1 files changed, 93 insertions, 30 deletions

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index bd6da02c7ab8..35d1e015848d 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -3,24 +3,47 @@
 //! Implementation of [`Box`].
 
 #[allow(unused_imports)] // Used in doc comments.
-use super::allocator::{KVmalloc, Kmalloc, Vmalloc, VmallocPageIter};
-use super::{AllocError, Allocator, Flags, NumaNode};
-use core::alloc::Layout;
-use core::borrow::{Borrow, BorrowMut};
-use core::marker::PhantomData;
-use core::mem::ManuallyDrop;
-use core::mem::MaybeUninit;
-use core::ops::{Deref, DerefMut};
-use core::pin::Pin;
-use core::ptr::NonNull;
-use core::result::Result;
-
-use crate::ffi::c_void;
-use crate::fmt;
-use crate::init::InPlaceInit;
-use crate::page::AsPageIter;
-use crate::types::ForeignOwnable;
-use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
+use super::allocator::{
+    KVmalloc,
+    Kmalloc,
+    Vmalloc,
+    VmallocPageIter, //
+};
+
+use super::{
+    AllocError,
+    Allocator,
+    Flags,
+    NumaNode, //
+};
+
+use crate::{
+    fmt,
+    page::AsPageIter,
+    prelude::*,
+    types::ForeignOwnable, //
+};
+
+use core::{
+    alloc::Layout,
+    borrow::{
+        Borrow,
+        BorrowMut, //
+    },
+    marker::PhantomData,
+    mem::{
+        ManuallyDrop,
+        MaybeUninit, //
+    },
+    ops::{
+        Deref,
+        DerefMut, //
+    },
+    ptr::NonNull,
+    result::Result, //
+};
+
+use pin_init::ZeroableOption;
 
 /// The kernel's [`Box`] type -- a heap allocation for a single value of type `T`.
 ///
@@ -256,6 +279,27 @@ where
         Ok(Box(ptr.cast(), PhantomData))
     }
 
+    /// Creates a new zero-initialized `Box<T, A>`.
+    ///
+    /// New memory is allocated with `A` and the [`__GFP_ZERO`] flag. The allocation may fail, in
+    /// which case an error is returned. For ZSTs no memory is allocated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let b = KBox::<[u8; 128]>::zeroed(GFP_KERNEL)?;
+    /// assert_eq!(*b, [0; 128]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn zeroed(flags: Flags) -> Result<Self, AllocError>
+    where
+        T: Zeroable,
+    {
+        // SAFETY: `__GFP_ZERO` guarantees the memory is zeroed; `T: Zeroable` guarantees that
+        // all-zeroes is a valid bit pattern for `T`.
+        Ok(unsafe { Self::new_uninit(flags | __GFP_ZERO)?.assume_init() })
+    }
+
     /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then `x` will be
     /// pinned in memory and can't be moved.
     #[inline]
@@ -274,7 +318,10 @@ where
     /// # Examples
     ///
     /// ```
-    /// use kernel::sync::{new_spinlock, SpinLock};
+    /// use kernel::sync::{
+    ///     new_spinlock,
+    ///     SpinLock, //
+    /// };
     ///
     /// struct Inner {
     ///     a: u32,
@@ -411,6 +458,7 @@ where
 {
     type Initialized = Box<T, A>;
 
+    #[inline]
     fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> {
         let slot = self.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
@@ -420,6 +468,7 @@ where
         Ok(unsafe { Box::assume_init(self) })
     }
 
+    #[inline]
     fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> {
         let slot = self.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
@@ -455,7 +504,7 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
+unsafe impl<T, A> ForeignOwnable for Box<T, A>
 where
     A: Allocator,
 {
@@ -465,8 +514,14 @@ where
         core::mem::align_of::<T>()
     };
 
-    type Borrowed<'a> = &'a T;
-    type BorrowedMut<'a> = &'a mut T;
+    type Borrowed<'a>
+        = &'a T
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = &'a mut T
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         Box::into_raw(self).cast()
@@ -494,13 +549,19 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+unsafe impl<T, A> ForeignOwnable for Pin<Box<T, A>>
 where
     A: Allocator,
 {
     const FOREIGN_ALIGN: usize = <Box<T, A> as ForeignOwnable>::FOREIGN_ALIGN;
-    type Borrowed<'a> = Pin<&'a T>;
-    type BorrowedMut<'a> = Pin<&'a mut T>;
+    type Borrowed<'a>
+        = Pin<&'a T>
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = Pin<&'a mut T>
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         // SAFETY: We are still treating the box as pinned.
@@ -567,7 +628,6 @@ where
 ///
 /// ```
 /// # use core::borrow::Borrow;
-/// # use kernel::alloc::KBox;
 /// struct Foo<B: Borrow<u32>>(B);
 ///
 /// // Owned instance.
@@ -595,7 +655,6 @@ where
 ///
 /// ```
 /// # use core::borrow::BorrowMut;
-/// # use kernel::alloc::KBox;
 /// struct Foo<B: BorrowMut<u32>>(B);
 ///
 /// // Owned instance.
@@ -660,9 +719,13 @@ where
 /// # Examples
 ///
 /// ```
-/// # use kernel::prelude::*;
-/// use kernel::alloc::allocator::VmallocPageIter;
-/// use kernel::page::{AsPageIter, PAGE_SIZE};
+/// use kernel::{
+///     alloc::allocator::VmallocPageIter,
+///     page::{
+///         AsPageIter,
+///         PAGE_SIZE, //
+///     }, //
+/// };
 ///
 /// let mut vbox = VBox::new((), GFP_KERNEL)?;
 ///