Messages in this thread Patch in this message | | | Date | Sun, 6 Aug 2023 17:09:03 +0100 | From | Gary Guo <> | Subject | Re: [PATCH v3 11/13] rust: init: make `PinInit<T, E>` a supertrait of `Init<T, E>` |
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On Sat, 29 Jul 2023 09:10:22 +0000 Benno Lossin <benno.lossin@proton.me> wrote:
> Remove the blanket implementation of `PinInit<T, E> for I where I: > Init<T, E>`. This blanket implementation prevented custom types that > implement `PinInit`. > > Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
> --- > v2 -> v3: > - add blank missing line, > - added Reviewed-by's from Martin and Alice. > > rust/kernel/init.rs | 21 ++++++++------------- > rust/kernel/init/__internal.rs | 12 ++++++++++++ > 2 files changed, 20 insertions(+), 13 deletions(-) > > diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs > index 06ecab4901f2..040dc9a5f9fd 100644 > --- a/rust/kernel/init.rs > +++ b/rust/kernel/init.rs > @@ -807,7 +807,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized { > /// > /// [`Arc<T>`]: crate::sync::Arc > #[must_use = "An initializer must be used in order to create its value."] > -pub unsafe trait Init<T: ?Sized, E = Infallible>: Sized { > +pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> { > /// Initializes `slot`. > /// > /// # Safety > @@ -818,18 +818,6 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: Sized { > unsafe fn __init(self, slot: *mut T) -> Result<(), E>; > } > > -// SAFETY: Every in-place initializer can also be used as a pin-initializer. > -unsafe impl<T: ?Sized, E, I> PinInit<T, E> for I > -where > - I: Init<T, E>, > -{ > - unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> { > - // SAFETY: `__init` meets the same requirements as `__pinned_init`, except that it does not > - // require `slot` to not move after init. > - unsafe { self.__init(slot) } > - } > -} > - > /// Creates a new [`PinInit<T, E>`] from the given closure. > /// > /// # Safety > @@ -971,6 +959,13 @@ unsafe fn __init(self, slot: *mut T) -> Result<(), E> { > } > } > > +// SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`. > +unsafe impl<T, E> PinInit<T, E> for T { > + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> { > + unsafe { self.__init(slot) } > + } > +} > + > /// Smart pointer that can initialize memory in-place. > pub trait InPlaceInit<T>: Sized { > /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this > diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs > index 7abd1fb65e41..12e195061525 100644 > --- a/rust/kernel/init/__internal.rs > +++ b/rust/kernel/init/__internal.rs > @@ -32,6 +32,18 @@ unsafe fn __init(self, slot: *mut T) -> Result<(), E> { > } > } > > +// SAFETY: While constructing the `InitClosure`, the user promised that it upholds the > +// `__pinned_init` invariants. > +unsafe impl<T: ?Sized, F, E> PinInit<T, E> for InitClosure<F, T, E> > +where > + F: FnOnce(*mut T) -> Result<(), E>, > +{ > + #[inline] > + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> { > + (self.0)(slot) > + } > +} > + > /// This trait is only implemented via the `#[pin_data]` proc-macro. It is used to facilitate > /// the pin projections within the initializers. > ///
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