[LTP] [PATCH] netns/netns_helper.sh: Fix failure when testing ipv6 in netns

[Alexey Kodanev]

On 12/15/2017 04:13 PM, Xiao Yang wrote:
> When testing ipv6 in network namespace, we got the following
> error on some distros(e.g. RHEL7.5Alpha):
> ----------------------------------------------------------------------------------
> connect: Cannot assign requested address
> netns_comm_ns_exec_ipv6_netlink 1 TFAIL: configuration and communication over veth0
> connect: Cannot assign requested address
> netns_comm_ns_exec_ipv6_netlink 2 TFAIL: configuration and communication over veth1
> -----------------------------------------------------------------------------------
> 
> We could fix this issue by waiting enough time(5s) for address
> to pass duplicate address detection.

netns tests disable DAD in setup so this shouldn't happen. It's quite
likely that the kernel doesn't have the following upstream patch-fix:

094009531612 ("ipv6: set all.accept_dad to 0 by default")

Thanks,
Alexey