[CRIU] [PATCH CRIU 04/14] dump/net/ipv4: add unused bitmask to allow negative sysctl values

[Pavel Tikhomirov]

On 04/04/2016 04:36 PM, Pavel Emelyanov wrote:
> On 04/04/2016 01:21 PM, Pavel Tikhomirov wrote:
>>
>>
>> On 04/04/2016 01:14 PM, Pavel Emelyanov wrote:
>>> On 03/30/2016 01:42 PM, Pavel Tikhomirov wrote:
>>>> Some sysctls can be set with value < 0: ipv4/conf//accept_source_route,
>>>> ipv4/conf//medium_id, ipv4/conf//tag, ipv6/conf//accept_source_route,
>>>> ipv6/conf//keep_addr_on_down. So we can not use -1 as unused value.
>>>
>>> I don't get the problem we fix with this patch. Why not just saving whatever
>>> value we have instead of marking it with a special bit?
>>
>> The problem is on old kernels we might not have all sysctls, so we need
>> somehow mark those to not to fail on them on restore. Before these
>> patch, we marked unused sysctls with -1, and did not restore it. But
>> what if some sysctl is really set to -1?
>
> OK, so how old is the "old kernel"? And what sysctls are we talking about --
> some that are already in CRIU, or the ones that you add with this set?

For ipv4 only in kernels 4.2+:
ignore_routes_with_linkdown - in criu since v1.8
drop_gratuitous_arp - new
drop_unicast_in_l2_multicast - new

For ipv6 don't have on my node(Fedora 20, kernel 3.19.8-100.fc20.x86_64):
accept_ra_min_hop_limit
accept_ra_mtu
drop_unicast_in_l2_multicast
drop_unsolicited_na
ignore_routes_with_linkdown
keep_addr_on_down
use_oif_addrs_only

>

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