On Wed, Jan 25, 2012 at 04:09:22PM +0100, Hendrik Schwartke wrote:
> I wrote a patch to change the mapping between a virtual bridge
> interface and the host bridge while the host is up. It's based on
> commit 6fba577e505611e6c25c68e322942eab7754de7e. The host and the
> interface definition I used for testing are also attached.
> I would be glad if the patch could be added to the repo.
Great !
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 4b60839..f791795 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -40,6 +40,7 @@
> #include "qemu_cgroup.h"
> #include "locking/domain_lock.h"
> #include "network/bridge_driver.h"
> +#include "util/virnetdevbridge.h"
>
> #define VIR_FROM_THIS VIR_FROM_QEMU
>
> @@ -1163,6 +1164,28 @@ static virDomainNetDefPtr
> qemuDomainFindNet(virDomainObjPtr vm,
> return NULL;
> }
>
> +int qemuDomainChangeNetBridge(virDomainNetDefPtr olddev,
> + virDomainNetDefPtr newdev)
> +{
> + const char *oldbridge=olddev->data.bridge.brname;
> + const char *newbridge=newdev->data.bridge.brname;
> + VIR_DEBUG("Change bridge for interface %s: %s -> %s",
> olddev->ifname, oldbridge, newbridge);
> + if(virNetDevBridgeRemovePort(oldbridge, olddev->ifname)<0) {
> + qemuReportError(VIR_ERR_OPERATION_FAILED,
> + _("unable to remove port from bridge"));
Good idea to include the bridge device name too
> + return -1;
> + }
> + if(virNetDevBridgeAddPort(newbridge, newdev->ifname)<0) {
> + qemuReportError(VIR_ERR_OPERATION_FAILED,
> + _("unable to add port to bridge"));
> + return -1;
> + }
Hmm, we'd end up with no NIC backend command at all here.
So we'd probably want to move the VIR_FREE() line before
here, so if we fail half-way through, we still update
the XML. To avoid stupid mistakes we also probably want
to check for existance of the target bridge before unplugging
fromthe source
> + VIR_FREE(olddev->data.bridge.brname);
> + olddev->data.bridge.brname=strdup(newbridge);
We could just steal newbridge from the newdev and
avoid the OOM potential
> + return 0;
> +}
Various whitespace fixes
- For assignment, we prefer 'foo = bar' instead of 'foo=bar'
- For conditionals 'if (' instead of 'if('
- For tests "foo < 0" instead of "foo<0"
So all in all I think I'd write this as
int qemuDomainChangeNetBridge(virDomainNetDefPtr olddev,
virDomainNetDefPtr newdev)
{
const char *oldbridge = olddev->data.bridge.brname;
const char *newbridge = newdev->data.bridge.brname;
VIR_DEBUG("Change bridge for interface %s: %s -> %s",
olddev->ifname, oldbridge, newbridge);
if (!virNetDevExists(newbridge)) {
qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
_("unable to remove port from bridge"));
return -1;
}
if (oldbridge &&
virNetDevBridgeRemovePort(oldbridge, olddev->ifname) < 0) {
qemuReportError(VIR_ERR_OPERATION_FAILED,
_("unable to remove port from bridge %s"), oldbridge);
return -1;
}
VIR_FREE(olddev->data.bridge.brname);
if (virNetDevBridgeAddPort(newbridge, newdev->ifname) < 0) {
qemuReportError(VIR_ERR_OPERATION_FAILED,
_("unable to add port to bridge"), newbridge);
return -1;
}
olddev->data.bridge.brname = newdev->data.bridge.brname;
newdev->data.bridge.brname = NULL;
return 0;
}
> +
> int qemuDomainChangeNetLinkState(struct qemud_driver *driver,
> virDomainObjPtr vm,
> virDomainNetDefPtr dev,
> @@ -1293,6 +1316,12 @@ int qemuDomainChangeNet(struct qemud_driver *driver,
> return -1;
> }
>
> + if(olddev->type==VIR_DOMAIN_NET_TYPE_BRIDGE
> + && dev->type==VIR_DOMAIN_NET_TYPE_BRIDGE
> + && STRNEQ(olddev->data.bridge.brname, dev->data.bridge.brname)) {
> + qemuDomainChangeNetBridge(olddev, dev);
> + }
And use STRNEQ_NULLABLE here to avoid risk of NULL brname field,
and if qemuDomainChangeNetBridge() returns -1, we need to return
to the caller here.
> +
> if (olddev->linkstate != dev->linkstate) {
> if ((ret = qemuDomainChangeNetLinkState(driver, vm, olddev,
> dev->linkstate)) < 0)
> return ret;
> diff --git a/src/qemu/qemu_hotplug.h b/src/qemu/qemu_hotplug.h
> index 0310361..1e1f75c 100644
> --- a/src/qemu/qemu_hotplug.h
> +++ b/src/qemu/qemu_hotplug.h
> @@ -80,6 +80,8 @@ int qemuDomainChangeNetLinkState(struct
> qemud_driver *driver,
> virDomainObjPtr vm,
> virDomainNetDefPtr dev,
> int linkstate);
> +int qemuDomainChangeNetBridge(virDomainNetDefPtr olddev,
> + virDomainNetDefPtr newdev);
> int qemuDomainDetachPciDiskDevice(struct qemud_driver *driver,
> virDomainObjPtr vm,
> virDomainDeviceDefPtr dev);
>
>
> Host definition:
> <domain type='kvm'>
> <name>test</name>
> <memory>32768</memory>
> <currentMemory>32768</currentMemory>
> <vcpu>1</vcpu>
> <os>
> <type arch='x86_64' machine='pc-0.12'>hvm</type>
> <boot dev='cdrom'/>
> <bootmenu enable='no'/>
> </os>
> <features>
> <acpi/>
> <apic/>
> <pae/>
> </features>
> <clock offset='utc'/>
> <on_poweroff>destroy</on_poweroff>
> <on_reboot>restart</on_reboot>
> <on_crash>restart</on_crash>
> <devices>
> <emulator>/usr/bin/kvm</emulator>
> <controller type='ide' index='0'>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
> </controller>
> <interface type='bridge'>
> <mac address='52:54:00:ab:cd:02'/>
> <source bridge='br0'/>
> <target dev='testif'/>
> <link state='up'/>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
> </interface>
> <serial type='pty'>
> <target port='0'/>
> </serial>
> <console type='pty'>
> <target type='serial' port='0'/>
> </console>
> <input type='tablet' bus='usb'/>
> <input type='mouse' bus='ps2'/>
> <graphics type='vnc' port='-1' autoport='yes'/>
> <video>
> <model type='cirrus' vram='9216' heads='1'/>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
> </video>
> <memballoon model='virtio'>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
> </memballoon>
> </devices>
> </domain>
>
>
> Interface definition:
> <interface type="bridge">
> <mac address="52:54:00:ab:cd:02"/>
> <source bridge="br1"/>
> <target dev="testif"/>
> <link state="up"/>
> <alias name="net0"/>
> <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0"/>
> </interface>
>
>
>
> Best regards
> Hendrik Schwartke
>
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