Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-24 21:21:41 +00:00
Code Issues Packages Projects Releases Wiki Activity

rust: init/sync: add InPlaceInit trait to pin-initialize smart pointers

Browse Source 
The `InPlaceInit` trait that provides two functions, for initializing
using `PinInit<T, E>` and `Init<T>`. It is implemented by `Arc<T>`,
`UniqueArc<T>` and `Box<T>`.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230408122429.1103522-9-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Benno Lossin 2023-04-08 12:25:56 +00:00 committed by Miguel Ojeda
parent fc6c6baa1f
commit 92c4a1e7e8
2 changed files with 139 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

128
rust/kernel/init.rs
View File

@ -114,10 +114,16 @@
//! [`impl Init<T, E>`]: Init
//! [`Opaque`]: kernel::types::Opaque
//! [`pin_data`]: ::macros::pin_data
//! [`UniqueArc<T>`]: kernel::sync::UniqueArc
use crate::{
error::{self, Error},
sync::UniqueArc,
};
use alloc::boxed::Box;
use core::{cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit, ptr};
use core::{
alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit,
pin::Pin, ptr,
};
#[doc(hidden)]
pub mod __internal;
@ -309,7 +315,6 @@ pub mod macros;
///
/// [`try_pin_init!`]: kernel::try_pin_init
/// [`NonNull<Self>`]: core::ptr::NonNull
/// [`Error`]: kernel::error::Error
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
@ -363,8 +368,6 @@ macro_rules! pin_init {
/// }
/// }
/// ```
///
/// [`Error`]: kernel::error::Error
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
@ -586,8 +589,6 @@ macro_rules! try_pin_init {
///
/// This initializer is for initializing data in-place that might later be moved. If you want to
/// pin-initialize, use [`pin_init!`].
///
/// [`Error`]: kernel::error::Error
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
@ -635,8 +636,6 @@ macro_rules! init {
/// }
/// }
/// ```
///
/// [`Error`]: kernel::error::Error
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
@ -842,7 +841,8 @@ macro_rules! try_init {
/// A pin-initializer for the type `T`.
///
/// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`].
/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`]. Use the [`InPlaceInit::pin_init`] function of a
/// smart pointer like [`Arc<T>`] on this.
///
/// Also see the [module description](self).
///
@ -861,7 +861,6 @@ macro_rules! try_init {
///
/// [`Arc<T>`]: crate::sync::Arc
/// [`Arc::pin_init`]: crate::sync::Arc::pin_init
/// [`UniqueArc<T>`]: kernel::sync::UniqueArc
#[must_use = "An initializer must be used in order to create its value."]
pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
/// Initializes `slot`.
@ -878,7 +877,8 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
/// An initializer for `T`.
///
/// To use this initializer, you will need a suitable memory location that can hold a `T`. This can
/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`]. Because [`PinInit<T, E>`] is a super trait, you can
/// be [`Box<T>`], [`Arc<T>`], [`UniqueArc<T>`]. Use the [`InPlaceInit::init`] function of a smart
/// pointer like [`Arc<T>`] on this. Because [`PinInit<T, E>`] is a super trait, you can
/// use every function that takes it as well.
///
/// Also see the [module description](self).
@ -903,7 +903,6 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
/// move the pointee after initialization.
///
/// [`Arc<T>`]: crate::sync::Arc
/// [`UniqueArc<T>`]: kernel::sync::UniqueArc
#[must_use = "An initializer must be used in order to create its value."]
pub unsafe trait Init<T: ?Sized, E = Infallible>: Sized {
/// Initializes `slot`.
@ -982,3 +981,106 @@ unsafe impl<T> Init<T> for T {
Ok(())
}
}
/// 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
/// type.
///
/// If `T: !Unpin` it will not be able to move afterwards.
fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
where
E: From<AllocError>;
/// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this
/// type.
///
/// If `T: !Unpin` it will not be able to move afterwards.
fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Pin<Self>>
where
Error: From<E>,
{
// SAFETY: We delegate to `init` and only change the error type.
let init = unsafe {
pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
};
Self::try_pin_init(init)
}
/// Use the given initializer to in-place initialize a `T`.
fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
where
E: From<AllocError>;
/// Use the given initializer to in-place initialize a `T`.
fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
where
Error: From<E>,
{
// SAFETY: We delegate to `init` and only change the error type.
let init = unsafe {
init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
};
Self::try_init(init)
}
}
impl<T> InPlaceInit<T> for Box<T> {
#[inline]
fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
where
E: From<AllocError>,
{
let mut this = Box::try_new_uninit()?;
let slot = this.as_mut_ptr();
// SAFETY: When init errors/panics, slot will get deallocated but not dropped,
// slot is valid and will not be moved, because we pin it later.
unsafe { init.__pinned_init(slot)? };
// SAFETY: All fields have been initialized.
Ok(unsafe { this.assume_init() }.into())
}
#[inline]
fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
where
E: From<AllocError>,
{
let mut this = Box::try_new_uninit()?;
let slot = this.as_mut_ptr();
// SAFETY: When init errors/panics, slot will get deallocated but not dropped,
// slot is valid.
unsafe { init.__init(slot)? };
// SAFETY: All fields have been initialized.
Ok(unsafe { this.assume_init() })
}
}
impl<T> InPlaceInit<T> for UniqueArc<T> {
#[inline]
fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
where
E: From<AllocError>,
{
let mut this = UniqueArc::try_new_uninit()?;
let slot = this.as_mut_ptr();
// SAFETY: When init errors/panics, slot will get deallocated but not dropped,
// slot is valid and will not be moved, because we pin it later.
unsafe { init.__pinned_init(slot)? };
// SAFETY: All fields have been initialized.
Ok(unsafe { this.assume_init() }.into())
}
#[inline]
fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
where
E: From<AllocError>,
{
let mut this = UniqueArc::try_new_uninit()?;
let slot = this.as_mut_ptr();
// SAFETY: When init errors/panics, slot will get deallocated but not dropped,
// slot is valid.
unsafe { init.__init(slot)? };
// SAFETY: All fields have been initialized.
Ok(unsafe { this.assume_init() })
}
}

24
rust/kernel/sync/arc.rs
View File

@ -17,6 +17,8 @@
use crate::{
bindings,
error::{self, Error},
init::{InPlaceInit, Init, PinInit},
types::{ForeignOwnable, Opaque},
};
use alloc::boxed::Box;
@ -166,6 +168,28 @@ impl<T> Arc<T> {
// `Arc` object.
Ok(unsafe { Self::from_inner(Box::leak(inner).into()) })
}
/// Use the given initializer to in-place initialize a `T`.
///
/// If `T: !Unpin` it will not be able to move afterwards.
#[inline]
pub fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Self>
where
Error: From<E>,
{
UniqueArc::pin_init(init).map(|u| u.into())
}
/// Use the given initializer to in-place initialize a `T`.
///
/// This is equivalent to [`pin_init`], since an [`Arc`] is always pinned.
#[inline]
pub fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
where
Error: From<E>,
{
UniqueArc::init(init).map(|u| u.into())
}
}
impl<T: ?Sized> Arc<T> {