Re: [PATCH 2/2] selftests/bpf: Skip bpffs debug iter checks when unavailable in test_bpffs

[Viktor Malik <vmalik@redhat.com>]

On 3/11/26 08:55, sun jian wrote:
> On Tue, Mar 10, 2026 at 8:32 PM Viktor Malik <vmalik@redhat.com> wrote:
>>
>> I don't think this is a good approach as it will mask genuine bugs that
>> would cause the files to be missing/inaccessible with one of the above
>> error codes.
>>
> Hi Viktor，
> 
> I don't think this change masks bugs in a silent way. It prints an explicit
> INFO line when maps.debug/progs.debug are unavailable due to
> EPERM/EACCES/ENOENT, and it still fails on other errors or unexpected
> iterator output.

Yeah but automatic CI doesn't care about INFO lines. It cares about
pass/fail status and in this case, the test could falsely appear as
passing, even though there's a bug in bpffs code causing the files not
to exist or have wrong permissions.

>> If you really need to execute the rest of the test cases in the file,
>> how about you split the test into subtests and then just add the failing
>> subtest to your DENYLIST?
> 
> Proper subtests  would require reworking the current fork-based flow to
> report SKIP/FAIL to the harness, which would be a larger refactor than
> intended here.

I don't think it would be such a big refactoring. You can still use
fork(), you just need to have separate `run` functions for different
subtests. True, the init/teardown phase would be somewhat duplicated but
I wouldn't see that as a big issue (and you can still factor it out).

> My goal is to keep this as a minimal change while still achieving the main
> purpose of this test: exercising the core bpffs operations (pinning and
> renameat2 semantics), which are independent of the debug iterator files,
> and clearly reporting when the iterator checks couldn't be performed.

That's exactly what subtests are for, at least in my view. You want to
check independent operations, you create a separate subtest for each.
That way, you can filter out some subtests if they don't pass in your
environment.