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authorBenno Lossin <benno.lossin@proton.me>2023-08-14 08:47:15 +0000
committerMiguel Ojeda <ojeda@kernel.org>2023-08-21 14:31:49 +0200
commit9e49439077fe0a9aa062e682193b1f3257b314e2 (patch)
tree19d5a38c93c2ff2f448435544ab39241521bfa41 /rust
parent35e7fca2ff59d9d8f036aba3dcf5c34beb79fdb8 (diff)
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>
Diffstat (limited to 'rust')
-rw-r--r--rust/kernel/init.rs88
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> {