| Message ID | 20240805152004.5039-3-dakr@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Generic `Allocator` support for Rust | expand |
On 05.08.24 17:19, Danilo Krummrich wrote: > 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@google.com> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > --- > rust/kernel/alloc/allocator.rs | 27 ++++++++++++++++++--------- > 1 file changed, 18 insertions(+), 9 deletions(-) > > diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs > index e6ea601f38c6..e7b7eba84acb 100644 > --- a/rust/kernel/alloc/allocator.rs > +++ b/rust/kernel/alloc/allocator.rs > @@ -8,27 +8,36 @@ > > struct KernelAllocator; > > -/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. > -/// > -/// # Safety > -/// > -/// - `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 { > +/// 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). > - let size = layout.size(); > + layout.size() > +} > > +/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. > +/// > +/// # Safety > +/// > +/// - `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 { > // SAFETY: > // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the > // function safety requirement. > // - `size` is greater than 0 since it's from `layout.size()` (which cannot be zero according > // to the function safety requirement) > - unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 } > + unsafe { > + bindings::krealloc( > + ptr as *const core::ffi::c_void, > + aligned_size(new_layout), Can you move the safe operation outside of the `unsafe` block? With that changed, Reviewed-by: Benno Lossin <benno.lossin@proton.me> --- Cheers, Benno > + flags.0, > + ) as *mut u8 > + } > } > > unsafe impl GlobalAlloc for KernelAllocator { > -- > 2.45.2 >
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index e6ea601f38c6..e7b7eba84acb 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -8,27 +8,36 @@ struct KernelAllocator; -/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. -/// -/// # Safety -/// -/// - `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 { +/// 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). - let size = layout.size(); + layout.size() +} +/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. +/// +/// # Safety +/// +/// - `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 { // SAFETY: // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the // function safety requirement. // - `size` is greater than 0 since it's from `layout.size()` (which cannot be zero according // to the function safety requirement) - unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 } + unsafe { + bindings::krealloc( + ptr as *const core::ffi::c_void, + aligned_size(new_layout), + flags.0, + ) as *mut u8 + } } unsafe impl GlobalAlloc for KernelAllocator {