the entire operation when removal of the tap from the old bridge fails, this patch changes qemuDomainChangeNetBridge to just log a warning and continue, allowing a reasonable recover from the situation. (you'll appreciate this change if you ever accidentally destroy a network while your guests are still using it). --- src/qemu/qemu_hotplug.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c index 3dfdb65..e9a5e35 100644 --- a/src/qemu/qemu_hotplug.c +++ b/src/qemu/qemu_hotplug.c @@ -1306,8 +1306,14 @@ qemuDomainChangeNetBridge(virConnectPtr conn, if (oldbridge) { ret = virNetDevBridgeRemovePort(oldbridge, olddev->ifname); virDomainAuditNet(vm, olddev, NULL, "detach", ret == 0); - if (ret < 0) - goto cleanup; + if (ret < 0) { + /* warn but continue - possibly the old network + * had been destroyed and reconstructed, leaving the + * tap device orphaned. + */ + VIR_WARN("Unable to detach device %s from bridge %s", + olddev->ifname, oldbridge); + } } ret = virNetDevBridgeAddPort(newbridge, olddev->ifname); -- 1.7.11.7