[PATCH v12 2/6] rust: enable `clippy::ptr_cast_constness` lint
From: Tamir Duberstein <hidden>
Date: 2025-06-15 20:55:16
Also in:
dri-devel, linux-block, linux-devicetree, linux-kbuild, linux-kselftest, linux-mm, linux-pci, linux-pm, lkml, nouveau, rust-for-linux
Subsystem:
block layer device driver api [rust], drm drivers, drm drivers and common infrastructure [rust], kernel build + files below scripts/ (unless maintained elsewhere), rust, the rest · Maintainers:
Andreas Hindborg, David Airlie, Simona Vetter, Danilo Krummrich, Alice Ryhl, Nathan Chancellor, Nicolas Schier, Miguel Ojeda, Linus Torvalds
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 3 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()`. - `*const T as *mut _` becommes `(*const T).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 <redacted> Reviewed-by: Boqun Feng <redacted> Signed-off-by: Tamir Duberstein <redacted> --- Makefile | 1 + rust/kernel/block/mq/request.rs | 4 ++-- rust/kernel/drm/device.rs | 4 ++-- 3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 21cc6e312ec9..5eeddfbf5900 100644
--- a/Makefile
+++ b/Makefile@@ -485,6 +485,7 @@ 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/drm/device.rs b/rust/kernel/drm/device.rs
index 624d7a4c83ea..ef66deb7ce23 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs@@ -83,8 +83,8 @@ impl<T: drm::Driver> Device<T> { major: T::INFO.major, minor: T::INFO.minor, patchlevel: T::INFO.patchlevel, - name: T::INFO.name.as_char_ptr() as *mut _, - desc: T::INFO.desc.as_char_ptr() as *mut _, + name: T::INFO.name.as_char_ptr().cast_mut(), + desc: T::INFO.desc.as_char_ptr().cast_mut(), driver_features: drm::driver::FEAT_GEM, ioctls: T::IOCTLS.as_ptr(),
--
2.49.0