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2025-03-13rust: start using the `#[expect(...)]` attributeMiguel Ojeda
commit 1f9ed172545687e5c04c77490a45896be6d2e459 upstream. In Rust, it is possible to `allow` particular warnings (diagnostics, lints) locally, making the compiler ignore instances of a given warning within a given function, module, block, etc. It is similar to `#pragma GCC diagnostic push` + `ignored` + `pop` in C: #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wunused-function" static void f(void) {} #pragma GCC diagnostic pop But way less verbose: #[allow(dead_code)] fn f() {} By that virtue, it makes it possible to comfortably enable more diagnostics by default (i.e. outside `W=` levels) that may have some false positives but that are otherwise quite useful to keep enabled to catch potential mistakes. The `#[expect(...)]` attribute [1] takes this further, and makes the compiler warn if the diagnostic was _not_ produced. For instance, the following will ensure that, when `f()` is called somewhere, we will have to remove the attribute: #[expect(dead_code)] fn f() {} If we do not, we get a warning from the compiler: warning: this lint expectation is unfulfilled --> x.rs:3:10 | 3 | #[expect(dead_code)] | ^^^^^^^^^ | = note: `#[warn(unfulfilled_lint_expectations)]` on by default This means that `expect`s do not get forgotten when they are not needed. See the next commit for more details, nuances on its usage and documentation on the feature. The attribute requires the `lint_reasons` [2] unstable feature, but it is becoming stable in 1.81.0 (to be released on 2024-09-05) and it has already been useful to clean things up in this patch series, finding cases where the `allow`s should not have been there. Thus, enable `lint_reasons` and convert some of our `allow`s to `expect`s where possible. This feature was also an example of the ongoing collaboration between Rust and the kernel -- we tested it in the kernel early on and found an issue that was quickly resolved [3]. Cc: Fridtjof Stoldt <xfrednet@gmail.com> Cc: Urgau <urgau@numericable.fr> Link: https://rust-lang.github.io/rfcs/2383-lint-reasons.html#expect-lint-attribute [1] Link: https://github.com/rust-lang/rust/issues/54503 [2] Link: https://github.com/rust-lang/rust/issues/114557 [3] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Trevor Gross <tmgross@umich.edu> Tested-by: Gary Guo <gary@garyguo.net> Reviewed-by: Gary Guo <gary@garyguo.net> Link: https://lore.kernel.org/r/20240904204347.168520-18-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-03-13rust: replace `clippy::dbg_macro` with `disallowed_macros`Miguel Ojeda
commit 8577c9dca799bd74377f7c30015d8cdc53a53ca2 upstream. Back when we used Rust 1.60.0 (before Rust was merged in the kernel), we added `-Wclippy::dbg_macro` to the compilation flags. This worked great with our custom `dbg!` macro (vendored from `std`, but slightly modified to use the kernel printing facilities). However, in the very next version, 1.61.0, it stopped working [1] since the lint started to use a Rust diagnostic item rather than a path to find the `dbg!` macro [1]. This behavior remains until the current nightly (1.83.0). Therefore, currently, the `dbg_macro` is not doing anything, which explains why we can invoke `dbg!` in samples/rust/rust_print.rs`, as well as why changing the `#[allow()]`s to `#[expect()]`s in `std_vendor.rs` doctests does not work since they are not fulfilled. One possible workaround is using `rustc_attrs` like the standard library does. However, this is intended to be internal, and we just started supporting several Rust compiler versions, so it is best to avoid it. Therefore, instead, use `disallowed_macros`. It is a stable lint and is more flexible (in that we can provide different macros), although its diagnostic message(s) are not as nice as the specialized one (yet), and does not allow to set different lint levels per macro/path [2]. In turn, this requires allowing the (intentional) `dbg!` use in the sample, as one would have expected. Finally, in a single case, the `allow` is fixed to be an inner attribute, since otherwise it was not being applied. Link: https://github.com/rust-lang/rust-clippy/issues/11303 [1] Link: https://github.com/rust-lang/rust-clippy/issues/11307 [2] Tested-by: Gary Guo <gary@garyguo.net> Reviewed-by: Gary Guo <gary@garyguo.net> Link: https://lore.kernel.org/r/20240904204347.168520-13-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-16rust: sync: update `Arc` and `UniqueArc` to take allocation flagsWedson Almeida Filho
We also remove the `try_` prefix to align with how `Box` and `Vec` are providing methods now. `init` is temporarily updated with uses of GFP_KERNEL. These will be updated in a subsequent patch to take flags as well. Reviewed-by: Benno Lossin <benno.lossin@proton.me> Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com> Link: https://lore.kernel.org/r/20240328013603.206764-9-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-04-10samples: rust: print: Add sample code for Arc printingBoqun Feng
This both demonstrates the usage of different print format in Rust and serves as a selftest for the `Display` and `Debug` implementation of `Arc` and its friends. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Finn Behrens <fin@nyantec.com> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> Link: https://lore.kernel.org/r/20230207185216.1314638-3-boqun.feng@gmail.com [ Applied suggestions and reworded for fixing title typos. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2022-12-04rust: macros: take string literals in `module!`Gary Guo
Instead of taking binary string literals, take string ones instead, making it easier for users to define a module, i.e. instead of calling `module!` like: module! { ... name: b"rust_minimal", ... } now it is called as: module! { ... name: "rust_minimal", ... } Module names, aliases and license strings are restricted to ASCII only. However, the author and the description allows UTF-8. For simplicity (avoid parsing), escape sequences and raw string literals are not yet handled. Link: https://github.com/Rust-for-Linux/linux/issues/252 Link: https://lore.kernel.org/lkml/YukvvPOOu8uZl7+n@yadro.com/ Signed-off-by: Gary Guo <gary@garyguo.net> [Reworded, adapted for upstream and applied latest changes] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2022-12-01rust: samples: add `rust_print` exampleMiguel Ojeda
Add example to exercise the printing macros (`pr_*!`) introduced in the previous patches. Reviewed-by: Finn Behrens <me@kloenk.dev> Reviewed-by: Wei Liu <wei.liu@kernel.org> Tested-by: Sergio González Collado <sergio.collado@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>