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From: Wen Congyang <wency@cn.fujitsu.com>
Message-ID: <563B2278.6090609@cn.fujitsu.com>
Date: Thu, 5 Nov 2015 17:33:44 +0800
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Subject: Re: [Qemu-devel] [PATCH COLO-Frame v10 35/38] netfilter: Introduce
 a API to automatically add filter-buffer for each netdev
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To: Jason Wang <jasowang@redhat.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>, qemu-devel@nongnu.org
Cc: lizhijian@cn.fujitsu.com, quintela@redhat.com, yunhong.jiang@intel.com, eddie.dong@intel.com, dgilbert@redhat.com, peter.huangpeng@huawei.com, arei.gonglei@huawei.com, stefanha@redhat.com, amit.shah@redhat.com

On 11/05/2015 05:21 PM, Jason Wang wrote:
> 
> 
> On 11/05/2015 04:52 PM, Wen Congyang wrote:
>> On 11/05/2015 03:43 PM, zhanghailiang wrote:
>>>> Hi Jason,
>>>>
>>>> On 2015/11/4 10:56, Jason Wang wrote:
>>>>>>
>>>>>>
>>>>>> On 11/03/2015 07:56 PM, zhanghailiang wrote:
>>>>>>>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>>>>>>>> Cc: Jason Wang <jasowang@redhat.com>
>>>>>>
>>>>>> Commit log please.
>>>>>>
>>>>>>>> ---
>>>>>>>> v10: new patch
>>>>>>>> ---
> 
> [...]
> 
>>>>>>>> +}
>>>>>>>> +/*
>>>>>>>> +* This will be used by COLO or MC FT, for which they will need
>>>>>>>> +* to buffer all the packets of all VM's net devices, Here we check
>>>>>>>> +* and automatically add netfilter for netdev that doesn't attach any buffer
>>>>>>>> +* netfilter.
>>>>>>>> +*/
>>>>>>>> +void qemu_auto_add_filter_buffer(NetFilterDirection direction, Error **errp)
>>>>>>>> +{
>>>>>>>> +    char *queue = g_strdup(NetFilterDirection_lookup[direction]);
>>>>>>>> +
>>>>>>>> +    qemu_foreach_netdev(netdev_add_filter_buffer, queue,
>>>>>>>> +                                        errp);
>>>>>>>> +    g_free(queue);
>>>>>>>> +}
>>>>>>>> +
>>>>>>
>>>>>> This make me think for following questions:
>>>>>>
>>>>>> - What if a nic is hot added after this "automatically" filter add?
>> IIRC, we don't allow the user to hotplug a device when colo is running.
>>
>> Thanks
>> Wen Congyang
>>
> 
> Even in the future? And how could forbid the user to do this, management?

If we allow the user to hotplug a device, we need to auto hotplug the same device
in the secondary qemu. It is hard to implement it now.

We can add a new flag(for example: MONITOR_CMD_COLO_UNSUPPORTED), and do the check
in handle_user_command() and handle_qmp_command().

Thanks
Wen Congyang

> 
> Thanks
> .
>