bybrooklyn/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-04-18 14:53:58 -04:00
Code Issues Packages Projects Releases Wiki Activity

rust: retain pointer mut-ness in container_of!

Browse Source 
Avoid casting the input pointer to `*const _`, allowing the output
pointer to be `*mut` if the input is `*mut`. This allows a number of
`*const` to `*mut` conversions to be removed at the cost of slightly
worse ergonomics when the macro is used with a reference rather than a
pointer; the only example of this was in the macro's own doctest.

Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250409-container-of-mutness-v1-1-64f472b94534@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Tamir Duberstein
2025-04-09 10:43:16 -04:00
committed by Miguel Ojeda
parent a3b2347343
commit 74d6a606c2
2 changed files with 12 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
rust/kernel/lib.rs
View File

@@ -205,7 +205,7 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
/// }
///
/// let test = Test { a: 10, b: 20 };
/// let b_ptr = &test.b;
/// let b_ptr: *const _ = &test.b;
/// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be
/// // in-bounds of the same allocation as `b_ptr`.
/// let test_alias = unsafe { container_of!(b_ptr, Test, b) };
@@ -214,9 +214,8 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
#[macro_export]
macro_rules! container_of {
($ptr:expr, $type:ty, $($f:tt)*) => {{
let ptr = $ptr as *const _ as *const u8;
let offset: usize = ::core::mem::offset_of!($type, $($f)*);
ptr.sub(offset) as *const $type
$ptr.byte_sub(offset).cast::<$type>()
}}
}