Re: [PATCH net-next v2 1/2] selftests: drv-net: devmem: fix 5-tuple flow steering

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 6 Aug 2026 13:05:49 -0700 Mina Almasry wrote:
> Yes the test fails, but it gets past the flow steering configuration problem.
> 
> And in the code, the change looks correct to me. If flow_steer is
> False, then we don't pass the -c arg to ncdevmem. ncdevmem is written
> so that if -c is not set, 5-tuple flow steering is not possible (the
> client side port is random), so it falls back to 3-tuple flow
> steering, which doesn't work on GVE or any other driver that supports
> only 5-tuple flow steering.
> 
> run_rx (devmem.check_rx test case) doesn't have this problem because
> it does `flow_steer=not hasattr(cfg, 'netns')`, but run_rx_hds has
> this problem because it forgets to override flow_steer at all. This
> patch fixes that.
> 
> To be honest while looking at this there were a few weird things. Like
> I'm not sure why the python arg is named `flow_steer` (it likely
> should be 5_tuple_flow_steer), and why flow_steer setting is tied to
> hasattr(cfg, 'netns'), it should be a proprety of the driver you're
> runing on (unless all in-netns drivers will support 3-tuple flow
> steering).

Could we clean this up and add explicit test cases for inserting
specific rule types? We want the one-sided-tuple format at Meta,
falling back silently would be a loss of signal.