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rust: pin-init: add raw_init and raw_try_init and recommend over __init

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The `__init` method is not designed to be a public API (existence of "__"
is a hint for this); but currently there is no other API that allows raw
initialization on pointers. Add `raw_init` and `raw_try_init` and recommend
people to use this instead if raw pointer initialization is needed.

Link: https://patch.msgid.link/20260729-merge-init-v2-3-26adf47109e7@garyguo.net
[ Renamed from `ptr_[try_]init` to `raw_[try_]init`. - Gary ]
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
This commit is contained in:
Gary Guo
2026-07-29 16:38:45 +01:00
parent 91665820d9
commit d5492db2bf
2 changed files with 34 additions and 3 deletions
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5
rust/pin-init/examples/static_init.rs
View File

@@ -59,7 +59,7 @@ fn deref(&self) -> &Self::Target {
println!("doing init");
let ptr = self.cell.get().cast::<T>();
match self.init.take() {
Some(f) => unsafe { f.__init(ptr).unwrap() },
Some(f) => unsafe { pin_init::raw_init(ptr, f) },
None => unsafe { core::hint::unreachable_unchecked() },
}
self.present.set(true);
@@ -74,7 +74,8 @@ unsafe impl PinInit<CMutex<usize>> for CountInit {
unsafe fn __init(self, slot: *mut CMutex<usize>) -> Result<(), core::convert::Infallible> {
let init = CMutex::new(0);
std::thread::sleep(std::time::Duration::from_millis(1000));
unsafe { init.__init(slot) }
unsafe { pin_init::raw_init(slot, init) };
Ok(())
}
}

32
rust/pin-init/src/lib.rs
View File

@@ -917,7 +917,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
///
/// Same as `__init`.
#[inline(always)]
#[cfg_attr(not(kernel), deprecated = "use `__init` instead")]
#[cfg_attr(not(kernel), deprecated = "use `raw_try_init` instead")]
unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
// SAFETY: Per safety requirement.
unsafe { self.__init(slot) }
@@ -925,6 +925,8 @@ unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
/// Initializes `slot`.
///
/// It is not recommended to call this directly. Use [`raw_init`] or [`raw_try_init`].
///
/// # Safety
///
/// - `slot` is a valid pointer to uninitialized memory.
@@ -960,6 +962,34 @@ fn pin_chain<F>(self, f: F) -> ChainPinInit<Self, F, T, E>
}
}
/// Initializes `slot` with an initializer.
///
/// # Safety
///
/// - `slot` is a valid pointer to uninitialized memory.
/// - `slot` will not move until it is dropped, i.e. it will be pinned.
/// If `init` implements `Init<T, E>`, this requirement is cancelled and it may be moved.
#[inline(always)]
pub unsafe fn raw_init<T>(slot: *mut T, init: impl PinInit<T>) {
// SAFETY: Per safety requirement.
unsafe { init.__init(slot).unwrap_or_else(|e| match e {}) }
}
/// Fallibly initializes `slot` with an initializer.
///
/// # Safety
///
/// - `slot` is a valid pointer to uninitialized memory.
/// - the caller does not touch `slot` when `Err` is returned, they are only permitted to
/// deallocate.
/// - `slot` will not move until it is dropped, i.e. it will be pinned.
/// If `init` implements `Init<T, E>`, this requirement is cancelled and it may be moved.
#[inline(always)]
pub unsafe fn raw_try_init<T, E>(slot: *mut T, init: impl PinInit<T, E>) -> Result<(), E> {
// SAFETY: Per safety requirement.
unsafe { init.__init(slot) }
}
/// An initializer returned by [`PinInit::pin_chain`].
pub struct ChainPinInit<I, F, T: ?Sized, E>(I, F, __internal::PhantomInvariant<(E, T)>);