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2025-05-27rust: add `kunit_tests` to the preludeMiguel Ojeda
It is convenient to have certain things in the `kernel` prelude, and means kernel developers will find it even easier to start writing tests. And, anyway, nobody should need to use this identifier for anything else. Thus add it to the prelude. Reviewed-by: David Gow <davidgow@google.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/r/20250502215133.1923676-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-27rust: kunit: support checked `-> Result`s in KUnit `#[test]`sMiguel Ojeda
Currently, return values of KUnit `#[test]` functions are ignored. Thus introduce support for `-> Result` functions by checking their returned values. At the same time, require that test functions return `()` or `Result<T, E>`, which should avoid mistakes, especially with non-`#[must_use]` types. Other types can be supported in the future if needed. With this, a failing test like: #[test] fn my_test() -> Result { f()?; Ok(()) } will output: [ 3.744214] KTAP version 1 [ 3.744287] # Subtest: my_test_suite [ 3.744378] # speed: normal [ 3.744399] 1..1 [ 3.745817] # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321 [ 3.745817] Expected is_test_result_ok(my_test()) to be true, but is false [ 3.747152] # my_test.speed: normal [ 3.747199] not ok 1 my_test [ 3.747345] not ok 4 my_test_suite Reviewed-by: David Gow <davidgow@google.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/r/20250502215133.1923676-3-ojeda@kernel.org [ Used `::kernel` for paths. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-27rust: kunit: support KUnit-mapped `assert!` macros in `#[test]`sMiguel Ojeda
The KUnit `#[test]` support that landed recently is very basic and does not map the `assert*!` macros into KUnit like the doctests do, so they panic at the moment. Thus implement the custom mapping in a similar way to doctests, reusing the infrastructure there. In Rust 1.88.0, the `file()` method in `Span` may be stable [1]. However, it was changed recently (from `SourceFile`), so we need to do something different in previous versions. Thus create a helper for it and use it to get the path. With this, a failing test suite like: #[kunit_tests(my_test_suite)] mod tests { use super::*; #[test] fn my_first_test() { assert_eq!(42, 43); } #[test] fn my_second_test() { assert!(42 >= 43); } } will properly map back to KUnit, printing something like: [ 1.924325] KTAP version 1 [ 1.924421] # Subtest: my_test_suite [ 1.924506] # speed: normal [ 1.924525] 1..2 [ 1.926385] # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251 [ 1.926385] Expected 42 == 43 to be true, but is false [ 1.928026] # my_first_test.speed: normal [ 1.928075] not ok 1 my_first_test [ 1.928723] # my_second_test: ASSERTION FAILED at rust/kernel/lib.rs:256 [ 1.928723] Expected 42 >= 43 to be true, but is false [ 1.929834] # my_second_test.speed: normal [ 1.929868] not ok 2 my_second_test [ 1.930032] # my_test_suite: pass:0 fail:2 skip:0 total:2 [ 1.930153] # Totals: pass:0 fail:2 skip:0 total Link: https://github.com/rust-lang/rust/pull/140514 [1] Reviewed-by: David Gow <davidgow@google.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://lore.kernel.org/r/20250502215133.1923676-2-ojeda@kernel.org [ Required `KUNIT=y` like for doctests. Used the `cfg_attr` from the TODO comment and clarified its comment now that the stabilization is in beta and thus quite likely stable in Rust 1.88.0. Simplified the `new_body` code by introducing a new variable. Added `#[allow(clippy::incompatible_msrv)]`. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-23rust: use absolute paths in macros referencing core and kernelIgor Korotin
Macros and auto-generated code should use absolute paths, `::core::...` and `::kernel::...`, for core and kernel references. This prevents issues where user-defined modules named `core` or `kernel` could be picked up instead of the `core` or `kernel` crates. Thus clean some references up. Suggested-by: Benno Lossin <benno.lossin@proton.me> Closes: https://github.com/Rust-for-Linux/linux/issues/1150 Signed-off-by: Igor Korotin <igor.korotin.linux@gmail.com> Reviewed-by: Benno Lossin <lossin@kernel.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/20250519164615.3310844-1-igor.korotin.linux@gmail.com [ Applied `rustfmt`. Reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20rust: kunit: allow to know if we are in a testJosé Expósito
In some cases, we need to call test-only code from outside the test case, for example, to mock a function or a module. In order to check whether we are in a test or not, we need to test if `CONFIG_KUNIT` is set. Unfortunately, we cannot rely only on this condition because: - a test could be running in another thread, - some distros compile KUnit in production kernels, so checking at runtime that `current->kunit_test != NULL` is required. Forturately, KUnit provides an optimised check in `kunit_get_current_test()`, which checks CONFIG_KUNIT, a global static key, and then the current thread's running KUnit test. Add a safe wrapper function around this to know whether or not we are in a KUnit test and examples showing how to mock a function and a module. Signed-off-by: José Expósito <jose.exposito89@gmail.com> Co-developed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Co-developed-by: David Gow <davidgow@google.com> Signed-off-by: David Gow <davidgow@google.com> Link: https://lore.kernel.org/r/20250307090103.918788-4-davidgow@google.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20rust: macros: add macro to easily run KUnit testsJosé Expósito
Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to run KUnit tests using a user-space like syntax. The macro, that should be used on modules, transforms every `#[test]` in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering all of them. The only difference with user-space tests is that instead of using `#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used. Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not compiled when `CONFIG_KUNIT` is set to `n`. Reviewed-by: David Gow <davidgow@google.com> Signed-off-by: José Expósito <jose.exposito89@gmail.com> Co-developed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Co-developed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Tamir Duberstein <tamird@gmail.com> Signed-off-by: David Gow <davidgow@google.com> Link: https://lore.kernel.org/r/20250307090103.918788-3-davidgow@google.com [ Removed spurious (in rendered form) newline in docs. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20rust: kunit: add KUnit case and suite macrosJosé Expósito
Add a couple of Rust const functions and macros to allow to develop KUnit tests without relying on generated C code: - The `kunit_unsafe_test_suite!` Rust macro is similar to the `kunit_test_suite` C macro. It requires a NULL-terminated array of test cases (see below). - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro. It generates as case from the name and function. - The `kunit_case_null` Rust function generates a NULL test case, which is to be used as delimiter in `kunit_test_suite!`. While these functions and macros can be used on their own, a future patch will introduce another macro to create KUnit tests using a user-space like syntax. Signed-off-by: José Expósito <jose.exposito89@gmail.com> Co-developed-by: Matt Gilbride <mattgilbride@google.com> Signed-off-by: Matt Gilbride <mattgilbride@google.com> Co-developed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Co-developed-by: David Gow <davidgow@google.com> Signed-off-by: David Gow <davidgow@google.com> Link: https://lore.kernel.org/r/20250307090103.918788-2-davidgow@google.com [ Applied Markdown in comment. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-01rust: kunit: use C-string literals to clean warningMiguel Ojeda
Starting with upstream Rust commit a5e3a3f9b6bd ("move `manual_c_str_literals` to complexity"), to be released in Rust 1.83.0 [1], Clippy now warns on `manual_c_str_literals` by default, e.g.: error: manually constructing a nul-terminated string --> rust/kernel/kunit.rs:21:13 | 21 | b"\x013%pA\0".as_ptr() as _, | ^^^^^^^^^^^^^ help: use a `c""` literal: `c"\x013%pA"` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_c_str_literals = note: `-D clippy::manual-c-str-literals` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::manual_c_str_literals)]` Apply the suggestion to clean up the warnings. Link: https://github.com/rust-lang/rust-clippy/pull/13263 [1] Reviewed-by: Trevor Gross <tmgross@umich.edu> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20240927164414.560906-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-12-21rust: support `srctree`-relative linksMiguel Ojeda
Some of our links use relative paths in order to point to files in the source tree, e.g.: //! C header: [`include/linux/printk.h`](../../../../include/linux/printk.h) /// [`struct mutex`]: ../../../../include/linux/mutex.h These are problematic because they are hard to maintain and do not support `O=` builds. Instead, provide support for `srctree`-relative links, e.g.: //! C header: [`include/linux/printk.h`](srctree/include/linux/printk.h) /// [`struct mutex`]: srctree/include/linux/mutex.h The links are fixed after `rustdoc` generation to be based on the absolute path to the source tree. Essentially, this is the automatic version of Tomonori's fix [1], suggested by Gary [2]. Suggested-by: Gary Guo <gary@garyguo.net> Reported-by: FUJITA Tomonori <fujita.tomonori@gmail.com> Closes: https://lore.kernel.org/r/20231026.204058.2167744626131849993.fujita.tomonori@gmail.com [1] Fixes: 48fadf440075 ("docs: Move rustdoc output, cross-reference it") Link: https://lore.kernel.org/rust-for-linux/20231026154525.6d14b495@eugeo/ [2] Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20231215235428.243211-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-07-19rust: support running Rust documentation tests as KUnit onesMiguel Ojeda
Rust has documentation tests: these are typically examples of usage of any item (e.g. function, struct, module...). They are very convenient because they are just written alongside the documentation. For instance: /// Sums two numbers. /// /// ``` /// assert_eq!(mymod::f(10, 20), 30); /// ``` pub fn f(a: i32, b: i32) -> i32 { a + b } In userspace, the tests are collected and run via `rustdoc`. Using the tool as-is would be useful already, since it allows to compile-test most tests (thus enforcing they are kept in sync with the code they document) and run those that do not depend on in-kernel APIs. However, by transforming the tests into a KUnit test suite, they can also be run inside the kernel. Moreover, the tests get to be compiled as other Rust kernel objects instead of targeting userspace. On top of that, the integration with KUnit means the Rust support gets to reuse the existing testing facilities. For instance, the kernel log would look like: KTAP version 1 1..1 KTAP version 1 # Subtest: rust_doctests_kernel 1..59 # rust_doctest_kernel_build_assert_rs_0.location: rust/kernel/build_assert.rs:13 ok 1 rust_doctest_kernel_build_assert_rs_0 # rust_doctest_kernel_build_assert_rs_1.location: rust/kernel/build_assert.rs:56 ok 2 rust_doctest_kernel_build_assert_rs_1 # rust_doctest_kernel_init_rs_0.location: rust/kernel/init.rs:122 ok 3 rust_doctest_kernel_init_rs_0 ... # rust_doctest_kernel_types_rs_2.location: rust/kernel/types.rs:150 ok 59 rust_doctest_kernel_types_rs_2 # rust_doctests_kernel: pass:59 fail:0 skip:0 total:59 # Totals: pass:59 fail:0 skip:0 total:59 ok 1 rust_doctests_kernel Therefore, add support for running Rust documentation tests in KUnit. Some other notes about the current implementation and support follow. The transformation is performed by a couple scripts written as Rust hostprogs. Tests using the `?` operator are also supported as usual, e.g.: /// ``` /// # use kernel::{spawn_work_item, workqueue}; /// spawn_work_item!(workqueue::system(), || pr_info!("x"))?; /// # Ok::<(), Error>(()) /// ``` The tests are also compiled with Clippy under `CLIPPY=1`, just like normal code, thus also benefitting from extra linting. The names of the tests are currently automatically generated. This allows to reduce the burden for documentation writers, while keeping them fairly stable for bisection. This is an improvement over the `rustdoc`-generated names, which include the line number; but ideally we would like to get `rustdoc` to provide the Rust item path and a number (for multiple examples in a single documented Rust item). In order for developers to easily see from which original line a failed doctests came from, a KTAP diagnostic line is printed to the log, containing the location (file and line) of the original test (i.e. instead of the location in the generated Rust file): # rust_doctest_kernel_types_rs_2.location: rust/kernel/types.rs:150 This line follows the syntax for declaring test metadata in the proposed KTAP v2 spec [1], which may be used for the proposed KUnit test attributes API [2]. Thus hopefully this will make migration easier later on (suggested by David [3]). The original line in that test attribute is figured out by providing an anchor (suggested by Boqun [4]). The original file is found by walking the filesystem, checking directory prefixes to reduce the amount of combinations to check, and it is only done once per file. Ambiguities are detected and reported. A notable difference from KUnit C tests is that the Rust tests appear to assert using the usual `assert!` and `assert_eq!` macros from the Rust standard library (`core`). We provide a custom version that forwards the call to KUnit instead. Importantly, these macros do not require passing context, unlike the KUnit C ones (i.e. `struct kunit *`). This makes them easier to use, and readers of the documentation do not need to care about which testing framework is used. In addition, it may allow us to test third-party code more easily in the future. However, a current limitation is that KUnit does not support assertions in other tasks. Thus we presently simply print an error to the kernel log if an assertion actually failed. This should be revisited to properly fail the test, perhaps saving the context somewhere else, or letting KUnit handle it. Link: https://lore.kernel.org/lkml/20230420205734.1288498-1-rmoar@google.com/ [1] Link: https://lore.kernel.org/linux-kselftest/20230707210947.1208717-1-rmoar@google.com/ [2] Link: https://lore.kernel.org/rust-for-linux/CABVgOSkOLO-8v6kdAGpmYnZUb+LKOX0CtYCo-Bge7r_2YTuXDQ@mail.gmail.com/ [3] Link: https://lore.kernel.org/rust-for-linux/ZIps86MbJF%2FiGIzd@boqun-archlinux/ [4] Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: David Gow <davidgow@google.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>