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

[Pavel Tikhomirov]

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.

>
> -- Pavel
>

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