[CRIU] [PATCH CRIU 08/14] restore/net/ipv6: net device and def/all configuration

[Pavel Tikhomirov]

On 04/04/2016 06:29 PM, Pavel Tikhomirov wrote:
>
>
> On 04/04/2016 06:03 PM, Pavel Emelyanov wrote:
>> On 04/04/2016 05:46 PM, Pavel Tikhomirov wrote:
>>>
>>>
>>> On 04/04/2016 05:40 PM, Pavel Emelyanov wrote:
>>>> On 04/04/2016 04:58 PM, Pavel Tikhomirov wrote:
>>>>>
>>>>>
>>>>> On 04/04/2016 04:38 PM, Pavel Emelyanov wrote:
>>>>>> On 04/04/2016 01:30 PM, Pavel Tikhomirov wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 04/04/2016 01:16 PM, Pavel Emelyanov wrote:
>>>>>>>>
>>>>>>>>> @@ -163,9 +163,11 @@ static int net_conf_op(char *tgt, int
>>>>>>>>> *conf, int n, int op, char *proto,
>>>>>>>>>                  continue;
>>>>>>>>>              }
>>>>>>>>>              /*
>>>>>>>>> -         * If dev conf value is the same as default skip
>>>>>>>>> restoring it
>>>>>>>>> +         * If dev conf value is the same as default skip
>>>>>>>>> restoring it,
>>>>>>>>> +         * mtu may be changed by disable_ipv6 so we can not skip
>>>>>>>>> +         * it's restore
>>>>>>>>>               */
>>>>>>>>
>>>>>>>> No, this means that we should restore mtu after disable_ipv6.
>>>>>>>> And we still can check
>>>>>>>> for it to match default value.
>>>>>>>
>>>>>>> Imagine situation:
>>>>>>> 1)restore disable_ipv6 for default
>>>>>>> 2)restore mtu for default
>>>>>>> 3)create eth0
>>>>>>> 4)restore disable_ipv6 for eth0
>>>>>>> 5)restore mtu for eth0
>>>>>>>
>>>>>>> After step 3 both default and eth0 mtu are set to default value. But
>>>>>>> after step 4 eth0's one can possibly change. So do you mean we
>>>>>>> need to
>>>>>>> first restore both default/disable_ipv6 and eth0/disable_ipv6 and
>>>>>>> only
>>>>>>> after that restore default/mtu ?
>>>>>>
>>>>>> No. By step 5 will eth0's mtu match the default mtu?
>>>>>
>>>>> By step 5 we will have eth0/mtu(in image) equal to default/mtu(in
>>>>> image)
>>>>> equal to default/mtu(sysctl) but not equal to eth0/mtu(sysctl).
>>>>
>>>> How can this happen? Anything in the image should match the same in
>>>> sysctl-s
>>>> on the dump side, so if eth0.mtu == default.mtu in image, then the
>>>> same is
>>>> true for sysctls on dump side. Why should it differ on restore?
>>>
>>>   From comment to 06/14 patch:
>>>
>>>   >In
>>> addrconf_sysctl_disable->addrconf_disable_ipv6->dev_disable_change:
>>>   >On addrconf_notify + NETDEV_UP if idev->cnf.mtu6 differs from
>>> dev->mtu,
>>>   >sysctl mtu6 is overwritten.
>>>   >
>>>   >So changing disable_ipv6 sysctl for some device may change mtu sysctl
>>>   >for it...
>>>
>>> eth0.mtu sysctl changed on step 4.
>>
>> Argh... Let's come with examples. Would you show the combination of
>> eth0/default
>> mtu/disable_ipv6 -s _in_ _images_ that would be restored wrongly if we
>> don't
>> make the check you suggest?
>

In images:

eth0.mtu = 1500

def_conf6.mtu=1280 def_conf.disable_ipv6=1
eth0.conf6.mtu=1280 eth0.conf6.disable_ipv6=0

> Very sorry, missed _in_ _images_, will do now.
>
>>
>> -- Pavel
>>
>

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.