On Wed, Apr 16, 2025 at 01:36:06PM -0400, Tamir Duberstein wrote:
In Rust 1.72.0, Clippy introduced the `ptr_cast_constness` lint [1]:
Though `as` casts between raw pointers are not terrible, `pointer::cast_mut` and `pointer::cast_const` are safer because they cannot accidentally cast the pointer to another type.
There are only 2 affected sites:
- `*mut T as *const U as *mut U` becomes `(*mut T).cast()`
- `&self as *const Self as *mut Self` becomes `core::ptr::from_ref(self).cast_mut()`.
Apply these changes and enable the lint -- no functional change intended.
Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_cast_constness [1] Reviewed-by: Benno Lossin benno.lossin@proton.me Signed-off-by: Tamir Duberstein tamird@gmail.com
Makefile | 1 + rust/kernel/block/mq/request.rs | 4 ++-- rust/kernel/dma.rs | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/Makefile b/Makefile index 5d2931344490..7b85b2a8d371 100644 --- a/Makefile +++ b/Makefile @@ -481,6 +481,7 @@ export rust_common_flags := --edition=2021 \ -Aclippy::needless_lifetimes \ -Wclippy::no_mangle_with_rust_abi \ -Wclippy::ptr_as_ptr \
-Wclippy::ptr_cast_constness \ -Wclippy::undocumented_unsafe_blocks \ -Wclippy::unnecessary_safety_comment \ -Wclippy::unnecessary_safety_doc \diff --git a/rust/kernel/block/mq/request.rs b/rust/kernel/block/mq/request.rs index 4a5b7ec914ef..af5c9ac94f36 100644 --- a/rust/kernel/block/mq/request.rs +++ b/rust/kernel/block/mq/request.rs @@ -69,7 +69,7 @@ pub(crate) unsafe fn aref_from_raw(ptr: *mut bindings::request) -> ARef<Self> { // INVARIANT: By the safety requirements of this function, invariants are upheld. // SAFETY: By the safety requirement of this function, we own a // reference count that we can pass to `ARef`.
unsafe { ARef::from_raw(NonNull::new_unchecked(ptr as *const Self as *mut Self)) }
unsafe { ARef::from_raw(NonNull::new_unchecked(ptr.cast())) }/// Notify the block layer that a request is going to be processed now. @@ -155,7 +155,7 @@ pub(crate) fn wrapper_ref(&self) -> &RequestDataWrapper { // the private data associated with this request is initialized and // valid. The existence of `&self` guarantees that the private data is // valid as a shared reference.
unsafe { Self::wrapper_ptr(self as *const Self as *mut Self).as_ref() }
unsafe { Self::wrapper_ptr(core::ptr::from_ref(self).cast_mut()).as_ref() }} diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs index f395d1a6fe48..43ecf3c2e860 100644 --- a/rust/kernel/dma.rs +++ b/rust/kernel/dma.rs @@ -186,7 +186,7 @@ pub fn alloc_attrs( dev: dev.into(), dma_handle, count,
cpu_addr: ret.cast(),
cpu_addr: ret.cast::<T>(),
Is this change necessary? The rest looks good to me.
Regards, Boqun
dma_attrs, }) }-- 2.49.0