Messages in this thread Patch in this message |  | | Date | Sat, 31 Dec 2022 19:52:20 +0000 | From | Gary Guo <> | Subject | Re: [PATCH 7/7] rust: sync: add support for dispatching on Arc and ArcBorrow. |
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On Wed, 28 Dec 2022 06:03:46 +0000 Wedson Almeida Filho <wedsonaf@gmail.com> wrote:
> Trait objects (`dyn T`) require trait `T` to be "object safe". One of > the requirements for "object safety" is that the receiver have one of > the allowed types. This commit adds `Arc<T>` and `ArcBorrow<'_, T>` to > the list of allowed types. > > Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
> --- > rust/kernel/lib.rs | 1 + > rust/kernel/sync/arc.rs | 20 ++++++++++++++++++-- > 2 files changed, 19 insertions(+), 2 deletions(-) > > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index 4bde65e7b06b..e0b0e953907d 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -15,6 +15,7 @@ > #![feature(allocator_api)] > #![feature(coerce_unsized)] > #![feature(core_ffi_c)] > +#![feature(dispatch_from_dyn)] > #![feature(receiver_trait)] > #![feature(unsize)] > > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs > index 832bafc74a90..ff73f9240ca1 100644 > --- a/rust/kernel/sync/arc.rs > +++ b/rust/kernel/sync/arc.rs > @@ -92,9 +92,15 @@ use core::{ > /// Coercion from `Arc<Example>` to `Arc<dyn MyTrait>`: > /// > /// ``` > -/// use kernel::sync::Arc; > +/// use kernel::sync::{Arc, ArcBorrow}; > +/// > +/// trait MyTrait { > +/// // Trait has a function whose `self` type is `Arc<Self>`. > +/// fn example1(self: Arc<Self>) {} > /// > -/// trait MyTrait {} > +/// // Trait has a function whose `self` type is `ArcBorrow<'_, Self>`. > +/// fn example2(self: ArcBorrow<'_, Self>) {} > +/// } > /// > /// struct Example; > /// impl MyTrait for Example {} > @@ -123,6 +129,9 @@ impl<T: ?Sized> core::ops::Receiver for Arc<T> {} > // dynamically-sized type (DST) `U`. > impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::CoerceUnsized<Arc<U>> for Arc<T> {} > > +// This is to allow `Arc<U>` to be dispatched on when `Arc<T>` can be coerced into `Arc<U>`. > +impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<Arc<U>> for Arc<T> {} > + > // SAFETY: It is safe to send `Arc<T>` to another thread when the underlying `T` is `Sync` because > // it effectively means sharing `&T` (which is safe because `T` is `Sync`); additionally, it needs > // `T` to be `Send` because any thread that has an `Arc<T>` may ultimately access `T` directly, for > @@ -297,6 +306,13 @@ pub struct ArcBorrow<'a, T: ?Sized + 'a> { > // This is to allow [`ArcBorrow`] (and variants) to be used as the type of `self`. > impl<T: ?Sized> core::ops::Receiver for ArcBorrow<'_, T> {} > > +// This is to allow `ArcBorrow<U>` to be dispatched on when `ArcBorrow<T>` can be coerced into > +// `ArcBorrow<U>`. > +impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<ArcBorrow<'_, U>> > + for ArcBorrow<'_, T> > +{ > +} > + > impl<T: ?Sized> Clone for ArcBorrow<'_, T> { > fn clone(&self) -> Self { > *self
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