The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x df27cef153603b18a7d094b53cc3d5264ff32797 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025031635-resent-sniff-676f@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From df27cef153603b18a7d094b53cc3d5264ff32797 Mon Sep 17 00:00:00 2001 From: Benno Lossin benno.lossin@proton.me Date: Wed, 5 Mar 2025 13:29:01 +0000 Subject: [PATCH] rust: init: fix `Zeroable` implementation for `Option<NonNull<T>>` and `Option<KBox<T>>`
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] Reported-by: Alice Ryhl aliceryhl@google.com Closes: https://lore.kernel.org/rust-for-linux/CAH5fLghL+qzrD8KiCF1V3vf2YcC6aWySzkma... 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 Reviewed-by: Alice Ryhl aliceryhl@google.com Reviewed-by: Andreas Hindborg a.hindborg@kernel.org Link: https://lore.kernel.org/r/20250305132836.2145476-1-benno.lossin@proton.me [ Added Closes tag and moved up the Reported-by one. - Miguel ] Signed-off-by: Miguel Ojeda ojeda@kernel.org
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. //