commit 580cc37b1de4fcd9997c48d7080e744533f09f36 upstream.

The functions `[Pin]Init::__[pinned_]init` and `ptr::write` called from
the `init!` macro require the passed pointer to be aligned. This fact is
ensured by the creation of field accessors to previously initialized
fields.

Since we missed this very important fact from the beginning [1],
document it in the code.

Link: https://rust-for-linux.zulipchat.com/#narrow/channel/561532-pin-init/topic/initialized.20field.20accessor.20detection/with/576210658 [1]
Fixes: 90e53c5e70a6 ("rust: add pin-init API core")
Cc: <stable@vger.kernel.org> # 6.6.y, 6.12.y: 42415d163e5d: rust: pin-init: add references to previously initialized fields
Cc: <stable@vger.kernel.org> # 6.6.y, 6.12.y, 6.18.y, 6.19.y
Signed-off-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260302140424.4097655-2-lossin@kernel.org
[ Updated Cc: stable@ tags as discussed. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
[ Moved changes to the declarative macro, because 6.19.y and earlier do not
  have `syn`. Also duplicated the comment for all field accessor creations.
  - Benno ]
Signed-off-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit a58b8764aed9648357b1c5b6368c9943ba33b7f9 ]

`clippy` has changed behavior in [1] (Rust 1.95) where it no longer
warns about the `let_and_return` lint when a comment is placed between
the let binding and the return expression. Nightly thus fails to build,
because the expectation is no longer fulfilled.

Thus replace the expectation with an `allow`.

[ The errors were:

      error: this lint expectation is unfulfilled
          --> rust/pin-init/src/lib.rs:1279:10
           |
      1279 | #[expect(clippy::let_and_return)]
           |          ^^^^^^^^^^^^^^^^^^^^^^
           |
           = note: `-D unfulfilled-lint-expectations` implied by `-D warnings`
           = help: to override `-D warnings` add `#[allow(unfulfilled_lint_expectations)]`

      error: this lint expectation is unfulfilled
          --> rust/pin-init/src/lib.rs:1295:10
           |
      1295 | #[expect(clippy::let_and_return)]
           |          ^^^^^^^^^^^^^^^^^^^^^^

    - Miguel ]

Link: https://github.com/rust-lang/rust-clippy/pull/16461 [1]
Signed-off-by: Benno Lossin <lossin@kernel.org>
Cc: stable@vger.kernel.org # Needed in 6.18.y and later.
Link: https://patch.msgid.link/20260215132232.1549861-1-lossin@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

After initializing a field in an initializer macro, create a variable
holding a reference that points at that field. The type is either
`Pin<&mut T>` or `&mut T` depending on the field's structural pinning
kind.

[ Applied fixes to devres and rust_driver_pci sample - Benno]
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Benno Lossin <lossin@kernel.org>

Allow writing `_: { /* any number of statements */ }` in initializers to
run arbitrary code during initialization.

    try_init!(MyStruct {
        _: {
            if check_something() {
                return Err(MyError);
            }
        },
        foo: Foo::new(val),
        _: {
            println!("successfully initialized `MyStruct`");
        },
    })

Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Benno Lossin <lossin@kernel.org>

Make the `#[pin_data]` macro generate a `*Projection` struct that holds
either `Pin<&mut Field>` or `&mut Field` for every field of the original
struct. Which version is chosen depends on weather there is a `#[pin]`
or not respectively. Access to this projected version is enabled through
generating `fn project(self: Pin<&mut Self>) -> SelfProjection<'_>`.

[ Adapt workqueue to use the new projection instead of its own, custom
  one - Benno ]

Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Benno Lossin <lossin@kernel.org>

The next commit makes the `#[pin_data]` attribute generate a `project`
function that would collide with any existing ones.

Signed-off-by: Benno Lossin <lossin@kernel.org>

Signed-off-by: Benno Lossin <lossin@kernel.org>

When running this example with no cargo features enabled, the compiler
warns on 1.89:

  error: struct `Error` is never constructed
    --> examples/error.rs:11:12
     |
  11 | pub struct Error;
     |            ^^^^^
     |
     = note: `-D dead-code` implied by `-D warnings`
     = help: to override `-D warnings` add `#[allow(dead_code)]`

Thus use the error in the main function to avoid this warning.

Signed-off-by: Benno Lossin <lossin@kernel.org>

Pull pin-init updates from Benno Lossin:
 "Added:

   - 'impl<T, E> [Pin]Init<T, E> for Result<T, E>', so results are now
     (pin-)initializers.

   - 'Zeroable::init_zeroed()' delegating to 'init_zeroed()'.

   - New 'zeroed()', a safe version of 'mem::zeroed()' and also provide
     it via 'Zeroable::zeroed()'.

   - Implement 'Zeroable' for 'Option<&T>' and 'Option<&mut T>'.

   - Implement 'Zeroable' for 'Option<[unsafe] [extern "abi"]
     fn(...args...) -> ret>' for '"Rust"' and '"C"' ABIs and up to 20
     arguments.

  Changed:

   - Blanket impls of 'Init' and 'PinInit' from 'impl<T, E>
     [Pin]Init<T, E> for T' to 'impl<T> [Pin]Init<T> for T'.

   - Renamed 'zeroed()' to 'init_zeroed()'.

  Upstream dev news:

   - More CI improvements to deny warnings, use '--all-targets'. Also
     check the synchronization status of the two '-next' branches in
     upstream and the kernel."

Acked-by: Andreas Hindborg <a.hindborg@kernel.org>

* tag 'pin-init-v6.17' of https://github.com/Rust-for-Linux/linux:
  rust: pin-init: examples, tests: use `ignore` instead of conditionally compiling tests
  rust: init: remove doctest's `Error::from_errno` workaround
  rust: init: re-enable doctests
  rust: pin-init: implement `ZeroableOption` for function pointers with up to 20 arguments
  rust: pin-init: change `impl Zeroable for Option<NonNull<T>>` to `ZeroableOption for NonNull<T>`
  rust: pin-init: implement `ZeroableOption` for `&T` and `&mut T`
  rust: pin-init: add `zeroed()` & `Zeroable::zeroed()` functions
  rust: pin-init: add `Zeroable::init_zeroed`
  rust: pin-init: rename `zeroed` to `init_zeroed`
  rust: pin-init: feature-gate the `stack_init_reuse` test on the `std` feature
  rust: pin-init: examples: pthread_mutex: disable the main test for miri
  rust: pin-init: examples, tests: add conditional compilation in order to compile under any feature combination
  rust: pin-init: change blanket impls for `[Pin]Init` and add one for `Result<T, E>`
  rust: pin-init: improve safety documentation for `impl<T> [Pin]Init<T> for T`

Use a consistent `# Examples` heading in rustdoc across the codebase.

Some modules previously used `## Examples` (even when they should be
available as top-level headers), while others used `# Example`, which
deviates from the preferred `# Examples` style.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Benno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/ddd5ce0ac20c99a72a4f1e4322d3de3911056922.1749545815.git.viresh.kumar@linaro.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>