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author | Benno Lossin <benno.lossin@proton.me> | 2023-08-14 08:47:15 +0000 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2023-08-21 14:31:49 +0200 |
commit | 9e49439077fe0a9aa062e682193b1f3257b314e2 (patch) | |
tree | 19d5a38c93c2ff2f448435544ab39241521bfa41 | |
parent | 35e7fca2ff59d9d8f036aba3dcf5c34beb79fdb8 (diff) | |
download | linux-stable-9e49439077fe0a9aa062e682193b1f3257b314e2.tar.gz linux-stable-9e49439077fe0a9aa062e682193b1f3257b314e2.tar.bz2 linux-stable-9e49439077fe0a9aa062e682193b1f3257b314e2.zip |
rust: init: add functions to create array initializers
Add two functions `pin_init_array_from_fn` and `init_array_from_fn` that
take a function that generates initializers for `T` from `usize`, the added
functions then return an initializer for `[T; N]` where every element is
initialized by an element returned from the generator function.
Suggested-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230814084602.25699-9-benno.lossin@proton.me
[ Cleaned a couple trivial nits. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
-rw-r--r-- | rust/kernel/init.rs | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 33f2666d5bae..429b485d8825 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -202,6 +202,7 @@ use crate::{ error::{self, Error}, sync::UniqueArc, + types::ScopeGuard, }; use alloc::boxed::Box; use core::{ @@ -867,6 +868,93 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> { unsafe { init_from_closure(|_| Ok(())) } } +/// Initializes an array by initializing each element via the provided initializer. +/// +/// # Examples +/// +/// ```rust +/// use kernel::{error::Error, init::init_array_from_fn}; +/// let array: Box<[usize; 1_000]>= Box::init::<Error>(init_array_from_fn(|i| i)).unwrap(); +/// assert_eq!(array.len(), 1_000); +/// ``` +pub fn init_array_from_fn<I, const N: usize, T, E>( + mut make_init: impl FnMut(usize) -> I, +) -> impl Init<[T; N], E> +where + I: Init<T, E>, +{ + let init = move |slot: *mut [T; N]| { + let slot = slot.cast::<T>(); + // Counts the number of initialized elements and when dropped drops that many elements from + // `slot`. + let mut init_count = ScopeGuard::new_with_data(0, |i| { + // We now free every element that has been initialized before: + // SAFETY: The loop initialized exactly the values from 0..i and since we + // return `Err` below, the caller will consider the memory at `slot` as + // uninitialized. + unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(slot, i)) }; + }); + for i in 0..N { + let init = make_init(i); + // SAFETY: Since 0 <= `i` < N, it is still in bounds of `[T; N]`. + let ptr = unsafe { slot.add(i) }; + // SAFETY: The pointer is derived from `slot` and thus satisfies the `__init` + // requirements. + unsafe { init.__init(ptr) }?; + *init_count += 1; + } + init_count.dismiss(); + Ok(()) + }; + // SAFETY: The initializer above initializes every element of the array. On failure it drops + // any initialized elements and returns `Err`. + unsafe { init_from_closure(init) } +} + +/// Initializes an array by initializing each element via the provided initializer. +/// +/// # Examples +/// +/// ```rust +/// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex}; +/// let array: Arc<[Mutex<usize>; 1_000]>= +/// Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i))).unwrap(); +/// assert_eq!(array.len(), 1_000); +/// ``` +pub fn pin_init_array_from_fn<I, const N: usize, T, E>( + mut make_init: impl FnMut(usize) -> I, +) -> impl PinInit<[T; N], E> +where + I: PinInit<T, E>, +{ + let init = move |slot: *mut [T; N]| { + let slot = slot.cast::<T>(); + // Counts the number of initialized elements and when dropped drops that many elements from + // `slot`. + let mut init_count = ScopeGuard::new_with_data(0, |i| { + // We now free every element that has been initialized before: + // SAFETY: The loop initialized exactly the values from 0..i and since we + // return `Err` below, the caller will consider the memory at `slot` as + // uninitialized. + unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(slot, i)) }; + }); + for i in 0..N { + let init = make_init(i); + // SAFETY: Since 0 <= `i` < N, it is still in bounds of `[T; N]`. + let ptr = unsafe { slot.add(i) }; + // SAFETY: The pointer is derived from `slot` and thus satisfies the `__init` + // requirements. + unsafe { init.__pinned_init(ptr) }?; + *init_count += 1; + } + init_count.dismiss(); + Ok(()) + }; + // SAFETY: The initializer above initializes every element of the array. On failure it drops + // any initialized elements and returns `Err`. + unsafe { pin_init_from_closure(init) } +} + // SAFETY: Every type can be initialized by-value. unsafe impl<T, E> Init<T, E> for T { unsafe fn __init(self, slot: *mut T) -> Result<(), E> { |