Re: [PATCH V2 3/5] ublk: use flexible array for ublk_queue.ios

[Ming Lei <ming.lei@redhat.com>]

On Tue, Oct 28, 2025 at 02:52:25PM -0700, Caleb Sander Mateos wrote:
> On Tue, Oct 28, 2025 at 1:57 AM Ming Lei <ming.lei@redhat.com> wrote:
> >
> > Convert ublk_queue to use DECLARE_FLEX_ARRAY for the ios field and
> > use struct_size() for allocation, following kernel best practices.
> >
> > Changes in this commit:
> >
> > 1. Convert ios field from "struct ublk_io ios[]" to use
> >    DECLARE_FLEX_ARRAY(struct ublk_io, ios) for consistency with
> >    modern kernel style.
> 
> Documentation/process/deprecated.rst suggests that
> DECLARE_FLEX_ARRAY() is discouraged except in the niche cases when
> it's necessary (which don't apply here). Or am I misunderstanding
> something?

You are right, DECLARE_FLEX_ARRAY is only needed:

```
when the flexible array is either alone in a struct or is part of a union.
```

> However, struct ublk_io ios[] does seem like a good use
> case for __counted_by().

Good point!

Thanks, 
Ming