Re: [PATCH v9 1/5] rust: types: Add Ownable/Owned types

[Oliver Mangold]

On 250409 1034, Andreas Hindborg wrote:
> Hi Oliver,
> 

Hi Andreas,

> "Oliver Mangold" <oliver.mangold@xxxxx> writes:
> 
> > From: Asahi Lina <lina@xxxxxxxxxxxxx>
> >
> > By analogy to AlwaysRefCounted and ARef, an Ownable type is a (typically
> > C FFI) type that *may* be owned by Rust, but need not be. Unlike
> > AlwaysRefCounted, this mechanism expects the reference to be unique
> > within Rust, and does not allow cloning.
> >
> > Conceptually, this is similar to a KBox<T>, except that it delegates
> > resource management to the T instead of using a generic allocator.
> >
> > Link: https://lore.kernel.org/all/20250202-rust-page-v1-1-e3170d7fe55e@xxxxxxxxxxxxx/
> > Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
> > [ om:
> >   - split code into separate file and `pub use` it from types.rs
> >   - make from_raw() and into_raw() public
> >   - fixes to documentation
> > ]
> > Signed-off-by: Oliver Mangold <oliver.mangold@xxxxx>
> > Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>
> > ---
> >  rust/kernel/lib.rs     |   1 +
> >  rust/kernel/ownable.rs | 117 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  rust/kernel/types.rs   |   2 +
> >  3 files changed, 120 insertions(+)
> 
> I would suggest moving ownable.rs to rust/kernel/types/ownable.rs and
> then moving `pub mod ownable` to types.rs.

Yes, that makes more sense.

> I am not sure we need the non-null invariant here, since it is an
> invariant of `NonNull`. The rest is fine.

> I would drop 'pointer' in 'a unique `&mut T` ~pointer~' here. '`&mut T`'
> is sufficient alone.

> Like here, I think this is correct (without the pointer wording).

> This part "the underlying object is acquired" is unclear to me. How about:
> 
>   Callers must ensure that *ownership of* the underlying object is acquired.

Agree. I will fix these.

Best,

Oliver