Re: [PATCH 2/2] rust: pin-init: add pin projections to `#[pin_data]`

["Benno Lossin" <lossin@kernel.org>]

On Wed Sep 10, 2025 at 12:24 PM CEST, Alice Ryhl wrote:
> On Wed, Sep 10, 2025 at 12:23 PM Alice Ryhl <aliceryhl@google.com> wrote:
>>
>> On Fri, Sep 5, 2025 at 7:12 PM Benno Lossin <lossin@kernel.org> wrote:
>> >
>> > Make the `#[pin_data]` macro generate a `*Projection` struct that holds
>> > either `Pin<&mut Field>` or `&mut Field` for every field of the original
>> > struct. Which version is chosen depends on weather there is a `#[pin]`
>> > or not respectively. Access to this projected version is enabled through
>> > generating `fn project(self: Pin<&mut Self>) -> SelfProjection<'_>`.
>> >
>> > Link: https://github.com/Rust-for-Linux/pin-init/pull/75/commits/2d698367d646c7ede90e01aa22842c1002d017b3
>> > [ Adapt workqueue to use the new projection instead of its own, custom
>> >   one - Benno ]
>> > Signed-off-by: Benno Lossin <lossin@kernel.org>
>> > ---
>> >  rust/kernel/workqueue.rs    | 10 ++-----
>> >  rust/pin-init/src/macros.rs | 60 +++++++++++++++++++++++++++++++++++++
>> >  2 files changed, 62 insertions(+), 8 deletions(-)
>> >
>> > diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
>> > index b9343d5bc00f..6ca14c629643 100644
>> > --- a/rust/kernel/workqueue.rs
>> > +++ b/rust/kernel/workqueue.rs
>> > @@ -356,18 +356,12 @@ struct ClosureWork<T> {
>> >      func: Option<T>,
>> >  }
>> >
>> > -impl<T> ClosureWork<T> {
>> > -    fn project(self: Pin<&mut Self>) -> &mut Option<T> {
>> > -        // SAFETY: The `func` field is not structurally pinned.
>> > -        unsafe { &mut self.get_unchecked_mut().func }
>> > -    }
>> > -}
>> > -
>> >  impl<T: FnOnce()> WorkItem for ClosureWork<T> {
>> >      type Pointer = Pin<KBox<Self>>;
>> >
>> >      fn run(mut this: Pin<KBox<Self>>) {
>> > -        if let Some(func) = this.as_mut().project().take() {
>> > +        if let Some(func) = this.as_mut().project().func.take() {
>> > +            // if let Some(func) = this.as_mut().project_func().take() {
>
> Spurious comment.

Oh yeah, will remove on apply.

---
Cheers,
Benno