Commit 1a8076ac authored by Benno Lossin's avatar Benno Lossin Committed by Miguel Ojeda
Browse files

rust: init: make `PinInit<T, E>` a supertrait of `Init<T, E>` 



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: default avatarMartin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarGary Guo <gary@garyguo.net>
Signed-off-by: default avatarBenno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230814084602.25699-12-benno.lossin@proton.me


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 2e704f18

rust/kernel/init.rs

+8 −13
Original line number Diff line number Diff line
@@ -799,7 +799,7 @@ 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
@@ -810,18 +810,6 @@ 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
@@ -964,6 +952,13 @@ unsafe impl<T, E> Init<T, E> for T { 
    }

}



// 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

rust/kernel/init/__internal.rs

+12 −0
Original line number Diff line number Diff line
@@ -32,6 +32,18 @@ where 
    }

}



// 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.

///