From 3c75fff196c35c3bbe8c212ad03db94994130b32 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 7 Apr 2025 20:18:21 +0000 Subject: rust: pin-init: alloc: restrict `impl ZeroableOption` for `Box` to `T: Sized` Similar to what was done for `Zeroable>` in commit df27cef15360 ("rust: init: fix `Zeroable` implementation for `Option>` and `Option>`"), the latest Rust documentation [1] says it guarantees that `transmute::<_, Option>([0u8; size_of::()])` is sound and produces `Option::::None` only in some cases. In particular, it says: `Box` (specifically, only `Box`) 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 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 Link: https://lore.kernel.org/r/20250407201755.649153-2-benno.lossin@proton.me Signed-off-by: Miguel Ojeda --- rust/pin-init/src/alloc.rs | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'rust/pin-init/src') 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 ZeroableOption for Box {} +// SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee: +// ). +unsafe impl ZeroableOption for Box {} /// Smart pointer that can initialize memory in-place. pub trait InPlaceInit: Sized { -- cgit v1.2.3 From 193b5a75744af2669ad7c5f7aa4f9219dc73ca69 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 7 Apr 2025 20:18:29 +0000 Subject: rust: pin-init: use Markdown autolinks in Rust comments "Normal" comments in Rust (`//`) are also formatted in Markdown, like the documentation (`///` and `//!`), see Documentation/rust/coding-guidelines.rst Thus use Markdown autolinks for a couple links that were missing it. It also helps to get proper linking in some software like kitty [1]. Suggested-by: Benno Lossin Link: https://github.com/Rust-for-Linux/pin-init/pull/32#discussion_r2023103712 [1] Signed-off-by: Miguel Ojeda Link: https://github.com/Rust-for-Linux/pin-init/pull/32/commits/dd230d61bf0538281072fbff4bb71efc58f3420c Fixes: 84837cf6fa54 ("rust: pin-init: change examples to the user-space version") Cc: stable@vger.kernel.org [ Change case in title. Reworded commit message. - Benno ] Signed-off-by: Benno Lossin Link: https://lore.kernel.org/r/20250407201755.649153-3-benno.lossin@proton.me Signed-off-by: Miguel Ojeda --- rust/pin-init/src/lib.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/pin-init/src') diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs index 05c44514765e..0806c689f693 100644 --- a/rust/pin-init/src/lib.rs +++ b/rust/pin-init/src/lib.rs @@ -1447,7 +1447,7 @@ impl_zeroable! { {} UnsafeCell, // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee: - // https://doc.rust-lang.org/stable/std/option/index.html#representation). + // ). Option, Option, Option, Option, Option, Option, Option, Option, Option, Option, -- cgit v1.2.3