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rust: pin-init: add pin projections to #[pin_data]

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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<'_>`.

[ Adapt workqueue to use the new projection instead of its own, custom
  one - Benno ]

Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Benno Lossin <lossin@kernel.org>
This commit is contained in:
Benno Lossin
2025-09-05 19:12:07 +02:00
parent d49c56368c
commit 619db96daf
2 changed files with 62 additions and 8 deletions
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9
rust/kernel/workqueue.rs
View File

@@ -356,18 +356,11 @@ 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() {
(func)()
}
}

61
rust/pin-init/src/macros.rs
View File

@@ -831,6 +831,17 @@ macro_rules! __pin_data {
$($fields)*
}
$crate::__pin_data!(make_pin_projections:
@vis($vis),
@name($name),
@impl_generics($($impl_generics)*),
@ty_generics($($ty_generics)*),
@decl_generics($($decl_generics)*),
@where($($whr)*),
@pinned($($pinned)*),
@not_pinned($($not_pinned)*),
);
// We put the rest into this const item, because it then will not be accessible to anything
// outside.
const _: () = {
@@ -980,6 +991,56 @@ macro_rules! __pin_data {
stringify!($($rest)*),
);
};
(make_pin_projections:
@vis($vis:vis),
@name($name:ident),
@impl_generics($($impl_generics:tt)*),
@ty_generics($($ty_generics:tt)*),
@decl_generics($($decl_generics:tt)*),
@where($($whr:tt)*),
@pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?),
@not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?),
) => {
$crate::macros::paste! {
#[doc(hidden)]
$vis struct [< $name Projection >] <'__pin, $($decl_generics)*> {
$($(#[$($p_attr)*])* $pvis $p_field : ::core::pin::Pin<&'__pin mut $p_type>,)*
$($(#[$($attr)*])* $fvis $field : &'__pin mut $type,)*
___pin_phantom_data: ::core::marker::PhantomData<&'__pin mut ()>,
}
impl<$($impl_generics)*> $name<$($ty_generics)*>
where $($whr)*
{
/// Pin-projects all fields of `Self`.
///
/// These fields are structurally pinned:
$(#[doc = ::core::concat!(" - `", ::core::stringify!($p_field), "`")])*
///
/// These fields are **not** structurally pinned:
$(#[doc = ::core::concat!(" - `", ::core::stringify!($field), "`")])*
#[inline]
$vis fn project<'__pin>(
self: ::core::pin::Pin<&'__pin mut Self>,
) -> [< $name Projection >] <'__pin, $($ty_generics)*> {
// SAFETY: we only give access to `&mut` for fields not structurally pinned.
let this = unsafe { ::core::pin::Pin::get_unchecked_mut(self) };
[< $name Projection >] {
$(
// SAFETY: `$p_field` is structurally pinned.
$(#[$($p_attr)*])*
$p_field : unsafe { ::core::pin::Pin::new_unchecked(&mut this.$p_field) },
)*
$(
$(#[$($attr)*])*
$field : &mut this.$field,
)*
___pin_phantom_data: ::core::marker::PhantomData,
}
}
}
}
};
(make_pin_data:
@pin_data($pin_data:ident),
@impl_generics($($impl_generics:tt)*),