# Re: \[PATCH bpf-next v2 6/6\] selftests/bpf: fix file descriptor assertion in open\_tuntap helper

- From: Marcus Wichelmann \<hidden\>
- Date: 2025-02-19 14:59:04 
- List: netdev
- Page: https://ratatoskr.run/netdev/2025/02/2933865
- Thread: https://ratatoskr.run/netdev/2025/02/2930329/t.md

```text
Am 18.02.25 um 02:56 schrieb Willem de Bruijn:
> Marcus Wichelmann wrote:
>> [...]
>> When running the BPF selftests locally, this incorrect assertion was not
>> an issue, but the BPF kernel-patches CI failed because of this:
>>
>>    open_tuntap:FAIL:open(/dev/net/tun) unexpected open(/dev/net/tun):
>>    actual 0 <= expected 0
>
> Wow. What kind of environment is this that 0 is not assigned stdin.
>   
>> Signed-off-by: Marcus Wichelmann <redacted>
>
> The code makes sense.
>
> I suppose that if this condition can hit, then it can also affect
> existing lwt_* tests and thus should be a fix to commit 43a7c3ef8a15
> ("selftests/bpf: Add lwt_xmit tests for BPF_REDIRECT"), sent
> separately to bpf (not bpf-next)?
>
> Since it's a test and no failure was reported so far, maybe fine
> to just merge as part of this bpf-next series, not my call.
I'm not sure why this only became an issue after I added the
xdp_context_tuntap test and never before. This may have to do with
the order of test execution.

If nobody speaks up, I'll leave it in this patch series for now.

Marcus
```