Subject: Re: [PATCH net-next v2 RESEND 1/4] macvlan: support mac address changes when fwd_priv is enable

From: Vlad Yasevich <[email-masked]>
Date: Thu, 12 Jun 2014 10:24:55 -0400

On 06/11/2014 09:45 PM, Ding Tianhong wrote:
> On 2014/6/10 0:51, Vlad Yasevich wrote:
>> [.. CC John Fastabend <[email-masked]> ]
>>
>> On 06/07/2014 03:45 AM, Ding Tianhong wrote:
>>> If lowerdev supports L2 forwarding offload, the macvlan's hw address
>>> will be set to the rar of the lowerdev and no need to set uc list,
>>> and when the macvlan's hw address changes, the macvlan should remove
>>> the old fwd and rebuild a new fwd for the macvlan.
>>>
>>> Signed-off-by: Ding Tianhong <[email-masked]>
>>> ---
>>>  drivers/net/macvlan.c | 21 +++++++++++++++++++++
>>>  1 file changed, 21 insertions(+)
>>>
>>> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
>>> index 453d55a..67485ab 100644
>>> --- a/drivers/net/macvlan.c
>>> +++ b/drivers/net/macvlan.c
>>> @@ -523,6 +523,27 @@ static int macvlan_sync_address(struct net_device *dev, unsigned char *addr)
>>>  		if (macvlan_addr_busy(vlan->port, addr))
>>>  			return -EBUSY;
>>>  
>>> +		if (vlan->fwd_priv) {
>>> +			lowerdev->netdev_ops->ndo_dfwd_del_station(lowerdev,
>>> +								   vlan->fwd_priv);
>>> +			vlan->fwd_priv = NULL;
>>> +			ether_addr_copy(dev->perm_addr, dev->dev_addr);
>>> +			ether_addr_copy(dev->dev_addr, addr);
>>> +			vlan->fwd_priv =
>>> +			    lowerdev->netdev_ops->ndo_dfwd_add_station(lowerdev,
>>> +								       dev);
>>> +			/* If we get a NULL pointer back, or if we get an error
>>> +			 * then we should restore the old mac address and fwd.
>>> +			 */
>>> +			if (IS_ERR_OR_NULL(vlan->fwd_priv)) {
>>> +				ether_addr_copy(dev->dev_addr, dev->perm_addr);
>>> +				vlan->fwd_priv =
>>> +				    lowerdev->netdev_ops->ndo_dfwd_add_station(lowerdev,
>>> +									       dev);
>>> +				return -EINVAL;
>>> +			}
>>> +			return 0;
>>> +		}
>>
>> Calling del_stations add_station causes all sorts of VMDQ/ring
>> operations to happen...  Not sure if we can do that while we have a live
>> macvlan/macvtap that is capable of transmitting data.
>>
>> Wouldn't it be sufficient to have a call to call to update with mac
>> filter with the appropriate VMDQ.
>>
>> John, I defer to you here.  The above looks really heavy-weight and
>> I am not sure if its correct.
>>
>> Thanks
>> -vlad
> 
> I have used two 82599 nic to test this problem, I modify the ixgbe drivers and set the  L2 forwarding offload default,
> without this patch, when I change the macvlan mac address, the kernel oops, and if I apply this patch, the ixgbe could
> work well with the maclvan, so I don't think this solution has problem.

Have you tried changing the address while at the same time
transmitting data through the macvlan?

-vlad

> 
> Thanks
> Ding
> 
>>
>>>  		if (!vlan->port->passthru) {
>>>  			err = dev_uc_add(lowerdev, addr);
>>>  			if (err)
>>>
>>
>>
>> .
>>
> 
>