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| author | Miguel Ojeda <ojeda@kernel.org> | 2025-04-07 20:18:21 +0000 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2025-04-08 21:12:58 +0200 |
| commit | 3c75fff196c35c3bbe8c212ad03db94994130b32 (patch) | |
| tree | 514c144e26796918e43925b4f68699f7583ed00e /rust/pin-init/src | |
| parent | 05a2b0011c4b6cbbc9b577f6abebe4e9333b0cf6 (diff) | |
| download | linux-3c75fff196c35c3bbe8c212ad03db94994130b32.tar.gz linux-3c75fff196c35c3bbe8c212ad03db94994130b32.tar.bz2 linux-3c75fff196c35c3bbe8c212ad03db94994130b32.zip | |
rust: pin-init: alloc: restrict `impl ZeroableOption` for `Box` to `T: Sized`
Similar to what was done for `Zeroable<NonNull<T>>` in commit
df27cef15360 ("rust: init: fix `Zeroable` implementation for
`Option<NonNull<T>>` and `Option<KBox<T>>`"), the latest Rust
documentation [1] says it guarantees that `transmute::<_,
Option<T>>([0u8; size_of::<T>()])` is sound and produces
`Option::<T>::None` only in some cases. In particular, it says:
`Box<U>` (specifically, only `Box<U, Global>`) when `U: Sized`
Thus restrict the `impl` to `Sized`, and use similar wording as in that
commit too.
Link: https://doc.rust-lang.org/stable/std/option/index.html#representation [1]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/pin-init/pull/32/commits/a6007cf555e5946bcbfafe93a6468c329078acd8
Fixes: 9b2299af3b92 ("rust: pin-init: add `std` and `alloc` support from the user-space version")
Cc: stable@vger.kernel.org
[ Adjust mentioned commit to the one from the kernel. - Benno ]
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250407201755.649153-2-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust/pin-init/src')
| -rw-r--r-- | rust/pin-init/src/alloc.rs | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/rust/pin-init/src/alloc.rs b/rust/pin-init/src/alloc.rs index e16baa3b434e..5017f57442d8 100644 --- a/rust/pin-init/src/alloc.rs +++ b/rust/pin-init/src/alloc.rs @@ -17,11 +17,9 @@ use crate::{ pub extern crate alloc; -// 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 and there -// is no problem with a VTABLE pointer being null. -unsafe impl<T: ?Sized> ZeroableOption for Box<T> {} +// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee: +// <https://doc.rust-lang.org/stable/std/option/index.html#representation>). +unsafe impl<T> ZeroableOption for Box<T> {} /// Smart pointer that can initialize memory in-place. pub trait InPlaceInit<T>: Sized { |