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

From: Ding Tianhong <[email-masked]>
Date: Thu, 12 Jun 2014 09:45:12 +0800

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.

Thanks
Ding

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