Re: [PATCH] ipv6: don't call addrconf_dst_alloc again when enable lo

[chenweilong <chenweilong@huawei.com>]

On 2014/1/2 14:03, Hannes Frederic Sowa wrote:
> On Thu, Jan 02, 2014 at 01:48:46PM +0800, chenweilong wrote:
>> On 2013/12/31 11:57, Hannes Frederic Sowa wrote:
>>> On Wed, Jun 19, 2013 at 11:05:32PM -0700, David Miller wrote:
>>>> From: Gao feng <gaofeng@cn.fujitsu.com>
>>>> Date: Sun, 16 Jun 2013 11:14:30 +0800
>>>>
>>>>> If we disable all of the net interfaces, and enable
>>>>> un-lo interface before lo interface, we already allocated
>>>>> the addrconf dst in ipv6_add_addr. So we shouldn't allocate
>>>>> it again when we enable lo interface.
>>>>>
>>>>> Otherwise the message below will be triggered.
>>>>> unregister_netdevice: waiting for sit1 to become free. Usage count = 1
>>>>>
>>>>> This problem is introduced by commit 25fb6ca4ed9cad72f14f61629b68dc03c0d9713f
>>>>> "net IPv6 : Fix broken IPv6 routing table after loopback down-up"
>>>>>
>>>>> Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
>>>>
>>>> This is the second such regression added by that commit :-/
>>>>
>>>> Applied and queue up for -stable, thanks.
>>>
>>> Hmm, and this change also has a regression and breaks the original fix. :/
>>>
>>> https://bugzilla.kernel.org/show_bug.cgi?id=67951
>>>
>>> I tried to track it down but it seems pretty complicated. Maybe we have to
>>> special-case the take-down of the loopback device.
>>>
>>>
>>>
>>
>> When I did the tests,If 'ifconfig lo down',all IPv6 connection broken,
>> but IPv4 connection were still OK.
>>
>> Is it designed like that or a bug?
> 
> It is designed this way.
> 
> Greetings,
> 
>   Hannes
> 
> 
> .
> 
Can you give more explanation about this please?

Thanks!