[PATCH 11/14] rust: make `Arc::into_unique_or_drop` associated function

Boqun Feng
2025-09-05T04:42:11Z

From: Gary Guo <gary@garyguo.net>

Make `Arc::into_unique_or_drop` to become a mere associated function
instead of a method (i.e. removing the `self` receiver).

It's a general convention for Rust smart pointers to avoid having
methods defined on them, because if the pointee type has a method of the
same name, then it is shadowed. This is normally for avoiding semver
breakage, which isn't an issue for kernel codebase, but it's still
generally a good practice to follow this rule, so that `ptr.foo()` would
always be calling a method on the pointee type.

Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250723233312.3304339-3-gary@kernel.org
---
rust/kernel/sync/arc.rs | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 63a66761d0c7..4ee155b43b2d 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -321,7 +321,7 @@ pub fn ptr_eq(this: &Self, other: &Self) -> bool {
/// use kernel::sync::{Arc, UniqueArc};
///
/// let arc = Arc::new(42, GFP_KERNEL)?;
- /// let unique_arc = arc.into_unique_or_drop();
+ /// let unique_arc = Arc::into_unique_or_drop(arc);
///
/// // The above conversion should succeed since refcount of `arc` is 1.
/// assert!(unique_arc.is_some());
@@ -337,18 +337,18 @@ pub fn ptr_eq(this: &Self, other: &Self) -> bool {
/// let arc = Arc::new(42, GFP_KERNEL)?;
/// let another = arc.clone();
///
- /// let unique_arc = arc.into_unique_or_drop();
+ /// let unique_arc = Arc::into_unique_or_drop(arc);
///
/// // The above conversion should fail since refcount of `arc` is >1.
/// assert!(unique_arc.is_none());
///
/// # Ok::<(), Error>(())
/// ```
- pub fn into_unique_or_drop(self) -> Option<Pin<UniqueArc<T>>> {
+ pub fn into_unique_or_drop(this: Self) -> Option<Pin<UniqueArc<T>>> {
// We will manually manage the refcount in this method, so we disable the destructor.
- let me = ManuallyDrop::new(self);
+ let this = ManuallyDrop::new(this);
// SAFETY: We own a refcount, so the pointer is still valid.
- let refcount = unsafe { me.ptr.as_ref() }.refcount.get();
+ let refcount = unsafe { this.ptr.as_ref() }.refcount.get();

// If the refcount reaches a non-zero value, then we have destroyed this `Arc` and will
// return without further touching the `Arc`. If the refcount reaches zero, then there are
@@ -365,7 +365,7 @@ pub fn into_unique_or_drop(self) -> Option<Pin<UniqueArc<T>>> {
// must pin the `UniqueArc` because the values was previously in an `Arc`, and they pin
// their values.
Some(Pin::from(UniqueArc {
- inner: ManuallyDrop::into_inner(me),
+ inner: ManuallyDrop::into_inner(this),
}))
} else {
None
--
2.51.0