kernel/linux.git/lib/kunit/Makefile, branch v7.2-rc1

kunit: Add backtrace suppression self-tests

2026-05-14T16:50:00+00:00

Add unit tests to verify that warning backtrace suppression works. Tests cover both API forms: - Scoped: kunit_warning_suppress() with in-block count verification and post-block inactivity check. - Direct functions: kunit_start/end_suppress_warning() with sequential independent suppression blocks and per-block counts. Furthermore, tests verify incremental warning counting, that kunit_has_active_suppress_warning() transitions correctly around suppression boundaries, and that suppression active in the test kthread does not leak to a separate kthread. If backtrace suppression does _not_ work, the unit tests will likely trigger unsuppressed backtraces, which should actually help to get the affected architectures / platforms fixed. Link: https://lore.kernel.org/r/20260514-kunit_add_support-v11-2-b36a530a6d8f@redhat.com Tested-by: Linux Kernel Functional Testing Acked-by: Dan Carpenter Reviewed-by: Kees Cook Signed-off-by: Guenter Roeck Signed-off-by: Alessandro Carminati Reviewed-by: David Gow Signed-off-by: Albert Esteve Signed-off-by: Shuah Khan

bug/kunit: Core support for suppressing warning backtraces

2026-05-14T16:50:00+00:00

Some unit tests intentionally trigger warning backtraces by passing bad parameters to kernel API functions. Such unit tests typically check the return value from such calls, not the existence of the warning backtrace. Such intentionally generated warning backtraces are neither desirable nor useful for a number of reasons: - They can result in overlooked real problems. - A warning that suddenly starts to show up in unit tests needs to be investigated and has to be marked to be ignored, for example by adjusting filter scripts. Such filters are ad hoc because there is no real standard format for warnings. On top of that, such filter scripts would require constant maintenance. Solve the problem by providing a means to suppress warning backtraces originating from the current kthread while executing test code. Since each KUnit test runs in its own kthread, this effectively scopes suppression to the test that enabled it. Limit changes to generic code to the absolute minimum. Implementation details: Suppression is integrated into the existing KUnit hooks infrastructure in test-bug.h, reusing the kunit_running static branch for zero overhead when no tests are running. Suppression is checked at three points in the warning path: - In warn_slowpath_fmt(), the check runs before any output, fully suppressing both message and backtrace. This covers architectures without __WARN_FLAGS. - In __warn_printk(), the check suppresses the warning message text. This covers architectures that define __WARN_FLAGS but not their own __WARN_printf (arm64, loongarch, parisc, powerpc, riscv, sh), where the message is printed before the trap enters __report_bug(). - In __report_bug(), the check runs before __warn() is called, suppressing the backtrace and stack dump. To avoid double-counting on architectures where both __warn_printk() and __report_bug() run for the same warning, kunit_is_suppressed_warning() takes a bool parameter: true to increment the suppression counter (used in warn_slowpath_fmt and __report_bug), false to check only (used in __warn_printk). The suppression state is dynamically allocated via kunit_kzalloc() and tied to the KUnit test lifecycle via kunit_add_action(), ensuring automatic cleanup at test exit. Writer-side access to the global suppression list is serialized with a spinlock; readers use RCU. Two API forms are provided: - kunit_warning_suppress(test) { ... }: scoped, uses __cleanup for automatic teardown on scope exit, kunit_add_action() as safety net for abnormal exits (e.g. kthread_exit from failed assertions). Suppression handle is only accessible inside the block. - kunit_start/end_suppress_warning(test): direct functions returning an explicit handle, for retaining the handle within the test, or for cross-function usage. Link: https://lore.kernel.org/r/20260514-kunit_add_support-v11-1-b36a530a6d8f@redhat.com Signed-off-by: Guenter Roeck Signed-off-by: Alessandro Carminati Reviewed-by: Kees Cook Reviewed-by: David Gow Signed-off-by: Albert Esteve Signed-off-by: Shuah Khan

kunit: Always descend into kunit directory during build

2025-08-15T17:39:46+00:00

For kbuild to properly clean up these build artifacts in the subdirectory, even after CONFIG_KUNIT changed do disabled, the directory needs to be processed always. Pushing the special logic for hook.o into the kunit Makefile also makes the logic easier to understand. Link: https://lore.kernel.org/r/20250813-kunit-always-descend-v1-1-7bbd387ff13b@linutronix.de Signed-off-by: Thomas Weißschuh Reviewed-by: David Gow Signed-off-by: Shuah Khan

platform: Add test managed platform_device/driver APIs

2024-07-29T22:33:12+00:00

Introduce KUnit resource wrappers around platform_driver_register(), platform_device_alloc(), and platform_device_add() so that test authors can register platform drivers/devices from their tests and have the drivers/devices automatically be unregistered when the test is done. This makes test setup code simpler when a platform driver or platform device is needed. Add a few test cases at the same time to make sure the APIs work as intended. Cc: Brendan Higgins Reviewed-by: David Gow Cc: Rae Moar Reviewed-by: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Signed-off-by: Stephen Boyd Link: https://lore.kernel.org/r/20240718210513.3801024-6-sboyd@kernel.org

kunit: test: Add vm_mmap() allocation resource manager

2024-06-15T01:31:33+00:00

For tests that need to allocate using vm_mmap() (e.g. usercopy and execve), provide the interface to have the allocation tracked by KUnit itself. This requires bringing up a placeholder userspace mm. This combines my earlier attempt at this with Mark Rutland's version[1]. Normally alloc_mm() and arch_pick_mmap_layout() aren't exported for modules, so export these only for KUnit testing. Link: https://lore.kernel.org/lkml/20230321122514.1743889-2-mark.rutland@arm.com/ [1] Co-developed-by: Mark Rutland Signed-off-by: Mark Rutland Reviewed-by: David Gow Signed-off-by: Kees Cook Signed-off-by: Shuah Khan

kunit: Cover 'assert.c' with tests

2024-05-30T18:53:47+00:00

There are multiple assertion formatting functions in the `assert.c` file, which are not covered with tests yet. Implement the KUnit test for these functions. The test consists of 11 test cases for the following functions: 1) 'is_literal' 2) 'is_str_literal' 3) 'kunit_assert_prologue', test case for multiple assert types 4) 'kunit_assert_print_msg' 5) 'kunit_unary_assert_format' 6) 'kunit_ptr_not_err_assert_format' 7) 'kunit_binary_assert_format' 8) 'kunit_binary_ptr_assert_format' 9) 'kunit_binary_str_assert_format' 10) 'kunit_assert_hexdump' 11) 'kunit_mem_assert_format' The test aims at maximizing the branch coverage for the assertion formatting functions. As you can see, it covers some of the static helper functions as well, so mark the static functions in `assert.c` as 'VISIBLE_IF_KUNIT' and conditionally export them with EXPORT_SYMBOL_IF_KUNIT. Add the corresponding definitions to `assert.h`. Build the assert test when CONFIG_KUNIT_TEST is enabled, similar to how it is done for the string stream test. Signed-off-by: Ivan Orlov Reviewed-by: Rae Moar Acked-by: David Gow Signed-off-by: Shuah Khan

kunit: Add APIs for managing devices

2023-12-18T20:28:08+00:00

Tests for drivers often require a struct device to pass to other functions. While it's possible to create these with root_device_register(), or to use something like a platform device, this is both a misuse of those APIs, and can be difficult to clean up after, for example, a failed assertion. Add some KUnit-specific functions for registering and unregistering a struct device: - kunit_device_register() - kunit_device_register_with_driver() - kunit_device_unregister() These helpers allocate a on a 'kunit' bus which will either probe the driver passed in (kunit_device_register_with_driver), or will create a stub driver (kunit_device_register) which is cleaned up on test shutdown. Devices are automatically unregistered on test shutdown, but can be manually unregistered earlier with kunit_device_unregister() in order to, for example, test device release code. Reviewed-by: Matti Vaittinen Reviewed-by: Maxime Ripard Signed-off-by: David Gow Reviewed-by: Greg Kroah-Hartman Signed-off-by: Shuah Khan

kunit: Add test attributes API structure

2023-07-26T19:28:57+00:00

Add the basic structure of the test attribute API to KUnit, which can be used to save and access test associated data. Add attributes.c and attributes.h to hold associated structs and functions for the API. Create a struct that holds a variety of associated helper functions for each test attribute. These helper functions will be used to get the attribute value, convert the value to a string, and filter based on the value. This struct is flexible by design to allow for attributes of numerous types and contexts. Add a method to print test attributes in the format of "# [.]: ". Example for a suite: "# speed: slow" Example for a test case: "# test_case.speed: very_slow" Use this method to report attributes in the KTAP output (KTAP spec: https://docs.kernel.org/dev-tools/ktap.html) and _list_tests output when kernel's new kunit.action=list_attr option is used. Note this is derivative of the kunit.action=list option. In test.h, add fields and associated helper functions to test cases and suites to hold user-inputted test attributes. Reviewed-by: David Gow Signed-off-by: Rae Moar Signed-off-by: Shuah Khan

kunit: Fix 'hooks.o' build by recursing into kunit

2023-02-27T22:49:03+00:00

KUnit's 'hooks.o' file need to be built-in whenever KUnit is enabled (even if CONFIG_KUNIT=m). We'd previously attemtped to do this by adding 'kunit/hooks.o' to obj-y in lib/Makefile, but this caused hooks.c to be rebuilt even when it was unchanged. Instead, always recurse into lib/kunit using obj-y when KUnit is enabled, and add the hooks there. Fixes: 7170b7ed6acb ("kunit: Add "hooks" to call into KUnit when it's built as a module"). Reported-by: Linus Torvalds Link: https://lore.kernel.org/linux-kselftest/CAHk-=wiEf7irTKwPJ0jTMOF3CS-13UXmF6Fns3wuWpOZ_wGyZQ@mail.gmail.com/ Signed-off-by: David Gow Reviewed-by: Brendan Higgins Signed-off-by: Linus Torvalds

kunit: Expose 'static stub' API to redirect functions

2023-02-08T21:28:17+00:00

Add a simple way of redirecting calls to functions by including a special prologue in the "real" function which checks to see if the replacement function should be called (and, if so, calls it). To redirect calls to a function, make the first (non-declaration) line of the function: KUNIT_STATIC_STUB_REDIRECT(function_name, [function arguments]); (This will compile away to nothing if KUnit is not enabled, otherwise it will check if a redirection is active, call the replacement function, and return. This check is protected by a static branch, so has very little overhead when there are no KUnit tests running.) Calls to the real function can be redirected to a replacement using: kunit_activate_static_stub(test, real_fn, replacement_fn); The redirection will only affect calls made from within the kthread of the current test, and will be automatically disabled when the test completes. It can also be manually disabled with kunit_deactivate_static_stub(). The 'example' KUnit test suite has a more complete example. Co-developed-by: Daniel Latypov Signed-off-by: Daniel Latypov Signed-off-by: David Gow Reviewed-by: Brendan Higgins Signed-off-by: Shuah Khan