[ovs-dev] Datapath kern log msg key attribute error

[Andy Zhou]

Whenever we instantiate a new ofproto (i.e. bridge), we probe datapath
to detect if it supports MPLS, and if yes, how many labels it can
support.  The probing produces similar error messages on my system.
It should only appear when you add the bridge, but not afterwards.

On Thu, Apr 24, 2014 at 12:27 PM, Thomas F Herbert
<thomasfherbert at gmail.com> wrote:
> On 4/24/2014 1:47 PM, Jesse Gross wrote:
>>
>> On Thu, Apr 24, 2014 at 8:38 AM, Thomas F Herbert
>> <thomasfherbert at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> I think there is a problem with parsing out the OVS ATTRIBUTE nesting in
>>> the
>>> NL message in the datapath and I am having trouble finding the cause. I
>>> think the nl msg is built up wrong in the case of the vlan push action.
>>>
>>> I first saw the problem while testing my patch for 802.1ad. However, I
>>> also
>>> see the same problem WITHOUT the patch on commits in the master branch.
>>>
>>> The message appears in the kern log for commit dcbe78 and subsequent
>>> commits
>>> on the master branch. The message does NOT appear in the 2.1 release
>>> branch.
>>>
>>> Apr 23 07:50:11 lubuntu-12 kernel: [ 1009.493608] openvswitch: netlink:
>>> Key
>>> attribute has unexpected length (type=62, length=4, expected=0).
>>>
>>> Message is from line 300 in datapath/flow_netlink.c
>>>
>>> It is interesting that type 62 is the maximum key attribute value.
>>>
>>> The problem can be also  reproduced with the following command with
>>> commit
>>> f487a:
>>>
>>> ovs-ofctl -vdbg --protocols=OpenFlow11 add-flow br0
>>> in_port=1,actions=push_vlan:0x8100,load:0x64-\>OXM_OF_VLAN_VID[],output:2
>>
>> This attribute is for MPLS, which userspace supports but the kernel
>> doesn't. This shouldn't be generated in any case but is there any MPLS
>> traffic here?
>
> There is no traffic at all when the message appears.
>
>>
>> You could try bisecting since you have points in the code where it is
>> working and not. It might also be worth setting the log level to debug
>> to watch the upcalls and flow installations.
>
> OK, Jesse, I will debug by bisecting the commit history to see where it
> first appeared and get back to you when I find it.
>
> There is no traffic yet and it occurs before any flows are pushed. The
> message appears when the bridge is initially set up with the following
> command.
>
> ovs-vsctl add-br br0
>
>
>
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