kernel/linux.git/rust/pin-init/src/__internal.rs, branch v7.0-rc7

rust: pin-init: replace shadowed return token by `unsafe`-to-create token

2026-03-12T07:46:17+00:00

We use a unit struct `__InitOk` in the closure generated by the initializer macros as the return value. We shadow it by creating a struct with the same name again inside of the closure, preventing early returns of `Ok` in the initializer (before all fields have been initialized). In the face of Type Alias Impl Trait (TAIT) and the next trait solver, this solution no longer works [1]. The shadowed struct can be named through type inference. In addition, there is an RFC proposing to add the feature of path inference to Rust, which would similarly allow [2]. Thus remove the shadowed token and replace it with an `unsafe` to create token. The reason we initially used the shadowing solution was because an alternative solution used a builder pattern. Gary writes [3]: In the early builder-pattern based InitOk, having a single InitOk type for token is unsound because one can launder an InitOk token used for one place to another initializer. I used a branded lifetime solution, and then you figured out that using a shadowed type would work better because nobody could construct it at all. The laundering issue does not apply to the approach we ended up with today. With this change, the example by Tim Chirananthavat in [1] no longer compiles and results in this error: error: cannot construct `pin_init::__internal::InitOk` with struct literal syntax due to private fields --> src/main.rs:26:17 | 26 | InferredType {} | ^^^^^^^^^^^^ | = note: private field `0` that was not provided help: you might have meant to use the `new` associated function | 26 - InferredType {} 26 + InferredType::new() | Applying the suggestion of using the `::new()` function, results in another expected error: error[E0133]: call to unsafe function `pin_init::__internal::InitOk::new` is unsafe and requires unsafe block --> src/main.rs:26:17 | 26 | InferredType::new() | ^^^^^^^^^^^^^^^^^^^ call to unsafe function | = note: consult the function's documentation for information on how to avoid undefined behavior Reported-by: Tim Chirananthavat Link: https://github.com/rust-lang/rust/issues/153535 [1] Link: https://github.com/rust-lang/rfcs/pull/3444#issuecomment-4016145373 [2] Link: https://github.com/rust-lang/rust/issues/153535#issuecomment-4017620804 [3] Fixes: fc6c6baa1f40 ("rust: init: add initialization macros") Cc: stable@vger.kernel.org Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260311105056.1425041-1-lossin@kernel.org [ Added period as mentioned. - Miguel ] Signed-off-by: Miguel Ojeda

rust: pin-init: feature-gate the `stack_init_reuse` test on the `std` feature

2025-06-11T19:13:56+00:00

When trying to run `cargo check --all-targets --no-default-features`, an error is reported by the test, as it cannot find the `std` crate. This is to be expected, since the `--no-default-features` flag enables the `no-std` behavior of the crate. Thus exclude the test in that scenario. Link: https://github.com/Rust-for-Linux/pin-init/pull/50/commits/2813729ccacdedee9dbfcab1ed285b8721a0391b Link: https://lore.kernel.org/all/20250523125424.192843-4-lossin@kernel.org [ Changed my author email address to @kernel.org. - Benno ] Signed-off-by: Benno Lossin

rust: pin-init: miscellaneous synchronization with the user-space version

2025-03-16T20:59:19+00:00

Remove the last differences between the kernel version and the user-space version. Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Tested-by: Andreas Hindborg Reviewed-by: Fiona Behrens Link: https://lore.kernel.org/r/20250308110339.2997091-20-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: pin-init: synchronize documentation with the user-space version

2025-03-16T20:59:19+00:00

Synchronize documentation and examples with the user-space version. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Reviewed-by: Andreas Hindborg Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-18-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: pin-init: add `std` and `alloc` support from the user-space version

2025-03-16T20:59:19+00:00

To synchronize the kernel's version of pin-init with the user-space version, introduce support for `std` and `alloc`. While the kernel uses neither, the user-space version has to support both. Thus include the required `#[cfg]`s and additional code. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-17-benno.lossin@proton.me [ Undo the temporary `--extern force:alloc` since now we have contents for `alloc` here. - Miguel ] Signed-off-by: Miguel Ojeda

rust: pin-init: remove kernel-crate dependency

2025-03-16T20:59:19+00:00

In order to make pin-init a standalone crate, remove dependencies on kernel-specific code such as `ScopeGuard` and `KBox`. `ScopeGuard` is only used in the `[pin_]init_array_from_fn` functions and can easily be replaced by a primitive construct. `KBox` is only used for type variance of unsized types and can also easily be replaced. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Reviewed-by: Andreas Hindborg Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-13-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: pin-init: fix documentation links

2025-03-16T20:59:19+00:00

Before switching to compile the `pin-init` crate directly, change any links that would be invalid to links that are valid both before and after the switch. Signed-off-by: Benno Lossin Reviewed-by: Fiona Behrens Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-12-benno.lossin@proton.me Signed-off-by: Miguel Ojeda

rust: move pin-init API into its own directory

2025-03-16T20:59:18+00:00

In preparation of splitting off the pin-init crate from the kernel crate, move all pin-init API code (including proc-macros) into `rust/pin-init`. Moved modules have their import path adjusted via the `#[path = "..."]` attribute. This allows the files to still be imported in the kernel crate even though the files are in different directories. Code that is moved out of files (but the file itself stays where it is) is imported via the `include!` macro. This also allows the code to be moved while still being part of the kernel crate. Note that this commit moves the generics parsing code out of the GPL-2.0 file `rust/macros/helpers.rs` into the Apache-2.0 OR MIT file `rust/pin_init/internal/src/helpers.rs`. I am the sole author of that code and it already is available with that license at [1]. The same is true for the entry-points of the proc-macros `pin_data`, `pinned_drop` and `derive_zeroable` in `rust/macros/lib.rs` that are moved to `rust/pin_data/internal/src/lib.rs`. Although there are some smaller patches that fix the doctests. Link: https://github.com/Rust-for-Linux/pinned-init [1] Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Fiona Behrens Tested-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250308110339.2997091-3-benno.lossin@proton.me Signed-off-by: Miguel Ojeda