Merge tag 'alloc-next-v6.17-2025-07-15' of https://github.com/Rust-for-Linux/linux into rust-next

Pull alloc and DMA updates from Danilo Krummrich:

  Box:
   - Implement Borrow / BorrowMut for Box<T, A>.

  Vec:
   - Implement Default for Vec<T, A>.

   - Implement Borrow / BorrowMut for Vec<T, A>.

  DMA:
   - Clarify wording and be consistent in 'coherent' nomenclature.

   - Convert the read!() / write!() macros to return a Result.

   - Add as_slice() / write() methods in CoherentAllocation.

   - Fix doc-comment of dma_handle().

   - Expose count() and size() in CoherentAllocation and add the
     corresponding type invariants.

   - Implement CoherentAllocation::dma_handle_with_offset().

   - Require mutable reference for as_slice_mut() and write().

  MAINTAINERS:
   - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo
     Stoakes as reviewers (thanks everyone).

* tag 'alloc-next-v6.17-2025-07-15' of https://github.com/Rust-for-Linux/linux:
  MAINTAINERS: add mm folks as reviewers to rust alloc
  rust: dma: require mutable reference for as_slice_mut() and write()
  rust: dma: add dma_handle_with_offset method to CoherentAllocation
  rust: dma: expose the count and size of CoherentAllocation
  rust: dma: fix doc-comment of dma_handle()
  rust: dma: add as_slice/write functions for CoherentAllocation
  rust: dma: convert the read/write macros to return Result
  rust: dma: clarify wording and be consistent in `coherent` nomenclature
  rust: alloc: implement `Borrow` and `BorrowMut` for `KBox`
  rust: alloc: implement `Borrow` and `BorrowMut` for `Vec`
  rust: vec: impl Default for Vec with any allocator

2 files changed, 111 insertions, 1 deletions

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index bffe72f44cb3..856d05aa60f1 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -6,6 +6,7 @@
 use super::allocator::{KVmalloc, Kmalloc, Vmalloc};
 use super::{AllocError, Allocator, Flags};
 use core::alloc::Layout;
+use core::borrow::{Borrow, BorrowMut};
 use core::fmt;
 use core::marker::PhantomData;
 use core::mem::ManuallyDrop;
@@ -504,6 +505,62 @@ where
     }
 }
 
+/// # Examples
+///
+/// ```
+/// # use core::borrow::Borrow;
+/// # use kernel::alloc::KBox;
+/// struct Foo<B: Borrow<u32>>(B);
+///
+/// // Owned instance.
+/// let owned = Foo(1);
+///
+/// // Owned instance using `KBox`.
+/// let owned_kbox = Foo(KBox::new(1, GFP_KERNEL)?);
+///
+/// let i = 1;
+/// // Borrowed from `i`.
+/// let borrowed = Foo(&i);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> Borrow<T> for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn borrow(&self) -> &T {
+        self.deref()
+    }
+}
+
+/// # Examples
+///
+/// ```
+/// # use core::borrow::BorrowMut;
+/// # use kernel::alloc::KBox;
+/// struct Foo<B: BorrowMut<u32>>(B);
+///
+/// // Owned instance.
+/// let owned = Foo(1);
+///
+/// // Owned instance using `KBox`.
+/// let owned_kbox = Foo(KBox::new(1, GFP_KERNEL)?);
+///
+/// let mut i = 1;
+/// // Borrowed from `i`.
+/// let borrowed = Foo(&mut i);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> BorrowMut<T> for Box<T, A>
+where
+    T: ?Sized,
+    A: Allocator,
+{
+    fn borrow_mut(&mut self) -> &mut T {
+        self.deref_mut()
+    }
+}
+
 impl<T, A> fmt::Display for Box<T, A>
 where
     T: ?Sized + fmt::Display,
diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
index 0477041cbc03..3c72e0bdddb8 100644
--- a/rust/kernel/alloc/kvec.rs
+++ b/rust/kernel/alloc/kvec.rs
@@ -8,6 +8,7 @@ use super::{
     AllocError, Allocator, Box, Flags,
 };
 use core::{
+    borrow::{Borrow, BorrowMut},
     fmt,
     marker::PhantomData,
     mem::{ManuallyDrop, MaybeUninit},
@@ -851,7 +852,7 @@ where
     }
 }
 
-impl<T> Default for KVec<T> {
+impl<T, A: Allocator> Default for Vec<T, A> {
     #[inline]
     fn default() -> Self {
         Self::new()
@@ -890,6 +891,58 @@ where
     }
 }
 
+/// # Examples
+///
+/// ```
+/// # use core::borrow::Borrow;
+/// struct Foo<B: Borrow<[u32]>>(B);
+///
+/// // Owned array.
+/// let owned_array = Foo([1, 2, 3]);
+///
+/// // Owned vector.
+/// let owned_vec = Foo(KVec::from_elem(0, 3, GFP_KERNEL)?);
+///
+/// let arr = [1, 2, 3];
+/// // Borrowed slice from `arr`.
+/// let borrowed_slice = Foo(&arr[..]);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> Borrow<[T]> for Vec<T, A>
+where
+    A: Allocator,
+{
+    fn borrow(&self) -> &[T] {
+        self.as_slice()
+    }
+}
+
+/// # Examples
+///
+/// ```
+/// # use core::borrow::BorrowMut;
+/// struct Foo<B: BorrowMut<[u32]>>(B);
+///
+/// // Owned array.
+/// let owned_array = Foo([1, 2, 3]);
+///
+/// // Owned vector.
+/// let owned_vec = Foo(KVec::from_elem(0, 3, GFP_KERNEL)?);
+///
+/// let mut arr = [1, 2, 3];
+/// // Borrowed slice from `arr`.
+/// let borrowed_slice = Foo(&mut arr[..]);
+/// # Ok::<(), Error>(())
+/// ```
+impl<T, A> BorrowMut<[T]> for Vec<T, A>
+where
+    A: Allocator,
+{
+    fn borrow_mut(&mut self) -> &mut [T] {
+        self.as_mut_slice()
+    }
+}
+
 impl<T: Eq, A> Eq for Vec<T, A> where A: Allocator {}
 
 impl<T, I: SliceIndex<[T]>, A> Index<I> for Vec<T, A>