kunit: Add test attributes API structure

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 "# [<test_name if
not suite>.]<attribute_name>: <attribute_value>".

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 <[e-mail]>
Signed-off-by: Rae Moar <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

include/kunit/attributes.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KUnit API to save and access test attributes
+ *
+ * Copyright (C) 2023, Google LLC.
+ * Author: Rae Moar <[e-mail]>
+ */
+
+#ifndef _KUNIT_ATTRIBUTES_H
+#define _KUNIT_ATTRIBUTES_H
+
+/*
+ * Print all test attributes for a test case or suite.
+ * Output format for test cases: "# <test_name>.<attribute>: <value>"
+ * Output format for test suites: "# <attribute>: <value>"
+ */
+void kunit_print_attr(void *test_or_suite, bool is_test, unsigned int test_level);
+
+#endif /* _KUNIT_ATTRIBUTES_H */

include/kunit/test.h

···
 	KUNIT_SKIPPED,
 };
 
+/* Holds attributes for each test case and suite */
+struct kunit_attributes {};
+
 /**
  * struct kunit_case - represents an individual test case.
  *
  * @run_case: the function representing the actual test case.
  * @name:     the name of the test case.
  * @generate_params: the generator function for parameterized tests.
+ * @attr:     the attributes associated with the test
  *
  * A test case is a function with the signature,
  * ``void (*)(struct kunit *)``
···
 	void (*run_case)(struct kunit *test);
 	const char *name;
 	const void* (*generate_params)(const void *prev, char *desc);
+	struct kunit_attributes attr;
 
 	/* private: internal use only. */
 	enum kunit_status status;
···
 #define KUNIT_CASE(test_name) { .run_case = test_name, .name = #test_name }
 
 /**
+ * KUNIT_CASE_ATTR - A helper for creating a &struct kunit_case
+ * with attributes
+ *
+ * @test_name: a reference to a test case function.
+ * @attributes: a reference to a struct kunit_attributes object containing
+ * test attributes
+ */
+#define KUNIT_CASE_ATTR(test_name, attributes)			\
+		{ .run_case = test_name, .name = #test_name,	\
+		  .attr = attributes }
+
+/**
  * KUNIT_CASE_PARAM - A helper for creation a parameterized &struct kunit_case
  *
  * @test_name: a reference to a test case function.
···
 		  .generate_params = gen_params }
 
 /**
+ * KUNIT_CASE_PARAM_ATTR - A helper for creating a parameterized &struct
+ * kunit_case with attributes
+ *
+ * @test_name: a reference to a test case function.
+ * @gen_params: a reference to a parameter generator function.
+ * @attributes: a reference to a struct kunit_attributes object containing
+ * test attributes
+ */
+#define KUNIT_CASE_PARAM_ATTR(test_name, gen_params, attributes)	\
+		{ .run_case = test_name, .name = #test_name,	\
+		  .generate_params = gen_params,				\
+		  .attr = attributes }
+
+/**
  * struct kunit_suite - describes a related collection of &struct kunit_case
  *
  * @name:	the name of the test. Purely informational.
···
  * @init:	called before every test case.
  * @exit:	called after every test case.
  * @test_cases:	a null terminated array of test cases.
+ * @attr:	the attributes associated with the test suite
  *
  * A kunit_suite is a collection of related &struct kunit_case s, such that
  * @init is called before every test case and @exit is called after every
···
 	int (*init)(struct kunit *test);
 	void (*exit)(struct kunit *test);
 	struct kunit_case *test_cases;
+	struct kunit_attributes attr;
 
 	/* private: internal use only */
 	char status_comment[KUNIT_STATUS_COMMENT_SIZE];

lib/kunit/Makefile

···
 					string-stream.o \
 					assert.o \
 					try-catch.o \
-					executor.o
+					executor.o \
+					attributes.o
 
 ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
 kunit-objs +=				debugfs.o

lib/kunit/attributes.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit API to save and access test attributes
+ *
+ * Copyright (C) 2023, Google LLC.
+ * Author: Rae Moar <[e-mail]>
+ */
+
+#include <kunit/test.h>
+#include <kunit/attributes.h>
+
+/* Options for printing attributes:
+ * PRINT_ALWAYS - attribute is printed for every test case and suite if set
+ * PRINT_SUITE - attribute is printed for every suite if set but not for test cases
+ * PRINT_NEVER - attribute is never printed
+ */
+enum print_ops {
+	PRINT_ALWAYS,
+	PRINT_SUITE,
+	PRINT_NEVER,
+};
+
+/**
+ * struct kunit_attr - represents a test attribute and holds flexible
+ * helper functions to interact with attribute.
+ *
+ * @name: name of test attribute, eg. speed
+ * @get_attr: function to return attribute value given a test
+ * @to_string: function to return string representation of given
+ * attribute value
+ * @filter: function to indicate whether a given attribute value passes a
+ * filter
+ */
+struct kunit_attr {
+	const char *name;
+	void *(*get_attr)(void *test_or_suite, bool is_test);
+	const char *(*to_string)(void *attr, bool *to_free);
+	int (*filter)(void *attr, const char *input, int *err);
+	void *attr_default;
+	enum print_ops print;
+};
+
+/* List of all Test Attributes */
+
+static struct kunit_attr kunit_attr_list[] = {};
+
+/* Helper Functions to Access Attributes */
+
+void kunit_print_attr(void *test_or_suite, bool is_test, unsigned int test_level)
+{
+	int i;
+	bool to_free;
+	void *attr;
+	const char *attr_name, *attr_str;
+	struct kunit_suite *suite = is_test ? NULL : test_or_suite;
+	struct kunit_case *test = is_test ? test_or_suite : NULL;
+
+	for (i = 0; i < ARRAY_SIZE(kunit_attr_list); i++) {
+		if (kunit_attr_list[i].print == PRINT_NEVER ||
+				(test && kunit_attr_list[i].print == PRINT_SUITE))
+			continue;
+		attr = kunit_attr_list[i].get_attr(test_or_suite, is_test);
+		if (attr) {
+			attr_name = kunit_attr_list[i].name;
+			attr_str = kunit_attr_list[i].to_string(attr, &to_free);
+			if (test) {
+				kunit_log(KERN_INFO, test, "%*s# %s.%s: %s",
+					KUNIT_INDENT_LEN * test_level, "", test->name,
+					attr_name, attr_str);
+			} else {
+				kunit_log(KERN_INFO, suite, "%*s# %s: %s",
+					KUNIT_INDENT_LEN * test_level, "", attr_name, attr_str);
+			}
+
+			/* Free to_string of attribute if needed */
+			if (to_free)
+				kfree(attr_str);
+		}
+	}
+}

lib/kunit/executor.c

···
 
 #include <linux/reboot.h>
 #include <kunit/test.h>
+#include <kunit/attributes.h>
 #include <linux/glob.h>
 #include <linux/moduleparam.h>
 
···
 MODULE_PARM_DESC(action,
 		 "Changes KUnit executor behavior, valid values are:\n"
 		 "<none>: run the tests like normal\n"
-		 "'list' to list test names instead of running them.\n");
+		 "'list' to list test names instead of running them.\n"
+		 "'list_attr' to list test names and attributes instead of running them.\n");
 
 /* glob_match() needs NULL terminated strings, so we need a copy of filter_glob_param. */
 struct kunit_test_filter {
···
 	__kunit_test_suites_init(suite_set->start, num_suites);
 }
 
-static void kunit_exec_list_tests(struct suite_set *suite_set)
+static void kunit_exec_list_tests(struct suite_set *suite_set, bool include_attr)
 {
 	struct kunit_suite * const *suites;
 	struct kunit_case *test_case;
···
 	/* Hack: print a ktap header so kunit.py can find the start of KUnit output. */
 	pr_info("KTAP version 1\n");
 
-	for (suites = suite_set->start; suites < suite_set->end; suites++)
+	for (suites = suite_set->start; suites < suite_set->end; suites++) {
+		/* Print suite name and suite attributes */
+		pr_info("%s\n", (*suites)->name);
+		if (include_attr)
+			kunit_print_attr((void *)(*suites), false, 0);
+
+		/* Print test case name and attributes in suite */
 		kunit_suite_for_each_test_case((*suites), test_case) {
 			pr_info("%s.%s\n", (*suites)->name, test_case->name);
+			if (include_attr)
+				kunit_print_attr((void *)test_case, true, 0);
 		}
+	}
 }
 
 int kunit_run_all_tests(void)
···
 	if (!action_param)
 		kunit_exec_run_tests(&suite_set);
 	else if (strcmp(action_param, "list") == 0)
-		kunit_exec_list_tests(&suite_set);
+		kunit_exec_list_tests(&suite_set, false);
+	else if (strcmp(action_param, "list_attr") == 0)
+		kunit_exec_list_tests(&suite_set, true);
 	else
 		pr_err("kunit executor: unknown action '%s'\n", action_param);
 

lib/kunit/test.c

···
 #include <kunit/resource.h>
 #include <kunit/test.h>
 #include <kunit/test-bug.h>
+#include <kunit/attributes.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
···
 }
 EXPORT_SYMBOL_GPL(kunit_suite_num_test_cases);
 
+/* Currently supported test levels */
+enum {
+	KUNIT_LEVEL_SUITE = 0,
+	KUNIT_LEVEL_CASE,
+	KUNIT_LEVEL_CASE_PARAM,
+};
+
 static void kunit_print_suite_start(struct kunit_suite *suite)
 {
 	/*
···
 	pr_info(KUNIT_SUBTEST_INDENT "KTAP version 1\n");
 	pr_info(KUNIT_SUBTEST_INDENT "# Subtest: %s\n",
 		  suite->name);
+	kunit_print_attr((void *)suite, false, KUNIT_LEVEL_CASE);
 	pr_info(KUNIT_SUBTEST_INDENT "1..%zd\n",
 		  kunit_suite_num_test_cases(suite));
 }
-
-/* Currently supported test levels */
-enum {
-	KUNIT_LEVEL_SUITE = 0,
-	KUNIT_LEVEL_CASE,
-	KUNIT_LEVEL_CASE_PARAM,
-};
 
 static void kunit_print_ok_not_ok(struct kunit *test,
 				  unsigned int test_level,
···
 			}
 		}
 
+		kunit_print_attr((void *)test_case, true, KUNIT_LEVEL_CASE);
 
 		kunit_print_test_stats(&test, param_stats);