On Thu, Apr 17, 2025 at 12:48 PM Boqun Feng boqun.feng@gmail.com wrote:
On Wed, Apr 16, 2025 at 01:36:05PM -0400, Tamir Duberstein wrote:
In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]:
Though `as` casts between raw pointers are not terrible, `pointer::cast` is safer because it cannot accidentally change the pointer's mutability, nor cast the pointer to other types like `usize`.
There are a few classes of changes required:
- Modules generated by bindgen are marked `#[allow(clippy::ptr_as_ptr)]`.
- Inferred casts (` as _`) are replaced with `.cast()`.
- Ascribed casts (` as *... T`) are replaced with `.cast::<T>()`.
- Multistep casts from references (` as *const _ as *const T`) are replaced with `core::ptr::from_ref(&x).cast()` with or without `::<T>` according to the previous rules. The `core::ptr::from_ref` call is required because `(x as *const _).cast::<T>()` results in inference failure.
- Native literal C strings are replaced with `c_str!().as_char_ptr()`.
- `*mut *mut T as _` is replaced with `let *mut *const T = (*mut *mut T)`.cast();` since pointer to pointer can be confusing.
Apply these changes and enable the lint -- no functional change intended.
Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr [1] Reviewed-by: Benno Lossin benno.lossin@proton.me Signed-off-by: Tamir Duberstein tamird@gmail.com
Reviewed-by: Boqun Feng boqun.feng@gmail.com
Thanks!
A few nits below though...
Makefile | 1 + rust/bindings/lib.rs | 1 + rust/kernel/alloc/allocator_test.rs | 2 +- rust/kernel/alloc/kvec.rs | 4 ++-- rust/kernel/device.rs | 4 ++-- rust/kernel/devres.rs | 2 +- rust/kernel/dma.rs | 4 ++-- rust/kernel/error.rs | 2 +- rust/kernel/firmware.rs | 3 ++- rust/kernel/fs/file.rs | 2 +- rust/kernel/kunit.rs | 11 +++++++---- rust/kernel/list/impl_list_item_mod.rs | 2 +- rust/kernel/pci.rs | 2 +- rust/kernel/platform.rs | 4 +++- rust/kernel/print.rs | 6 +++--- rust/kernel/seq_file.rs | 2 +- rust/kernel/str.rs | 2 +- rust/kernel/sync/poll.rs | 2 +- rust/kernel/time/hrtimer/pin.rs | 2 +- rust/kernel/time/hrtimer/pin_mut.rs | 2 +- rust/kernel/workqueue.rs | 10 +++++----- rust/uapi/lib.rs | 1 + 22 files changed, 40 insertions(+), 31 deletions(-)
[...]
diff --git a/rust/kernel/list/impl_list_item_mod.rs b/rust/kernel/list/impl_list_item_mod.rs index a0438537cee1..1f9498c1458f 100644 --- a/rust/kernel/list/impl_list_item_mod.rs +++ b/rust/kernel/list/impl_list_item_mod.rs @@ -34,7 +34,7 @@ pub unsafe trait HasListLinks<const ID: u64 = 0> { unsafe fn raw_get_list_links(ptr: *mut Self) -> *mut ListLinks<ID> { // SAFETY: The caller promises that the pointer is valid. The implementer promises that the // `OFFSET` constant is correct.
unsafe { (ptr as *mut u8).add(Self::OFFSET) as *mut ListLinks<ID> }
unsafe { ptr.cast::<u8>().add(Self::OFFSET).cast() }I think we better do:
unsafe { ptr.byte_add(Self::OFFSET).cast() }here, similar for a few instances below. Maybe in a follow-up patch? byte_add() is way more clear about what is done here.
This code is deleted in https://lore.kernel.org/all/20250409-list-no-offset-v2-4-0bab7e3c9fd8@gmail...., which could also use a review!
Cheers. Tamir