[LTP] [PATCH] network/mpls: sleep 1 after setup in mpls02

[suy.fnst@fujitsu.com]

Hi, Alexey
  Thanks! It works! Could you send a patch for the fix?
  You can add my
  Tested-by: Su Yue <suy.fnst@fujitsu.com>


--
Su

________________________________________
From: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
Sent: Friday, September 10, 2021 16:39
To: pvorel; Su, Yue/苏 越
Cc: ltp@lists.linux.it
Subject: Re: [LTP] [PATCH] network/mpls: sleep 1 after setup in mpls02

On 09.09.2021 18:53, pvorel wrote:
> Hi Su, Alexey,
>
> On 2021-08-30 11:26, suy.fnst@fujitsu.com wrote:
>> Hi,
>>   I found that it's indeed related to ipv6 DAD as you said.
>> Calling
>> `ip netns exec ltp_ns sysctl -n net.ipv6.conf.ltp_ns_veth1.accept_dad=0`
>> or tst_wait_ipv6_dad() at end of the setup both solves the problem.
>> However there is one super strange part that the tentative address is
>> the local link adress of the ltp_ns_veth1:
>>
>> 5: ltp_ns_veth1@if4: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
>> state UP group default qlen 1000
>>     link/ether f2:8f:24:d4:ba:26 brd ff:ff:ff:ff:ff:ff link-netnsid 0
>>     inet 10.0.0.1/24 scope global ltp_ns_veth1
>>        valid_lft forever preferred_lft forever
>>     inet6 fd00:1:1:1::1/64 scope global nodad
>>        valid_lft forever preferred_lft forever
>>     inet6 fe80::f08f:24ff:fed4:ba26/64 scope link tentative
>> <-------------------
>>        valid_lft forever preferred_lft forever
>>
>> However, there is no place using the address in mpls02 test.>> It makes me wonder how could it be possible to trigger the issue..

Looks like the problem here in the neighbor discovery of fd00:1:1:1::2
using link-local address, and vice verse for the other side. mpls is
using the following route with the address:

fd00:23::2  encap mpls  60 via fd00:1:1:1::2 dev ltp_ns_veth1 metric 1024 pref medium
so the address there should be in a reachable state...

Adding it manually in setup might fix the test as well:

ROD ip neigh replace $(tst_ipaddr rhost) lladdr $(tst_hwaddr rhost) dev $(tst_iface) nud reachable
tst_rhost_run -s -c "ip neigh replace $(tst_ipaddr) lladdr $(tst_hwaddr) dev $(tst_iface rhost) nud reachable"

>
> I wonder if test still needs be fixed to work on all setups.
>

I think we could set accept_dad to 0 in generic setup of the
test interfaces, in tst_net.sh/tst_init_iface().