Messages in this thread | | | Date | Fri, 31 Mar 2023 21:51:15 +0000 | From | y86-dev@protonma ... | Subject | [PATCH v4 00/15] Rust pin-init API for pinned initialization of structs |
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From: Benno Lossin <y86-dev@protonmail.com>
This is the fourth version of the pin-init API. See [1] for v3.
The tree at [2] contains these patches applied on top of 6.3-rc1. The Rust-doc documentation of the pin-init API can be found at [3].
These patches are a long way coming, since I held a presentation on safe pinned initialization at Kangrejos [4]. And my discovery of this problem was almost a year ago [5].
- #1 enables the `pin_macro` feature which is already stable in Rust version 1.68. - #2 adds a utility macro `quote!` for proc-macros. This macro converts the typed characters directly into Rust tokens that are the output of proc-macros. It is used by the pin-init API proc-macros. - #3 changes the `Err` types of the constructor functions of `Arc` and `UniqueArc` to `AllocError`. - #4 adds the `assume_init` function to `UniqueArc<MaybeUninit<T>>` that unsafely assumes the pointee to be initialized and returns a `UniqueArc<T>`. `UniqueArc::write` is modified to use this new function. Later patches use it as well. - #5 adds `Opaque::raw_get` to access the value inside of an `Opaque` from a raw pointer only. - #6-11 introduce the pin-init API. The commit message of #4 details the problem it solves and lays out the overall architecture. The implementation details are fairly complex; however, this is required to provide a safe API for users -- reducing the amount of `unsafe` code is a key goal of the Rust support in the kernel. An example of the before/after difference from the point of view of users is provided in the commit message. It is a goal to at some point have pin-init as a language feature of Rust. A first step in this direction is the Field Projection RFC [6]. - #12 adds important traits and macros from pin-init to the prelude. - #13 adds functions for easier initialization of `Opaque<T>` via FFI and raw pointer initializer functions. This is necessary when writing Rust wrappers and will be used by Wedson's `sync` module patches. - #14 improves the `UniqueArc::try_new_uninit` function by using the pin-init API. The old version first allocated uninitialized memory on the stack and then moved it into the location in the heap. The new version directly allocates this on the heap. - #15 adds functions for initializing already allocated `UniqueArc`s, this will be used by the Android Binder driver.
--
Changelog:
v3 -> v4: - Improve documentation. - Fixing doc-tests imports, comments and full paths in macro examples. - Implement `Zeroable` for many more types. - Fix unsoundness: `Zeroable` allowed to create fat pointers with a null VTABLE pointer. - Split fallible components from `stack_pin_init!` into `stack_try_pin_init!`. - Move `Invariant` type alias and `InitClosure` into `__internal`. - Change the error type of the constructor functions of `Arc` and `UniqueArc` to `AllocError`. - Add `try` variants to `InPlaceInit` to allow custom error types. - Make `StackInit::init` a safe function. - Rename `OnlyCallFromDrop::create` to `OnlyCallFromDrop::new`. - Enable the `pin_macro` feature for use inside of `stack_pin_init!`. - Make `quote!` and `quote_spanned!` use absolute paths.
v2 -> v3: - Split the big original commit into six smaller commits. - Use `PinnedDrop` in the `RawFoo` code example. - Move the `init::common::ffi_init` functions to `Opaque::ffi_init`. - Move all `#[doc(hidden)]`, internal types into the new `__internal` module. - Specify safety guarantees and requirements of the initializer macros. - Add a detailed example of what the expanded code of the various macros looks like. - Require generics in the initializer macros to use turbofish syntax (`::<>`). - Refactor the internals of the initializer macros, this way they have better type inference and generic arguments can be omitted more often. - Replace `init::from_value` with a blanket impl of the initializer traits for ordinary objects. - Add initializing functions for already allocated `UniqueArc`s. - Add `Opaque::manual_init` functions akin to `ffi_init`, but they take an `extern "Rust" fn` instead. - Documentation and inline comment improvements.
v1 -> v2: - Split the common module and `UniqueArc::assume_init` into their own commits. - Change the generics syntax of `pin_init!` to reflect normal struct generic syntax. - Replace `PinnedDrop::__ensure_no_unsafe_op_in_drop` with an only unsafely creatable token. - Hide `StackInit<T>` in the docs, because it is internal API. - Improve macro internals of `pin_init!` according to Gary's review. - Add check for `PhantomPinned` fields without a `#[pin]` attribute in `#[pin_data]`, as those fields will not have the intended effect. - Add docs to `quote.rs`.
[1] https://lore.kernel.org/rust-for-linux/20230329223239.138757-1-y86-dev@protonmail.com/ [2] https://github.com/y86-dev/linux.git patch/pinned-init-v4 [3] https://rust-for-linux.github.io/docs/pinned-init/kernel/init [4] https://kangrejos.com [5] https://github.com/Rust-for-Linux/linux/issues/772 [6] https://github.com/rust-lang/rfcs/pull/3318
Benno Lossin (14): rust: enable the `pin_macro` feature rust: sync: change error type of constructor functions rust: sync: add `assume_init` to `UniqueArc` rust: types: add `Opaque::raw_get` rust: add pin-init API core rust: init: add initialization macros rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers rust: init: add `PinnedDrop` trait and macros rust: init: add `stack_pin_init!` macro rust: init: add `Zeroable` trait and `init::zeroed` function rust: prelude: add `pin-init` API items to prelude rust: types: add common init-helper functions for `Opaque` rust: sync: reduce stack usage of `UniqueArc::try_new_uninit` rust: sync: add functions for initializing `UniqueArc<MaybeUninit<T>>`
Gary Guo (1): rust: macros: add `quote!` macro
rust/kernel/init.rs | 1429 ++++++++++++++++++++++++++++++++ rust/kernel/init/__internal.rs | 234 ++++++ rust/kernel/init/macros.rs | 971 ++++++++++++++++++++++ rust/kernel/lib.rs | 7 + rust/kernel/prelude.rs | 6 +- rust/kernel/sync/arc.rs | 80 +- rust/kernel/types.rs | 55 ++ rust/macros/lib.rs | 80 ++ rust/macros/pin_data.rs | 79 ++ rust/macros/pinned_drop.rs | 49 ++ rust/macros/quote.rs | 143 ++++ scripts/Makefile.build | 2 +- 12 files changed, 3127 insertions(+), 8 deletions(-) create mode 100644 rust/kernel/init.rs create mode 100644 rust/kernel/init/__internal.rs create mode 100644 rust/kernel/init/macros.rs create mode 100644 rust/macros/pin_data.rs create mode 100644 rust/macros/pinned_drop.rs create mode 100644 rust/macros/quote.rs
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6 -- 2.39.2
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