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 a reference-to-pointer coercion + `(*const Self).cast()`.
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 | 5 +++-- 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile index ec8efc8e23ba..c62bae2b107b 100644 --- a/Makefile +++ b/Makefile @@ -484,6 +484,7 @@ 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 7943f43b9575..10c6d69be7f3 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. @@ -151,11 +151,12 @@ pub(crate) unsafe fn wrapper_ptr(this: *mut Self) -> NonNull<RequestDataWrapper> /// Return a reference to the [`RequestDataWrapper`] stored in the private /// area of the request structure. pub(crate) fn wrapper_ref(&self) -> &RequestDataWrapper { + let this: *const _ = self; // SAFETY: By type invariant, `self.0` is a valid allocation. Further, // 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(this.cast_mut()).as_ref() } } }