Re: [PATCH net RESEND] vlan: don't allow to add VLAN on VLAN device

[Ding Tianhong]

On 2014/2/28 13:41, Florian Fainelli wrote:
> 2014-02-27 21:26 GMT-08:00 Ding Tianhong <dingtianhong@xxxxxxxxxx>:
>> On 2014/2/28 11:45, John Fastabend wrote:
>>> On 2/27/2014 6:43 PM, Ding Tianhong wrote:
>>>> I run these steps:
>>>>
>>>> modprobe 8021q
>>>> vconfig add eth2 20
>>>> vconfig add eth2.20 20
>>>> ifconfig eth2 xx.xx.xx.xx
>>>>
>>>> then the Call Trace happened:
>>>>
>>>
>>> [...]
>>>
>>>> ========================================================================
>>>>
>>>> The reason is that if add vlan on vlan dev, the vlan dev will create vlan_info,
>>>> then the notification will let the real dev to run dev_set_rx_mode() and hold
>>>> netif_addr_lock, and then the real dev will call ndo_set_rx_mode(), if the real
>>>> dev is vlan dev, the ndo_set_rx_mode() will hold netif_addr_lock again, so deadlock
>>>> happened.
>>>>
>>>> Don't allow to add vlan on vlan dev to fix this problem.
>>>>
>>>> Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
>>>> ---
>>>
>>> I'm not sure we can just disable stacked vlans. There might be something
>>> using them today and they have worked in the past. Lets try to find a
>>> better fix.
>>>
>>> .John
>>
>> Yes, maybe I miss something, can you gave me a scene that the use of eth2.20.30?
>> the device is created from vlan device eth2.20, than I will find a better way to fix it.
> 
> Is not QinQ (802.1ad) such as case [1]?
> 
> [1]: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8ad227ff89a7e6f05d07cd0acfd95ed3a24450ca
> --
> Florian
> 
> 
Yep, thanks a lot.

Ding

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