Very excited to see this progress. On Fri, Feb 14, 2025 at 2:41 AM David Gow <davidgow@xxxxxxxxxx> wrote: > > From: José Expósito <jose.exposito89@xxxxxxxxx> > > 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@xxxxxxxxx> > Co-developed-by: Matt Gilbride <mattgilbride@xxxxxxxxxx> > Signed-off-by: Matt Gilbride <mattgilbride@xxxxxxxxxx> > Co-developed-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > Co-developed-by: David Gow <davidgow@xxxxxxxxxx> > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> > --- > > Changes since v5: > https://lore.kernel.org/all/20241213081035.2069066-2-davidgow@xxxxxxxxxx/ > - Rebased against 6.14-rc1 > - Several documentation touch-ups, including noting that the example > test function need not be unsafe. (Thanks, Miguel) > - Remove the need for static_mut_refs, by using core::addr_of_mut!() > combined with a cast. (Thanks, Miguel) > - While this should also avoid the need for const_mut_refs, it seems > to have been enabled for other users anyway. > - Use ::kernel::ffi::c_char for C strings, rather than i8 directly. > (Thanks, Miguel) > > Changes since v4: > https://lore.kernel.org/linux-kselftest/20241101064505.3820737-2-davidgow@xxxxxxxxxx/ > - Rebased against 6.13-rc1 > - Allowed an unused_unsafe warning after the behaviour of addr_of_mut!() > changed in Rust 1.82. (Thanks Boqun, Miguel) > - Fix a couple of minor rustfmt issues which were triggering checkpatch > warnings. > > Changes since v3: > https://lore.kernel.org/linux-kselftest/20241030045719.3085147-4-davidgow@xxxxxxxxxx/ > - The kunit_unsafe_test_suite!() macro now panic!s if the suite name is > too long, triggering a compile error. (Thanks, Alice!) > > Changes since v2: > https://lore.kernel.org/linux-kselftest/20241029092422.2884505-2-davidgow@xxxxxxxxxx/ > - The kunit_unsafe_test_suite!() macro will truncate the name of the > suite if it is too long. (Thanks Alice!) > - We no longer needlessly use UnsafeCell<> in > kunit_unsafe_test_suite!(). (Thanks Alice!) > > Changes since v1: > https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@xxxxxxxxxx/ > - Rebase on top of rust-next > - As a result, KUnit attributes are new set. These are hardcoded to the > defaults of "normal" speed and no module name. > - Split the kunit_case!() macro into two const functions, kunit_case() > and kunit_case_null() (for the NULL terminator). > > --- > rust/kernel/kunit.rs | 121 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 121 insertions(+) > > diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs > index 824da0e9738a..d34a92075174 100644 > --- a/rust/kernel/kunit.rs > +++ b/rust/kernel/kunit.rs > @@ -161,3 +161,124 @@ macro_rules! kunit_assert_eq { > $crate::kunit_assert!($name, $file, $diff, $left == $right); > }}; > } > + > +/// Represents an individual test case. > +/// > +/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of valid test cases. > +/// Use `kunit_case_null` to generate such a delimiter. Can both of these be linkified? [`kunit_unsafe_test_suite!`] and [`kunit_case_null`]. There are more instances below. > +#[doc(hidden)] > +pub const fn kunit_case( > + name: &'static kernel::str::CStr, > + run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit), > +) -> kernel::bindings::kunit_case { > + kernel::bindings::kunit_case { > + run_case: Some(run_case), > + name: name.as_char_ptr(), > + attr: kernel::bindings::kunit_attributes { > + speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL, > + }, > + generate_params: None, > + status: kernel::bindings::kunit_status_KUNIT_SUCCESS, > + module_name: core::ptr::null_mut(), > + log: core::ptr::null_mut(), These members, after `name`, can be spelled `..kunit_case_null()` to avoid some repetition. > + } > +} > + > +/// Represents the NULL test case delimiter. > +/// > +/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases. This > +/// function returns such a delimiter. > +#[doc(hidden)] > +pub const fn kunit_case_null() -> kernel::bindings::kunit_case { > + kernel::bindings::kunit_case { > + run_case: None, > + name: core::ptr::null_mut(), > + generate_params: None, > + attr: kernel::bindings::kunit_attributes { > + speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL, > + }, > + status: kernel::bindings::kunit_status_KUNIT_SUCCESS, > + module_name: core::ptr::null_mut(), > + log: core::ptr::null_mut(), > + } > +} > + > +/// Registers a KUnit test suite. > +/// > +/// # Safety > +/// > +/// `test_cases` must be a NULL terminated array of valid test cases. > +/// > +/// # Examples > +/// > +/// ```ignore > +/// extern "C" fn test_fn(_test: *mut kernel::bindings::kunit) { > +/// let actual = 1 + 1; > +/// let expected = 2; > +/// assert_eq!(actual, expected); > +/// } > +/// > +/// static mut KUNIT_TEST_CASES: [kernel::bindings::kunit_case; 2] = [ > +/// kernel::kunit::kunit_case(kernel::c_str!("name"), test_fn), > +/// kernel::kunit::kunit_case_null(), > +/// ]; > +/// kernel::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES); > +/// ``` > +#[doc(hidden)] > +#[macro_export] > +macro_rules! kunit_unsafe_test_suite { > + ($name:ident, $test_cases:ident) => { > + const _: () = { > + const KUNIT_TEST_SUITE_NAME: [::kernel::ffi::c_char; 256] = { > + let name_u8 = ::core::stringify!($name).as_bytes(); This can be a little simpler: let name = $crate::c_str!(::core::stringify!($name)).as_bytes_with_nul(); > + let mut ret = [0; 256]; > + > + if name_u8.len() > 255 { > + panic!(concat!( > + "The test suite name `", > + ::core::stringify!($name), > + "` exceeds the maximum length of 255 bytes." > + )); > + } > + > + let mut i = 0; > + while i < name_u8.len() { > + ret[i] = name_u8[i] as ::kernel::ffi::c_char; > + i += 1; > + } I'd suggest `ret[..name.len()].copy_from_slice(name)` but `copy_from_slice` isn't `const`. This can stay the same with the now-unnecessary cast removed, or it can be the body of `copy_from_slice`: // SAFETY: `name` is valid for `name.len()` elements by definition, and `ret` was // checked to be at least as large as `name`. The buffers are statically know to not // overlap. unsafe { ::core::ptr::copy_nonoverlapping(name.as_ptr(), ret.as_mut_ptr(), name.len()); } > + > + ret > + }; > + > + #[allow(unused_unsafe)] > + static mut KUNIT_TEST_SUITE: ::kernel::bindings::kunit_suite = > + ::kernel::bindings::kunit_suite { > + name: KUNIT_TEST_SUITE_NAME, > + // SAFETY: User is expected to pass a correct `test_cases`, given the safety > + // precondition; hence this macro named `unsafe`. > + test_cases: unsafe { > + ::core::ptr::addr_of_mut!($test_cases) > + .cast::<::kernel::bindings::kunit_case>() > + }, This safety comment seems to be referring to the safety of `addr_of_mut!` but this was just a compiler limitation until Rust 1.82, right? Same thing below on `KUNIT_TEST_SUITE_ENTRY`. Can we also narrow the `#[allow]`? This seems to work: #[allow(unused_unsafe)] // SAFETY: ... test_cases: unsafe { ::core::ptr::addr_of_mut!($test_cases) .cast::<::kernel::bindings::kunit_case>() }, > + suite_init: None, > + suite_exit: None, > + init: None, > + exit: None, > + attr: ::kernel::bindings::kunit_attributes { > + speed: ::kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL, > + }, > + status_comment: [0; 256usize], I don't think you need the usize hint here, there's always a usize in the length position. > + debugfs: ::core::ptr::null_mut(), > + log: ::core::ptr::null_mut(), > + suite_init_err: 0, > + is_init: false, > + }; > + > + #[used] > + #[link_section = ".kunit_test_suites"] This attribute causes the same problem I describe in https://lore.kernel.org/all/20250210-macros-section-v2-1-3bb9ff44b969@xxxxxxxxx/. That's because the KUnit tests are generated both on target and on host (even though they won't run on host). I don't think you need to deal with that here, just pointing it out. I think we'll need a cfg to indicate we're building for host to avoid emitting these attributes that only make sense in the kernel. > + static mut KUNIT_TEST_SUITE_ENTRY: *const ::kernel::bindings::kunit_suite = > + // SAFETY: `KUNIT_TEST_SUITE` is static. > + unsafe { ::core::ptr::addr_of_mut!(KUNIT_TEST_SUITE) }; This is missing the `#[allow(unused_unsafe)]` (it appears in the next patch). This means this commit will not compile on bisection. > + }; > + }; > +} > -- > 2.48.1.601.g30ceb7b040-goog > > Global note: it seems more customary to use crate:: and $crate:: instead of kernel:: and ::kernel in functions and macros, respectively. Cheers. Tamir
