Merge tag 'linux_kselftest-kunit-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull kunit updates from Shuah Khan:

 - New parameterized test features

   KUnit parameterized tests supported two primary methods for getting
   parameters:

    - Defining custom logic within a generate_params() function.

    - Using the KUNIT_ARRAY_PARAM() and KUNIT_ARRAY_PARAM_DESC() macros
      with a pre-defined static array and passing the created
      *_gen_params() to KUNIT_CASE_PARAM().

   These methods present limitations when dealing with dynamically
   generated parameter arrays, or in scenarios where populating
   parameters sequentially via generate_params() is inefficient or
   overly complex.

   These limitations are fixed with a parameterized test method

 - Fix issues in kunit build artifacts cleanup

 - Fix parsing skipped test problem in kselftest framework

 - Enable PCI on UML without triggering WARN()

 - a few other fixes and adds support for new configs such as MIPS

* tag 'linux_kselftest-kunit-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: Extend kconfig help text for KUNIT_UML_PCI
  rust: kunit: allow `cfg` on `test`s
  kunit: qemu_configs: Add MIPS configurations
  kunit: Enable PCI on UML without triggering WARN()
  Documentation: kunit: Document new parameterized test features
  kunit: Add example parameterized test with direct dynamic parameter array setup
  kunit: Add example parameterized test with shared resource management using the Resource API
  kunit: Enable direct registration of parameter arrays to a KUnit test
  kunit: Pass parameterized test context to generate_params()
  kunit: Introduce param_init/exit for parameterized test context management
  kunit: Add parent kunit for parameterized test context
  kunit: tool: Accept --raw_output=full as an alias of 'all'
  kunit: tool: Parse skipped tests from kselftest.h
  kunit: Always descend into kunit directory during build

Author: torvalds

Documentation/dev-tools/kunit/usage.rst

@@ -542,11 +542,31 @@ There is more boilerplate code involved, but it can:
 Parameterized Testing
 ~~~~~~~~~~~~~~~~~~~~~
 
-The table-driven testing pattern is common enough that KUnit has special
-support for it.
+To run a test case against multiple inputs, KUnit provides a parameterized
+testing framework. This feature formalizes and extends the concept of
+table-driven tests discussed previously.
 
-By reusing the same ``cases`` array from above, we can write the test as a
-"parameterized test" with the following.
+A KUnit test is determined to be parameterized if a parameter generator function
+is provided when registering the test case. A test user can either write their
+own generator function or use one that is provided by KUnit. The generator
+function is stored in  ``kunit_case->generate_params`` and can be set using the
+macros described in the section below.
+
+To establish the terminology, a "parameterized test" is a test which is run
+multiple times (once per "parameter" or "parameter run"). Each parameter run has
+both its own independent ``struct kunit`` (the "parameter run context") and
+access to a shared parent ``struct kunit`` (the "parameterized test context").
+
+Passing Parameters to a Test
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+There are three ways to provide the parameters to a test:
+
+Array Parameter Macros:
+
+   KUnit provides special support for the common table-driven testing pattern.
+   By applying either ``KUNIT_ARRAY_PARAM`` or ``KUNIT_ARRAY_PARAM_DESC`` to the
+   ``cases`` array from the previous section, we can create a parameterized test
+   as shown below:
 
 .. code-block:: c
 
@@ -555,7 +575,7 @@ By reusing the same ``cases`` array from above, we can write the test as a
 		const char *str;
 		const char *sha1;
 	};
-	const struct sha1_test_case cases[] = {
+	static const struct sha1_test_case cases[] = {
 		{
 			.str = "hello world",
 			.sha1 = "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed",
@@ -590,6 +610,318 @@ By reusing the same ``cases`` array from above, we can write the test as a
 		{}
 	};
 
+Custom Parameter Generator Function:
+
+   The generator function is responsible for generating parameters one-by-one
+   and has the following signature:
+   ``const void* (*)(struct kunit *test, const void *prev, char *desc)``.
+   You can pass the generator function to the ``KUNIT_CASE_PARAM``
+   or ``KUNIT_CASE_PARAM_WITH_INIT`` macros.
+
+   The function receives the previously generated parameter as the ``prev`` argument
+   (which is ``NULL`` on the first call) and can also access the parameterized
+   test context passed as the ``test`` argument. KUnit calls this function
+   repeatedly until it returns ``NULL``, which signifies that a parameterized
+   test ended.
+
+   Below is an example of how it works:
+
+.. code-block:: c
+
+	#define MAX_TEST_BUFFER_SIZE 8
+
+	// Example generator function. It produces a sequence of buffer sizes that
+	// are powers of two, starting at 1 (e.g., 1, 2, 4, 8).
+	static const void *buffer_size_gen_params(struct kunit *test, const void *prev, char *desc)
+	{
+		long prev_buffer_size = (long)prev;
+		long next_buffer_size = 1; // Start with an initial size of 1.
+
+		// Stop generating parameters if the limit is reached or exceeded.
+		if (prev_buffer_size >= MAX_TEST_BUFFER_SIZE)
+			return NULL;
+
+		// For subsequent calls, calculate the next size by doubling the previous one.
+		if (prev)
+			next_buffer_size = prev_buffer_size << 1;
+
+		return (void *)next_buffer_size;
+	}
+
+	// Simple test to validate that kunit_kzalloc provides zeroed memory.
+	static void buffer_zero_test(struct kunit *test)
+	{
+		long buffer_size = (long)test->param_value;
+		// Use kunit_kzalloc to allocate a zero-initialized buffer. This makes the
+		// memory "parameter run managed," meaning it's automatically cleaned up at
+		// the end of each parameter run.
+		int *buf = kunit_kzalloc(test, buffer_size * sizeof(int), GFP_KERNEL);
+
+		// Ensure the allocation was successful.
+		KUNIT_ASSERT_NOT_NULL(test, buf);
+
+		// Loop through the buffer and confirm every element is zero.
+		for (int i = 0; i < buffer_size; i++)
+			KUNIT_EXPECT_EQ(test, buf[i], 0);
+	}
+
+	static struct kunit_case buffer_test_cases[] = {
+		KUNIT_CASE_PARAM(buffer_zero_test, buffer_size_gen_params),
+		{}
+	};
+
+Runtime Parameter Array Registration in the Init Function:
+
+   For scenarios where you might need to initialize a parameterized test, you
+   can directly register a parameter array to the parameterized test context.
+
+   To do this, you must pass the parameterized test context, the array itself,
+   the array size, and a ``get_description()`` function to the
+   ``kunit_register_params_array()`` macro. This macro populates
+   ``struct kunit_params`` within the parameterized test context, effectively
+   storing a parameter array object. The ``get_description()`` function will
+   be used for populating parameter descriptions and has the following signature:
+   ``void (*)(struct kunit *test, const void *param, char *desc)``. Note that it
+   also has access to the parameterized test context.
+
+      .. important::
+         When using this way to register a parameter array, you will need to
+         manually pass ``kunit_array_gen_params()`` as the generator function to
+         ``KUNIT_CASE_PARAM_WITH_INIT``. ``kunit_array_gen_params()`` is a KUnit
+         helper that will use the registered array to generate the parameters.
+
+	 If needed, instead of passing the KUnit helper, you can also pass your
+	 own custom generator function that utilizes the parameter array. To
+	 access the parameter array from within the parameter generator
+	 function use ``test->params_array.params``.
+
+   The ``kunit_register_params_array()`` macro should be called within a
+   ``param_init()`` function that initializes the parameterized test and has
+   the following signature ``int (*)(struct kunit *test)``. For a detailed
+   explanation of this mechanism please refer to the "Adding Shared Resources"
+   section that is after this one. This method supports registering both
+   dynamically built and static parameter arrays.
+
+   The code snippet below shows the ``example_param_init_dynamic_arr`` test that
+   utilizes ``make_fibonacci_params()`` to create a dynamic array, which is then
+   registered using ``kunit_register_params_array()``. To see the full code
+   please refer to lib/kunit/kunit-example-test.c.
+
+.. code-block:: c
+
+	/*
+	* Example of a parameterized test param_init() function that registers a dynamic
+	* array of parameters.
+	*/
+	static int example_param_init_dynamic_arr(struct kunit *test)
+	{
+		size_t seq_size;
+		int *fibonacci_params;
+
+		kunit_info(test, "initializing parameterized test\n");
+
+		seq_size = 6;
+		fibonacci_params = make_fibonacci_params(test, seq_size);
+		if (!fibonacci_params)
+			return -ENOMEM;
+		/*
+		* Passes the dynamic parameter array information to the parameterized test
+		* context struct kunit. The array and its metadata will be stored in
+		* test->parent->params_array. The array itself will be located in
+		* params_data.params.
+		*/
+		kunit_register_params_array(test, fibonacci_params, seq_size,
+					example_param_dynamic_arr_get_desc);
+		return 0;
+	}
+
+	static struct kunit_case example_test_cases[] = {
+		/*
+		 * Note how we pass kunit_array_gen_params() to use the array we
+		 * registered in example_param_init_dynamic_arr() to generate
+		 * parameters.
+		 */
+		KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_dynamic_arr,
+					   kunit_array_gen_params,
+					   example_param_init_dynamic_arr,
+					   example_param_exit_dynamic_arr),
+		{}
+	};
+
+Adding Shared Resources
+^^^^^^^^^^^^^^^^^^^^^^^
+All parameter runs in this framework hold a reference to the parameterized test
+context, which can be accessed using the parent ``struct kunit`` pointer. The
+parameterized test context is not used to execute any test logic itself; instead,
+it serves as a container for shared resources.
+
+It's possible to add resources to share between parameter runs within a
+parameterized test by using ``KUNIT_CASE_PARAM_WITH_INIT``, to which you pass
+custom ``param_init()`` and ``param_exit()`` functions. These functions run once
+before and once after the parameterized test, respectively.
+
+The ``param_init()`` function, with the signature ``int (*)(struct kunit *test)``,
+can be used for adding resources to the ``resources`` or ``priv`` fields of
+the parameterized test context, registering the parameter array, and any other
+initialization logic.
+
+The ``param_exit()`` function, with the signature ``void (*)(struct kunit *test)``,
+can be used to release any resources that were not parameterized test managed (i.e.
+not automatically cleaned up after the parameterized test ends) and for any other
+exit logic.
+
+Both ``param_init()`` and ``param_exit()`` are passed the parameterized test
+context behind the scenes. However, the test case function receives the parameter
+run context. Therefore, to manage and access shared resources from within a test
+case function, you must use ``test->parent``.
+
+For instance, finding a shared resource allocated by the Resource API requires
+passing ``test->parent`` to ``kunit_find_resource()``. This principle extends to
+all other APIs that might be used in the test case function, including
+``kunit_kzalloc()``, ``kunit_kmalloc_array()``, and others (see
+Documentation/dev-tools/kunit/api/test.rst and the
+Documentation/dev-tools/kunit/api/resource.rst).
+
+.. note::
+   The ``suite->init()`` function, which executes before each parameter run,
+   receives the parameter run context. Therefore, any resources set up in
+   ``suite->init()`` are cleaned up after each parameter run.
+
+The code below shows how you can add the shared resources. Note that this code
+utilizes the Resource API, which you can read more about here:
+Documentation/dev-tools/kunit/api/resource.rst. To see the full version of this
+code please refer to lib/kunit/kunit-example-test.c.
+
+.. code-block:: c
+
+	static int example_resource_init(struct kunit_resource *res, void *context)
+	{
+		... /* Code that allocates memory and stores context in res->data. */
+	}
+
+	/* This function deallocates memory for the kunit_resource->data field. */
+	static void example_resource_free(struct kunit_resource *res)
+	{
+		kfree(res->data);
+	}
+
+	/* This match function locates a test resource based on defined criteria. */
+	static bool example_resource_alloc_match(struct kunit *test, struct kunit_resource *res,
+						 void *match_data)
+	{
+		return res->data && res->free == example_resource_free;
+	}
+
+	/* Function to initialize the parameterized test. */
+	static int example_param_init(struct kunit *test)
+	{
+		int ctx = 3; /* Data to be stored. */
+		void *data = kunit_alloc_resource(test, example_resource_init,
+						  example_resource_free,
+						  GFP_KERNEL, &ctx);
+		if (!data)
+			return -ENOMEM;
+		kunit_register_params_array(test, example_params_array,
+					    ARRAY_SIZE(example_params_array));
+		return 0;
+	}
+
+	/* Example test that uses shared resources in test->resources. */
+	static void example_params_test_with_init(struct kunit *test)
+	{
+		int threshold;
+		const struct example_param *param = test->param_value;
+		/*  Here we pass test->parent to access the parameterized test context. */
+		struct kunit_resource *res = kunit_find_resource(test->parent,
+								 example_resource_alloc_match,
+								 NULL);
+
+		threshold = *((int *)res->data);
+		KUNIT_ASSERT_LE(test, param->value, threshold);
+		kunit_put_resource(res);
+	}
+
+	static struct kunit_case example_test_cases[] = {
+		KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init, kunit_array_gen_params,
+					   example_param_init, NULL),
+		{}
+	};
+
+As an alternative to using the KUnit Resource API for sharing resources, you can
+place them in ``test->parent->priv``. This serves as a more lightweight method
+for resource storage, best for scenarios where complex resource management is
+not required.
+
+As stated previously ``param_init()`` and ``param_exit()`` get the parameterized
+test context. So, you can directly use ``test->priv`` within ``param_init/exit``
+to manage shared resources. However, from within the test case function, you must
+navigate up to the parent ``struct kunit`` i.e. the parameterized test context.
+Therefore, you need to use ``test->parent->priv`` to access those same
+resources.
+
+The resources placed in ``test->parent->priv`` will need to be allocated in
+memory to persist across the parameter runs. If memory is allocated using the
+KUnit memory allocation APIs (described more in the "Allocating Memory" section
+below), you won't need to worry about deallocation. The APIs will make the memory
+parameterized test 'managed', ensuring that it will automatically get cleaned up
+after the parameterized test concludes.
+
+The code below demonstrates example usage of the ``priv`` field for shared
+resources:
+
+.. code-block:: c
+
+	static const struct example_param {
+		int value;
+	} example_params_array[] = {
+		{ .value = 3, },
+		{ .value = 2, },
+		{ .value = 1, },
+		{ .value = 0, },
+	};
+
+	/* Initialize the parameterized test context. */
+	static int example_param_init_priv(struct kunit *test)
+	{
+		int ctx = 3; /* Data to be stored. */
+		int arr_size = ARRAY_SIZE(example_params_array);
+
+		/*
+		 * Allocate memory using kunit_kzalloc(). Since the `param_init`
+		 * function receives the parameterized test context, this memory
+		 * allocation will be scoped to the lifetime of the parameterized test.
+		 */
+		test->priv = kunit_kzalloc(test, sizeof(int), GFP_KERNEL);
+
+		/* Assign the context value to test->priv.*/
+		*((int *)test->priv) = ctx;
+
+		/* Register the parameter array. */
+		kunit_register_params_array(test, example_params_array, arr_size, NULL);
+		return 0;
+	}
+
+	static void example_params_test_with_init_priv(struct kunit *test)
+	{
+		int threshold;
+		const struct example_param *param = test->param_value;
+
+		/* By design, test->parent will not be NULL. */
+		KUNIT_ASSERT_NOT_NULL(test, test->parent);
+
+		/* Here we use test->parent->priv to access the shared resource. */
+		threshold = *(int *)test->parent->priv;
+
+		KUNIT_ASSERT_LE(test, param->value, threshold);
+	}
+
+	static struct kunit_case example_tests[] = {
+		KUNIT_CASE_PARAM_WITH_INIT(example_params_test_with_init_priv,
+					   kunit_array_gen_params,
+					   example_param_init_priv, NULL),
+		{}
+	};
+
 Allocating Memory
 -----------------