diff options
author | Wedson Almeida Filho <wedsonaf@gmail.com> | 2024-02-19 12:48:08 +0100 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2024-02-25 19:17:31 +0100 |
commit | e944171070b65521c0513c01c56174ec8fd7d249 (patch) | |
tree | dbd917cf6917f54f77f3a816153bddc20bdc5b8a /rust | |
parent | rust: str: implement `Display` and `Debug` for `BStr` (diff) | |
download | linux-e944171070b65521c0513c01c56174ec8fd7d249.tar.xz linux-e944171070b65521c0513c01c56174ec8fd7d249.zip |
rust: add `container_of!` macro
This macro is used to obtain a pointer to an entire struct
when given a pointer to a field in that struct.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Link: https://lore.kernel.org/r/20240219-b4-rbtree-v2-1-0b113aab330d@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r-- | rust/kernel/lib.rs | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 1e5f229b8263..be68d5e567b1 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -101,3 +101,35 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { // SAFETY: FFI call. unsafe { bindings::BUG() }; } + +/// Produces a pointer to an object from a pointer to one of its fields. +/// +/// # Safety +/// +/// The pointer passed to this macro, and the pointer returned by this macro, must both be in +/// bounds of the same allocation. +/// +/// # Examples +/// +/// ``` +/// # use kernel::container_of; +/// struct Test { +/// a: u64, +/// b: u32, +/// } +/// +/// let test = Test { a: 10, b: 20 }; +/// let b_ptr = &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) }; +/// assert!(core::ptr::eq(&test, test_alias)); +/// ``` +#[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 + }} +} |