[libvirt] [PATCH v3 06/36] util: add helper method for re-attaching a tap device to a bridge

Laine Stump laine at laine.org
Fri Mar 22 02:21:25 UTC 2019


On 3/21/19 9:14 PM, Cole Robinson wrote:
> On 3/19/19 8:46 AM, Daniel P. Berrangé wrote:
>> Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
>> ---
>>   src/libvirt_private.syms |  1 +
>>   src/util/virnetdevtap.c  | 69 ++++++++++++++++++++++++++++++++++++++++
>>   src/util/virnetdevtap.h  | 12 +++++++
>>   3 files changed, 82 insertions(+)
>>
>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>> index d9494a04bb..6f5a734fdb 100644
>> --- a/src/libvirt_private.syms
>> +++ b/src/libvirt_private.syms
>> @@ -2461,6 +2461,7 @@ virNetDevTapDelete;
>>   virNetDevTapGetName;
>>   virNetDevTapGetRealDeviceName;
>>   virNetDevTapInterfaceStats;
>> +virNetDevTapReattachBridge;
>>   
>>   
>>   # util/virnetdevveth.h
>> diff --git a/src/util/virnetdevtap.c b/src/util/virnetdevtap.c
>> index 972f3405aa..0484c7c5a4 100644
>> --- a/src/util/virnetdevtap.c
>> +++ b/src/util/virnetdevtap.c
>> @@ -553,6 +553,75 @@ virNetDevTapAttachBridge(const char *tapname,
>>   }
>>   
>>   
>> +/**
>> + * virNetDevTapReattachBridge:
>> + * @tapname: the tap interface name (or name template)
>> + * @brname: the bridge name
>> + * @macaddr: desired MAC address
>> + * @virtPortProfile: bridge/port specific configuration
>> + * @virtVlan: vlan tag info
>> + * @mtu: requested MTU for port (or 0 for "default")
>> + * @actualMTU: MTU actually set for port (after accounting for bridge's MTU)
>> + *
>> + * Ensures that the tap device (@tapname) is connected to the bridge
>> + * (@brname), potentially removing it from any existing bridge that
>> + * does not match.
>> + *
>> + * Returns 0 in case of success or -1 on failure
>> + */
>> +int
>> +virNetDevTapReattachBridge(const char *tapname,
>> +                           const char *brname,
>> +                           const virMacAddr *macaddr,
>> +                           const unsigned char *vmuuid,
>> +                           virNetDevVPortProfilePtr virtPortProfile,
>> +                           virNetDevVlanPtr virtVlan,
>> +                           unsigned int mtu,
>> +                           unsigned int *actualMTU)
>> +{
>> +    bool useOVS = false;
>> +    char *master = NULL;
>> +
> Could use VIR_AUTOFREE to simplify things a bit
>
>> +    if (virNetDevGetMaster(tapname, &master) < 0)
>> +        return -1;
>> +
>> +    /* IFLA_MASTER for a tap on an OVS switch is always "ovs-system" */
>> +    if (STREQ_NULLABLE(master, "ovs-system")) {
>> +        useOVS = true;
>> +        VIR_FREE(master);
>> +        if (virNetDevOpenvswitchInterfaceGetMaster(tapname, &master) < 0)
>> +            return -1;
>> +    }
>> +
>> +    /* Nothing more todo if we're on the right bridge already */
>> +    if (STREQ_NULLABLE(brname, master))
>> +        return 0;
>> +
>> +    /* disconnect from current (incorrect) bridge, if any  */
>> +    if (master) {
>> +        int ret;
>> +        VIR_INFO("Removing %s from %s", tapname, master);
>> +        if (useOVS)
>> +            ret = virNetDevOpenvswitchRemovePort(master, tapname);
>> +        else
>> +            ret = virNetDevBridgeRemovePort(master, tapname);
>> +        VIR_FREE(master);
>> +        if (ret < 0)
>> +            return -1;
>> +    }
>> +
> These were non-fatal in the original code. Is it okay to change?


I don't remember why I made those non-fatal in the original code. 
Probably wanted to give as high a chance as possible of muddling through 
even in the face of errors from ovs. But looking at the code again, I 
agree that it's just as well to fail hard instead of ignoring the errors.


>
> Provided there's an answer:
>
> Reviewed-by: Cole Robinson <crobinso at redhat.com>
>
> - Cole
>
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list





More information about the libvir-list mailing list