rust: enable `clippy::ref_as_ptr` lint

In Rust 1.78.0, Clippy introduced the `ref_as_ptr` lint [1]:

> Using `as` casts may result in silently changing mutability or type.

While this doesn't eliminate unchecked `as` conversions, it makes such
conversions easier to scrutinize.  It also has the slight benefit of
removing a degree of freedom on which to bikeshed. Thus apply the
changes and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ref_as_ptr
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/all/D8PGG7NTWB6U.3SS3A5LN4XWMN@proton.me/
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-6-f43b024581e8@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/Makefile b/Makefile
index a95000adf2613e0cd1b49168010e76ed81d54b8a..31268acb0d22bed6734807f71f0c399d436b23a6 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -489,6 +489,7 @@ export rust_common_flags := --edition=2021 \
                            -Wclippy::no_mangle_with_rust_abi \
                            -Wclippy::ptr_as_ptr \
                            -Wclippy::ptr_cast_constness \
+                           -Wclippy::ref_as_ptr \
                            -Wclippy::undocumented_unsafe_blocks \
                            -Wclippy::unnecessary_safety_comment \
                            -Wclippy::unnecessary_safety_doc \

diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs
index 7631c9f6708d56ef6ca136c4d20ea5180ba937e0..474cc98c48a323216933521bd3981cfd814a2e28 100644 (file)
--- a/rust/bindings/lib.rs
+++ b/rust/bindings/lib.rs
@@ -27,6 +27,7 @@
 #[allow(dead_code)]
 #[allow(clippy::cast_lossless)]
 #[allow(clippy::ptr_as_ptr)]
+#[allow(clippy::ref_as_ptr)]
 #[allow(clippy::undocumented_unsafe_blocks)]
 #[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]
 mod bindings_raw {

diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs
index bc8e15dcec181dc0b6e5cf6a0b6e4db60c2b6263..1ddac786bd0dd953185d044e2409bad0a9aab0a5 100644 (file)
--- a/rust/kernel/configfs.rs
+++ b/rust/kernel/configfs.rs
@@ -426,7 +426,7 @@ where
     };
 
     const fn vtable_ptr() -> *const bindings::configfs_group_operations {
-        &Self::VTABLE as *const bindings::configfs_group_operations
+        &Self::VTABLE
     }
 }
 
@@ -464,7 +464,7 @@ where
     };
 
     const fn vtable_ptr() -> *const bindings::configfs_item_operations {
-        &Self::VTABLE as *const bindings::configfs_item_operations
+        &Self::VTABLE
     }
 }
 
@@ -476,7 +476,7 @@ impl<Data> ItemOperationsVTable<Subsystem<Data>, Data> {
     };
 
     const fn vtable_ptr() -> *const bindings::configfs_item_operations {
-        &Self::VTABLE as *const bindings::configfs_item_operations
+        &Self::VTABLE
     }
 }
 
@@ -717,11 +717,7 @@ impl<const N: usize, Data> AttributeList<N, Data> {
 
         // SAFETY: By function safety requirements, we have exclusive access to
         // `self` and the reference created below will be exclusive.
-        unsafe {
-            (&mut *self.0.get())[I] = (attribute as *const Attribute<ID, O, Data>)
-                .cast_mut()
-                .cast()
-        };
+        unsafe { (&mut *self.0.get())[I] = core::ptr::from_ref(attribute).cast_mut().cast() };
     }
 }
 
@@ -761,9 +757,7 @@ macro_rules! impl_item_type {
                         ct_owner: owner.as_ptr(),
                         ct_group_ops: GroupOperationsVTable::<Data, Child>::vtable_ptr().cast_mut(),
                         ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(),
-                        ct_attrs: (attributes as *const AttributeList<N, Data>)
-                            .cast_mut()
-                            .cast(),
+                        ct_attrs: core::ptr::from_ref(attributes).cast_mut().cast(),
                         ct_bin_attrs: core::ptr::null_mut(),
                     }),
                     _p: PhantomData,
@@ -780,9 +774,7 @@ macro_rules! impl_item_type {
                         ct_owner: owner.as_ptr(),
                         ct_group_ops: core::ptr::null_mut(),
                         ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(),
-                        ct_attrs: (attributes as *const AttributeList<N, Data>)
-                            .cast_mut()
-                            .cast(),
+                        ct_attrs: core::ptr::from_ref(attributes).cast_mut().cast(),
                         ct_bin_attrs: core::ptr::null_mut(),
                     }),
                     _p: PhantomData,

diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
index f9d55ac7b9e67e8493445ab5059caf04ce50b34f..3dc72ca8cfc263ed420b75cac95e172572d426f2 100644 (file)
--- a/rust/kernel/device_id.rs
+++ b/rust/kernel/device_id.rs
@@ -136,7 +136,7 @@ impl<T: RawDeviceId, U, const N: usize> IdTable<T, U> for IdArray<T, U, N> {
     fn as_ptr(&self) -> *const T::RawType {
         // This cannot be `self.ids.as_ptr()`, as the return pointer must have correct provenance
         // to access the sentinel.
-        (self as *const Self).cast()
+        core::ptr::from_ref(self).cast()
     }
 
     fn id(&self, index: usize) -> &T::RawType {

diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs
index e9bfbad0075538b4d3d841421e04fa6c17f516a2..35fd5db35c465279acb3b88dc3c90c8f95d29cf4 100644 (file)
--- a/rust/kernel/fs/file.rs
+++ b/rust/kernel/fs/file.rs
@@ -366,7 +366,7 @@ impl core::ops::Deref for File {
         //
         // By the type invariants, there are no `fdget_pos` calls that did not take the
         // `f_pos_lock` mutex.
-        unsafe { LocalFile::from_raw_file((self as *const Self).cast()) }
+        unsafe { LocalFile::from_raw_file(core::ptr::from_ref(self).cast()) }
     }
 }
 

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 43597eb7c5c1a7518a4185c40fe45558e2528d28..cbc8b459ed4162602048a669e4a9a3da8dcd562c 100644 (file)
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -29,7 +29,7 @@ impl BStr {
     #[inline]
     pub const fn from_bytes(bytes: &[u8]) -> &Self {
         // SAFETY: `BStr` is transparent to `[u8]`.
-        unsafe { &*(bytes as *const [u8] as *const BStr) }
+        unsafe { &*(core::ptr::from_ref(bytes) as *const BStr) }
     }
 
     /// Strip a prefix from `self`. Delegates to [`slice::strip_prefix`].
@@ -290,7 +290,7 @@ impl CStr {
     #[inline]
     pub unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut CStr {
         // SAFETY: Properties of `bytes` guaranteed by the safety precondition.
-        unsafe { &mut *(bytes as *mut [u8] as *mut CStr) }
+        unsafe { &mut *(core::ptr::from_mut(bytes) as *mut CStr) }
     }
 
     /// Returns a C pointer to the string.

diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index 6d70edd8086a9f1ce38f78d312d6a7cfc03141a1..4ef13cf13a78ffe389236c180f6dac0ff9af2dee 100644 (file)
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -240,7 +240,7 @@ impl UserSliceReader {
     pub fn read_slice(&mut self, out: &mut [u8]) -> Result {
         // SAFETY: The types are compatible and `read_raw` doesn't write uninitialized bytes to
         // `out`.
-        let out = unsafe { &mut *(out as *mut [u8] as *mut [MaybeUninit<u8>]) };
+        let out = unsafe { &mut *(core::ptr::from_mut(out) as *mut [MaybeUninit<u8>]) };
         self.read_raw(out)
     }
 
@@ -355,7 +355,7 @@ impl UserSliceWriter {
         let res = unsafe {
             bindings::_copy_to_user(
                 self.ptr as *mut c_void,
-                (value as *const T).cast::<c_void>(),
+                core::ptr::from_ref(value).cast::<c_void>(),
                 len,
             )
         };

diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs
index 08e68ebef6062561e27c0f0ca158dd5c0687a439..31c2f713313fe3cc0cf090e74bd3b569b54ddd38 100644 (file)
--- a/rust/uapi/lib.rs
+++ b/rust/uapi/lib.rs
@@ -16,6 +16,7 @@
     clippy::all,
     clippy::cast_lossless,
     clippy::ptr_as_ptr,
+    clippy::ref_as_ptr,
     clippy::undocumented_unsafe_blocks,
     dead_code,
     missing_docs,