Subject: Re: [PATCH net-next v1 0/2] selftests: rds: refactor and expand rds selftests test

From: Jakub Kicinski <[email-masked]>
Date: Wed, 4 Mar 2026 10:32:12 -0800

On Wed, 4 Mar 2026 02:50:34 +0000 Allison Henderson wrote:
> I didnt know it was causing you grief, but I am happy to work with
> you to adapt it.  RDS is a little unique in that the network topology
> defines the underlying transport it uses.  If you were to run it with
> just a pair of veth interfaces on a single host or vm, then you will
> only be using the loop back transport in rds.ko.  In order to get it
> to load and test rds_tcp.ko, we need the endpoints to be in separate
> network namespaces so that the destination IP isn't seen as local. So
> the test case does this by forking server/client processes across
> name spaces.  There really isnt a rush on this series, so if you
> think we should do some refactoring/cleanup for ksft first that is
> fine.  Let me know your thoughts.

IIUC the need to set up a veth + 2 name spaces topology is very common.
We have bash "libraries" / helpers in various lib.sh files to do it.
Python libs also have some support (tho the default linking there is
by pairing two netdevsim devices).

Well, maybe to be clear I should say that we _even_ have support in
libraries for this. Not really strongly opposed to you rolling your own
way of setting up the namespaces at this point. I primarily care about
us being able to execute all your tests in our CI, with standard ksft
commands. Maybe I did something wrong but

 make -C tools/testing/selftests TARGETS=net/rds run_tests

did not work for me.