Re: [PATCH v8 5/5] selftests/io_uring: add a bpf io_uring selftest

[Pavel Begunkov <asml.silence@gmail.com>]

On 2/20/26 17:45, Alexei Starovoitov wrote:
> On Fri, Feb 20, 2026 at 3:41 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
>>
>> I had such examples, but selftests is not the best place for that.
>> It can use abstractions, and I want to make them reusable instead
>> of people copy-pasting from selftests.
> 
> Sure, but please still post them as extra patches so it's easier
> to see what's the end result.
> 
> Also please reply to that thread:
> https://lore.kernel.org/bpf/CALTww28QMg=YXqKWpWLZrLO+xiqOe3LGyput8dx68-dnQsxg=g@mail.gmail.com/
> 
> It's not clear to me whether your io_uring+bpf setup will work
> for Xiao's use case.
> I don't think we need 2 ways of doing it.

We discussed this with Ming on the list before, that's one of the use
cases I target as well, there is no reason why it shouldn't work. The
difference is that this approach gives a flexible framework for
extensibility and covers a good bunch of other needs, which is exactly
the reason I moved from a BPF opcode approach, while Ming's proposal is
more specific but argued to be a way easier to plug into ublk servers.
If you ask me, we need a solution that covers a broader spectrum of
use cases, but I guess it all can be argued in either way.

But it'd be interesting to discuss how a BPF abstraction around
registered buffers should look like. E.g. passing an index to
all kfuncs like that, or making it a KF_ACQUIRE/RELEASE object, or
maybe something else. I'll reply later.

-- 
Pavel Begunkov