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Message-ID: <20240812182355.11641-3-dakr@kernel.org>
Date: Mon, 12 Aug 2024 20:22:48 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: ojeda@...nel.org,
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Cc: daniel.almeida@...labora.com,
faith.ekstrand@...labora.com,
boris.brezillon@...labora.com,
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Danilo Krummrich <dakr@...nel.org>
Subject: [PATCH v5 02/26] rust: alloc: separate `aligned_size` from `krealloc_aligned`
Separate `aligned_size` from `krealloc_aligned`.
Subsequent patches implement `Allocator` derivates, such as `Kmalloc`,
that require `aligned_size` and replace the original `krealloc_aligned`.
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
Reviewed-by: Benno Lossin <benno.lossin@...ton.me>
Signed-off-by: Danilo Krummrich <dakr@...nel.org>
---
rust/kernel/alloc/allocator.rs | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index e6ea601f38c6..c83b6dff896d 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -8,6 +8,17 @@
struct KernelAllocator;
+/// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment.
+fn aligned_size(new_layout: Layout) -> usize {
+ // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
+ let layout = new_layout.pad_to_align();
+
+ // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`
+ // which together with the slab guarantees means the `krealloc` will return a properly aligned
+ // object (see comments in `kmalloc()` for more information).
+ layout.size()
+}
+
/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.
///
/// # Safety
@@ -15,13 +26,7 @@
/// - `ptr` can be either null or a pointer which has been allocated by this allocator.
/// - `new_layout` must have a non-zero size.
pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
- // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
- let layout = new_layout.pad_to_align();
-
- // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`
- // which together with the slab guarantees means the `krealloc` will return a properly aligned
- // object (see comments in `kmalloc()` for more information).
- let size = layout.size();
+ let size = aligned_size(new_layout);
// SAFETY:
// - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
--
2.45.2
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