[PATCH v5 11/26] rust: alloc: remove `BoxExt` extension

Danilo Krummrich
2024-08-12T18:25:07Z

Now that all existing `Box` users were moved to the kernel `Box` type,
remove the `BoxExt` extension and all other related extensions.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
rust/kernel/alloc.rs | 1 -
rust/kernel/alloc/box_ext.rs | 56 ------------------------------------
rust/kernel/init.rs | 34 +---------------------
rust/kernel/lib.rs | 1 -
rust/kernel/prelude.rs | 4 +--
rust/kernel/types.rs | 23 ---------------
6 files changed, 3 insertions(+), 116 deletions(-)
delete mode 100644 rust/kernel/alloc/box_ext.rs

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index ed46b69204d0..47cab5bd803e 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -4,7 +4,6 @@

#[cfg(not(any(test, testlib)))]
pub mod allocator;
-pub mod box_ext;
pub mod kbox;
pub mod vec_ext;

diff --git a/rust/kernel/alloc/box_ext.rs b/rust/kernel/alloc/box_ext.rs
deleted file mode 100644
index 829cb1c1cf9e..000000000000
--- a/rust/kernel/alloc/box_ext.rs
+++ /dev/null
@@ -1,56 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Extensions to [`Box`] for fallible allocations.
-
-use super::{AllocError, Flags};
-use alloc::boxed::Box;
-use core::mem::MaybeUninit;
-
-/// Extensions to [`Box`].
-pub trait BoxExt<T>: Sized {
- /// Allocates a new box.
- ///
- /// The allocation may fail, in which case an error is returned.
- fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
-
- /// Allocates a new uninitialised box.
- ///
- /// The allocation may fail, in which case an error is returned.
- fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
-}
-
-impl<T> BoxExt<T> for Box<T> {
- fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
- let b = <Self as BoxExt<_>>::new_uninit(flags)?;
- Ok(Box::write(b, x))
- }
-
- #[cfg(any(test, testlib))]
- fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
- Ok(Box::new_uninit())
- }
-
- #[cfg(not(any(test, testlib)))]
- fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
- let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 {
- core::ptr::NonNull::<_>::dangling().as_ptr()
- } else {
- let layout = core::alloc::Layout::new::<MaybeUninit<T>>();
-
- // SAFETY: Memory is being allocated (first arg is null). The only other source of
- // safety issues is sleeping on atomic context, which is addressed by klint. Lastly,
- // the type is not a SZT (checked above).
- let ptr =
- unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) };
- if ptr.is_null() {
- return Err(AllocError);
- }
-
- ptr.cast::<MaybeUninit<T>>()
- };
-
- // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
- // zero-sized types, we use `NonNull::dangling`.
- Ok(unsafe { Box::from_raw(ptr) })
- }
-}
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index d3639243f8c7..eb55787eddee 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -211,12 +211,11 @@
//! [`pin_init!`]: crate::pin_init!

use crate::{
- alloc::{box_ext::BoxExt, AllocError, Flags, KBox},
+ alloc::{AllocError, Flags, KBox},
error::{self, Error},
sync::UniqueArc,
types::{Opaque, ScopeGuard},
};
-use alloc::boxed::Box;
use core::{
cell::UnsafeCell,
convert::Infallible,
@@ -589,7 +588,6 @@ macro_rules! pin_init {
/// # Examples
///
/// ```rust
-/// # #![feature(new_uninit)]
/// use kernel::{init::{self, PinInit}, error::Error};
/// #[pin_data]
/// struct BigBuf {
@@ -1149,36 +1147,6 @@ fn init<E>(init: impl Init<T, E>, flags: Flags) -> error::Result<Self>
}
}

-impl<T> InPlaceInit<T> for Box<T> {
- #[inline]
- fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
- where
- E: From<AllocError>,
- {
- let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
- 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>, flags: Flags) -> Result<Self, E>
- where
- E: From<AllocError>,
- {
- let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
- 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>, flags: Flags) -> Result<Pin<Self>, E>
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 274bdc1b0a82..042f05c45214 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -14,7 +14,6 @@
#![no_std]
#![feature(coerce_unsized)]
#![feature(dispatch_from_dyn)]
-#![feature(new_uninit)]
#![feature(receiver_trait)]
#![feature(unsize)]

diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index 39f9331a48e2..a8018ef2e691 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,10 +14,10 @@
#[doc(no_inline)]
pub use core::pin::Pin;

-pub use crate::alloc::{box_ext::BoxExt, flags::*, vec_ext::VecExt, KBox, KVBox, VBox};
+pub use crate::alloc::{flags::*, vec_ext::VecExt, KBox, KVBox, VBox};

#[doc(no_inline)]
-pub use alloc::{boxed::Box, vec::Vec};
+pub use alloc::vec::Vec;

#[doc(no_inline)]
pub use macros::{module, pin_data, pinned_drop, vtable, Zeroable};
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index bd189d646adb..f48704db33c1 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -3,7 +3,6 @@
//! Kernel types.

use crate::init::{self, PinInit};
-use alloc::boxed::Box;
use core::{
cell::UnsafeCell,
marker::{PhantomData, PhantomPinned},
@@ -67,28 +66,6 @@ unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> {
}
}

-impl<T: 'static> ForeignOwnable for Box<T> {
- type Borrowed<'a> = &'a T;
-
- fn into_foreign(self) -> *const core::ffi::c_void {
- Box::into_raw(self) as _
- }
-
- unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
- // SAFETY: The safety requirements for this function ensure that the object is still alive,
- // so it is safe to dereference the raw pointer.
- // The safety requirements of `from_foreign` also ensure that the object remains alive for
- // the lifetime of the returned value.
- unsafe { &*ptr.cast() }
- }
-
- unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
- // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
- // call to `Self::into_foreign`.
- unsafe { Box::from_raw(ptr as _) }
- }
-}
-
impl ForeignOwnable for () {
type Borrowed<'a> = ();

--
2.45.2