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2026-01-17rust: pin-init: internal: init: simplify Zeroable safety checkBenno Lossin-6/+1
The `Zeroable` type check uses a small dance with a raw pointer to aid type inference. It turns out that this is not necessary and type inference is powerful enough to resolve any ambiguity. Thus remove it. Suggested-by: Gary Guo <gary@garyguo.net> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: internal: init: add escape hatch for referencing initialized ↵Benno Lossin-23/+52
fields The initializer macro emits mutable references for already initialized fields, which allows modifying or accessing them later in code blocks or when initializing other fields. This behavior results in compiler errors when combining with packed structs, since those do not permit creating references to misaligned fields. For example: #[repr(C, packed)] struct Foo { a: i8, b: i32, } fn main() { let _ = init!(Foo { a: -42, b: 42 }); } This will lead to an error like this: error[E0793]: reference to field of packed struct is unaligned --> tests/ui/compile-fail/init/packed_struct.rs:10:13 | 10 | let _ = init!(Foo { a: -42, b: 42 }); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: this struct is 1-byte aligned, but the type of this field may require higher alignment = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) = note: this error originates in the macro `init` (in Nightly builds, run with -Z macro-backtrace for more info) This was requested by Janne Grunau [1] and will most certainly be used by the kernel when we eventually end up with trying to initialize packed structs. Thus add an initializer attribute `#[disable_initialized_field_access]` that does what the name suggests: do not generate references to already initialized fields. There is space for future work: add yet another attribute which can be applied on fields of initializers that ask for said field to be made accessible. We can add that when the need arises. Requested-by: Janne Grunau <j@jannau.net> Link: https://lore.kernel.org/all/20251206170214.GE1097212@robin.jannau.net [1] Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: internal: init: add support for attributes on initializer fieldsBenno Lossin-14/+55
Initializer fields ought to support the same attributes that are allowed in struct initializers on fields. For example, `cfg` or lint levels such as `expect`, `allow` etc. Add parsing support for these attributes using syn to initializer fields and adjust the macro expansion accordingly. Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: add `#[default_error(<type>)]` attribute to initializer macrosBenno Lossin-3/+41
The `#[default_error(<type>)]` attribute can be used to supply a default type as the error used for the `[pin_]init!` macros. This way one can easily define custom `try_[pin_]init!` variants that default to your project specific error type. Just write the following declarative macro: macro_rules! try_init { ($($args:tt)*) => { ::pin_init::init!( #[default_error(YourCustomErrorType)] $($args)* ) } } Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: rewrite the initializer macros using `syn`Benno Lossin-0/+458
Rewrite the initializer macros `[pin_]init!` using `syn`. No functional changes intended aside from improved error messages on syntactic and semantical errors. For example if one forgets to use `<-` with an initializer (and instead uses `:`): impl Bar { fn new() -> impl PinInit<Self> { ... } } impl Foo { fn new() -> impl PinInit<Self> { pin_init!(Self { bar: Bar::new() }) } } Then the declarative macro would report: error[E0308]: mismatched types --> tests/ui/compile-fail/init/colon_instead_of_arrow.rs:21:9 | 14 | fn new() -> impl PinInit<Self> { | ------------------ the found opaque type ... 21 | pin_init!(Self { bar: Bar::new() }) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | | | expected `Bar`, found opaque type | arguments to this function are incorrect | = note: expected struct `Bar` found opaque type `impl pin_init::PinInit<Bar>` note: function defined here --> $RUST/core/src/ptr/mod.rs | | pub const unsafe fn write<T>(dst: *mut T, src: T) { | ^^^^^ = note: this error originates in the macro `$crate::__init_internal` which comes from the expansion of the macro `pin_init` (in Nightly builds, run with -Z macro-backtrace for more info) And the new error is: error[E0308]: mismatched types --> tests/ui/compile-fail/init/colon_instead_of_arrow.rs:21:31 | 14 | fn new() -> impl PinInit<Self> { | ------------------ the found opaque type ... 21 | pin_init!(Self { bar: Bar::new() }) | --- ^^^^^^^^^^ expected `Bar`, found opaque type | | | arguments to this function are incorrect | = note: expected struct `Bar` found opaque type `impl pin_init::PinInit<Bar>` note: function defined here --> $RUST/core/src/ptr/mod.rs | | pub const unsafe fn write<T>(dst: *mut T, src: T) { | ^^^^^ Importantly, this error gives much more accurate span locations, pointing to the offending field, rather than the entire macro invocation. Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: add `?Sized` bounds to traits in `#[pin_data]` macroBenno Lossin-2/+2
The `#[pin_data]` macro uses some auxiliary traits to ensure that a user does not implement `Drop` for the annotated struct, as that is unsound and can lead to UB. However, if the struct that is annotated is `!Sized`, the current bounds do not work, because `Sized` is an implicit bound for generics. This is *not* a soundness hole of pin-init, as it currently is impossible to construct an unsized struct using pin-init. Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: rewrite `#[pin_data]` using `syn`Benno Lossin-264/+503
Rewrite the attribute macro `#[pin_data]` using `syn`. No functional changes intended aside from improved error messages on syntactic and semantical errors. For example if one forgets a comma at the end of a field: #[pin_data] struct Foo { a: Box<Foo> b: Box<Foo> } The declarative macro reports the following errors: error: expected `,`, or `}`, found `b` --> tests/ui/compile-fail/pin_data/missing_comma.rs:5:16 | 5 | a: Box<Foo> | ^ help: try adding a comma: `,` error: recursion limit reached while expanding `$crate::__pin_data!` --> tests/ui/compile-fail/pin_data/missing_comma.rs:3:1 | 3 | #[pin_data] | ^^^^^^^^^^^ | = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`$CRATE`) = note: this error originates in the macro `$crate::__pin_data` which comes from the expansion of the attribute macro `pin_data` (in Nightly builds, run with -Z macro-backtrace for more info) The new `syn` version reports: error: expected `,`, or `}`, found `b` --> tests/ui/compile-fail/pin_data/missing_comma.rs:5:16 | 5 | a: Box<Foo> | ^ help: try adding a comma: `,` error: expected `,` --> tests/ui/compile-fail/pin_data/missing_comma.rs:6:5 | 6 | b: Box<Foo> | ^ Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: rewrite the `#[pinned_drop]` attribute macro using `syn`Benno Lossin-38/+52
Rewrite the attribute macro for implementing `PinnedDrop` using `syn`. Otherwise no functional changes intended aside from improved error messages on syntactic and semantical errors. For example: When missing the `drop` function in the implementation, the old error was: error: no rules expected `)` --> tests/ui/compile-fail/pinned_drop/no_fn.rs:6:1 | 6 | #[pinned_drop] | ^^^^^^^^^^^^^^ no rules expected this token in macro call | note: while trying to match keyword `fn` --> src/macros.rs | | fn drop($($sig:tt)*) { | ^^ = note: this error originates in the attribute macro `pinned_drop` (in Nightly builds, run with -Z macro-backtrace for more info) And the new one is: error[E0046]: not all trait items implemented, missing: `drop` --> tests/ui/compile-fail/pinned_drop/no_fn.rs:7:1 | 7 | impl PinnedDrop for Foo {} | ^^^^^^^^^^^^^^^^^^^^^^^ missing `drop` in implementation | = help: implement the missing item: `fn drop(self: Pin<&mut Self>, _: OnlyCallFromDrop) { todo!() }` Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: rewrite `derive(Zeroable)` and `derive(MaybeZeroable)` using ↵Benno Lossin-92/+74
`syn` Rewrite the two derive macros for `Zeroable` using `syn`. One positive side effect of this change is that tuple structs are now supported by them. Additionally, syntax errors and the error emitted when trying to use one of the derive macros on an `enum` are improved. Otherwise no functional changes intended. For example: #[derive(Zeroable)] enum Num { A(u32), B(i32), } Produced this error before this commit: error: no rules expected keyword `enum` --> tests/ui/compile-fail/zeroable/enum.rs:5:1 | 5 | enum Num { | ^^^^ no rules expected this token in macro call | note: while trying to match keyword `struct` --> src/macros.rs | | $vis:vis struct $name:ident | ^^^^^^ Now the error is: error: cannot derive `Zeroable` for an enum --> tests/ui/compile-fail/zeroable/enum.rs:5:1 | 5 | enum Num { | ^^^^ error: cannot derive `Zeroable` for an enum Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: internal: add utility API for syn error handlingBenno Lossin-0/+33
The API is similar to diagnostics handling in rustc and uses a `ErrorGuaranteed` value to signify that an error has been emitted. It supports both fatal errors (which abort the macro expansion immediately by returning `Err(ErrorGuaranteed)`) and non-fatal ones at generation time. These errors are appended to the token stream after generation has finished normally. This allows giving good errors while still expanding most of the code as expected to avoid the user encountering additional errors (for example missing definitions). Suggested-by: Gary Guo <gary@garyguo.net> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> [ remove duplicate word in commit message - Benno ] Signed-off-by: Benno Lossin <lossin@kernel.org>
2026-01-17rust: pin-init: add `syn` dependency and remove `proc-macro[2]` and `quote` ↵Benno Lossin-43/+14
workarounds `syn` makes parsing Rust from proc-macros a lot simpler. `pin-init` has not used `syn` up until now, because the we did not support it. That changed in commit 54e3eae85562 ("Merge patch series "`syn` support""), so we can finally utilize the added ergonomics of parsing proc-macro input with `syn`. Previously we only had the `proc-macro` library available, whereas the user-space version also used `proc-macro2` and `quote`. Now both are available, so remove the workarounds. Due to these changes, clippy emits warnings about unnecessary `.to_string()` as `proc-macro2` provides an additional `PartialEq` impl on `Ident`, so the warnings are fixed. [ Adjusted wording from upstream version and added build system changes for the kernel - Benno ] Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Reviewed-by: Tamir Duberstein <tamird@gmail.com> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Signed-off-by: Benno Lossin <lossin@kernel.org>
2025-05-18Merge tag 'pin-init-v6.16' of https://github.com/Rust-for-Linux/linux into ↵Miguel Ojeda-1/+32
rust-next Pull pin-init updates from Benno Lossin: "Added: - 'Wrapper<T>' trait for creating pin-initializers for wrapper structs with a structurally pinned value such as 'UnsafeCell<T>' or 'MaybeUninit<T>'. - 'MaybeZeroable' derive macro to try to derive 'Zeroable', but not error if not all fields implement it. This is needed to derive 'Zeroable' for all bindgen-generated structs. - 'unsafe fn cast_[pin_]init()' functions to unsafely change the initialized type of an initializer. These are utilized by the 'Wrapper<T>' implementations. Changed: - Added support for visibility in 'Zeroable' derive macro. - Added support for 'union's in 'Zeroable' derive macro. Upstream dev news: - The CI has been streamlined & some bugs with it have been fixed. I also added new workflows to check if the user-space version and the one in the kernel tree have diverged. - I also started to use the issues [1] tab to keep track of any problems or unexpected/unwanted things. This should help folks report and diagnose issues w.r.t. 'pin-init' better. [1] https://github.com/rust-for-linux/pin-init/issues" * tag 'pin-init-v6.16' of https://github.com/Rust-for-Linux/linux: rust: pin-init: improve documentation for `Zeroable` derive macros rust: pin-init: fix typos rust: pin-init: add `MaybeZeroable` derive macro rust: pin-init: allow `Zeroable` derive macro to also be applied to unions rust: pin-init: allow `pub` fields in `derive(Zeroable)` rust: pin-init: Update the structural pinning link in readme. rust: pin-init: Update Changelog and Readme rust: pin-init: Implement `Wrapper` for `UnsafePinned` behind feature flag. rust: pin-init: Add the `Wrapper` trait. rust: pin-init: add `cast_[pin_]init` functions to change the initialized type rust: pin-init: examples: use `allow` instead of `expect` rust: pin-init: examples: conditionally enable `feature(lint_reasons)` rust: pin-init: internal: skip rustfmt formatting of kernel-only module rust: pin-init: synchronize README.md
2025-05-07rust: clean Rust 1.88.0's `clippy::uninlined_format_args` lintMiguel Ojeda-2/+1
Starting with Rust 1.88.0 (expected 2025-06-26) [1], `rustc` may move back the `uninlined_format_args` to `style` from `pedantic` (it was there waiting for rust-analyzer suppotr), and thus we will start to see lints like: warning: variables can be used directly in the `format!` string --> rust/macros/kunit.rs:105:37 | 105 | let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 105 - let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); 105 + let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{test}"); There is even a case that is a pure removal: warning: variables can be used directly in the `format!` string --> rust/macros/module.rs:51:13 | 51 | format!("{field}={content}\0", field = field, content = content) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 51 - format!("{field}={content}\0", field = field, content = content) 51 + format!("{field}={content}\0") The lints all seem like nice cleanups, thus just apply them. We may want to disable `allow-mixed-uninlined-format-args` in the future. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust-clippy/pull/14160 [1] Acked-by: Benno Lossin <lossin@kernel.org> Reviewed-by: Tamir Duberstein <tamird@gmail.com> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250502140237.1659624-6-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-01rust: pin-init: add `MaybeZeroable` derive macroBenno Lossin-1/+31
This derive macro implements `Zeroable` for structs & unions precisely if all fields also implement `Zeroable` and does nothing otherwise. The plain `Zeroable` derive macro instead errors when it cannot derive `Zeroable` safely. The `MaybeZeroable` derive macro is useful in cases where manual checking is infeasible such as with the bindings crate. Move the zeroable generics parsing into a standalone function in order to avoid code duplication between the two derive macros. Link: https://github.com/Rust-for-Linux/pin-init/pull/42/commits/1165cdad1a391b923efaf30cf76bc61e38da022e Signed-off-by: Benno Lossin <benno.lossin@proton.me>
2025-04-21rust: pin-init: internal: skip rustfmt formatting of kernel-only moduleBenno Lossin-0/+1
The `quote` module only is available in the kernel and thus running `cargo fmt` or `rustfmt internal/src/lib.rs` in the user-space repository [1] results in: error: couldn't read `~/pin-init/internal/src/../../../macros/quote.rs`: No such file or directory (os error 2) --> ~/pin-init/internal/src/lib.rs:25:1 | 25 | mod quote; | ^^^^^^^^^^ Error writing files: failed to resolve mod `quote`: ~/pin-init/internal/src/../../../macros/quote.rs does not exist Thus mark it with `rustfmt::skip` when compiling without kernel support. Link: https://github.com/Rust-for-Linux/pin-init [1] Link: https://github.com/Rust-for-Linux/pin-init/pull/33/commits/a6caf1945e51da38761aab4dffa56e63e2baa218 Link: https://lore.kernel.org/all/20250414195928.129040-2-benno.lossin@proton.me Reviewed-by: Christian Schrefl <chrisi.schrefl@gmail.com> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
2025-03-16rust: pin-init: miscellaneous synchronization with the user-space versionBenno Lossin-3/+2
Remove the last differences between the kernel version and the user-space version. Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Fiona Behrens <me@kloenk.dev> Link: https://lore.kernel.org/r/20250308110339.2997091-20-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16rust: pin-init: internal: synchronize with user-space versionBenno Lossin-3/+25
Synchronize the internal macros crate with the user-space version that uses the quote crate [1] instead of a custom `quote!` macro. The imports in the different version are achieved using `cfg` on the kernel config value. This cfg is always set in the kernel and never set in the user-space version. Since the quote crate requires the proc_macro2 crate, imports also need to be adjusted and `.into()` calls have to be inserted. Link: https://crates.io/crates/quote [1] Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Fiona Behrens <me@Kloenk.dev> Link: https://lore.kernel.org/r/20250308110339.2997091-19-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16rust: make pin-init its own crateBenno Lossin-11/+26
Rename relative paths inside of the crate to still refer to the same items, also rename paths inside of the kernel crate and adjust the build system to build the crate. [ Remove the `expect` (and thus the `lint_reasons` feature) since the tree now uses `quote!` from `rust/macros/export.rs`. Remove the `TokenStream` import removal, since it is now used as well. In addition, temporarily (i.e. just for this commit) use an `--extern force:alloc` to prevent an unknown `new_uninit` error in the `rustdoc` target. For context, please see a similar case in: https://lore.kernel.org/lkml/20240422090644.525520-1-ojeda@kernel.org/ And adjusted the message above. - Miguel ] Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Fiona Behrens <me@kloenk.dev> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20250308110339.2997091-16-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16rust: add pin-init crate build infrastructureMiguel Ojeda-0/+7
Add infrastructure for moving the initialization API to its own crate. Covers all make targets such as `rust-analyzer` and `rustdoc`. The tests of pin-init are not added to `rusttest`, as they are already tested in the user-space repository [1]. Link: https://github.com/Rust-for-Linux/pin-init [1] Co-developed-by: Benno Lossin <benno.lossin@proton.me> Signed-off-by: Benno Lossin <benno.lossin@proton.me> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20250308110339.2997091-15-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16rust: pin-init: move proc-macro documentation into pin-init crateBenno Lossin-106/+3
Move the documentation of proc-macros from pin-init-internal into pin-init. This is because documentation can only reference types from dependencies and pin-init-internal cannot have pin-init as a dependency, as that would be cyclic. Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Fiona Behrens <me@kloenk.dev> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20250308110339.2997091-5-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-16rust: move pin-init API into its own directoryBenno Lossin-0/+520
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 <benno.lossin@proton.me> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org> Reviewed-by: Fiona Behrens <me@kloenk.dev> Tested-by: Andreas Hindborg <a.hindborg@kernel.org> Link: https://lore.kernel.org/r/20250308110339.2997091-3-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>