Messages in this thread |  | | Date | Sat, 28 Jan 2023 12:15:39 +0100 | Subject | Re: [PATCH 5/5] rust: types: implement `ForeignOwnable` for `Arc<T>` | From | "Vincenzo Palazzo" <> |
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On Thu Jan 19, 2023 at 6:40 PM CET, Wedson Almeida Filho wrote: > This allows us to hand ownership of Rust ref-counted objects to > the C side of the kernel. > > Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com> > --- Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> rust/kernel/sync/arc.rs | 32 +++++++++++++++++++++++++++++++- > 1 file changed, 31 insertions(+), 1 deletion(-) > > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs > index ff73f9240ca1..519a6ec43644 100644 > --- a/rust/kernel/sync/arc.rs > +++ b/rust/kernel/sync/arc.rs > @@ -15,7 +15,11 @@ > //! > //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html > > -use crate::{bindings, error::Result, types::Opaque}; > +use crate::{ > + bindings, > + error::Result, > + types::{ForeignOwnable, Opaque}, > +}; > use alloc::boxed::Box; > use core::{ > marker::{PhantomData, Unsize}, > @@ -189,6 +193,32 @@ impl<T: ?Sized> Arc<T> { > } > } > > +impl<T: 'static> ForeignOwnable for Arc<T> { > + type Borrowed<'a> = ArcBorrow<'a, T>; > + > + fn into_foreign(self) -> *const core::ffi::c_void { > + ManuallyDrop::new(self).ptr.as_ptr() as _ > + } > + > + unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> { > + // SAFETY: By the safety requirement of this function, we know that `ptr` came from > + // a previous call to `Arc::into_foreign`. > + let inner = NonNull::new(ptr as *mut ArcInner<T>).unwrap(); > + > + // SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive > + // for the lifetime of the returned value. Additionally, the safety requirements of > + // `ForeignOwnable::borrow_mut` ensure that no new mutable references are created. > + unsafe { ArcBorrow::new(inner) } > + } > + > + unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self { > + // SAFETY: By the safety requirement of this function, we know that `ptr` came from > + // a previous call to `Arc::into_foreign`, which owned guarantees that `ptr` is valid and > + // owns a reference. > + unsafe { Self::from_inner(NonNull::new(ptr as _).unwrap()) } > + } > +} > + > impl<T: ?Sized> Deref for Arc<T> { > type Target = T; > > -- > 2.34.1
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