kernel_netlink: Allow to run inside non-privileged docker container

[christf]

Only set rp_filter to 0 if it contains a different value when
initializing new interfaces. This is helpful to run babeld inside docker
without --privileged.

[jech]

Why is the test not needed in the !setup branch of the if?

[christf]

On Thu, Oct 25, 2018 at 05:47:52PM +0000, Juliusz Chroboczek wrote: Why is the test not needed in the !setup branch of the if?

Whether it is necessary or not is not entirely clear. I did not touch the !setup branch because there the return code of the function is discarded in the caller when tearing down interfaces. There will still be a warning issued but babeld will continue to work fine. Thinking about this again, it is likely cleaner to do this properly. Fortunately there already is a check in place that just needs minor tweaking.

…

-- () ascii ribbon campaign - against html e-mail /\ against proprietary attachments

[jech]

Thanks, applied with minor tweaks (in branch xroute-nlogn, soon to become master).