According to [1], `NonNull<T>` and `#[repr(transparent)]` wrapper types such as our custom `KBox<T>` have the null pointer optimization only if `T: Sized`. Thus remove the `Zeroable` implementation for the unsized case.

Link: https://doc.rust-lang.org/stable/std/option/index.html#representation [1] Cc: stable@vger.kernel.org # v6.12+ (a custom patch will be needed for 6.6.y) Fixes: 38cde0bd7b67 ("rust: init: add `Zeroable` trait and `init::zeroed` function") Signed-off-by: Benno Lossin benno.lossin@proton.me --- rust/kernel/init.rs | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 7fd1ea8265a5..8bbd5e3398fc 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -1418,17 +1418,14 @@ macro_rules! impl_zeroable { // SAFETY: `T: Zeroable` and `UnsafeCell` is `repr(transparent)`. {<T: ?Sized + Zeroable>} UnsafeCell<T>,

- // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee). + // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee: + // https://doc.rust-lang.org/stable/std/option/index.html#representation). Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>, Option<NonZeroU128>, Option<NonZeroUsize>, Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>, Option<NonZeroI128>, Option<NonZeroIsize>, - - // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee). - // - // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant. - {<T: ?Sized>} Option<NonNull<T>>, - {<T: ?Sized>} Option<KBox<T>>, + {<T>} Option<NonNull<T>>, + {<T>} Option<KBox<T>>,

// SAFETY: `null` pointer is valid. //

base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6