Commit 619db96d authored by Benno Lossin's avatar Benno Lossin
Browse files

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



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: default avatarGary Guo <gary@garyguo.net>
Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarBenno Lossin <lossin@kernel.org>
parent d49c5636

rust/kernel/workqueue.rs

+1 −8
Original line number Diff line number Diff line
@@ -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)()

        }

    }

rust/pin-init/src/macros.rs

+61 −0
Original line number Diff line number Diff line
@@ -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 @@ fn drop(&mut self) { 
            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)*),