kunit: unify module and builtin suite definitions

Currently, KUnit runs built-in tests and tests loaded from modules
differently. For built-in tests, the kunit_test_suite{,s}() macro adds a
list of suites in the .kunit_test_suites linker section. However, for
kernel modules, a module_init() function is used to run the test suites.

This causes problems if tests are included in a module which already
defines module_init/exit_module functions, as they'll conflict with the
kunit-provided ones.

This change removes the kunit-defined module inits, and instead parses
the kunit tests from their own section in the module. After module init,
we call __kunit_test_suites_init() on the contents of that section,
which prepares and runs the suite.

This essentially unifies the module- and non-module kunit init formats.

Tested-by: Maíra Canal <[e-mail]>
Reviewed-by: Brendan Higgins <[e-mail]>
Signed-off-by: Jeremy Kerr <[e-mail]>
Signed-off-by: Daniel Latypov <[e-mail]>
Signed-off-by: David Gow <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

include/kunit/test.h

···
 }
 #endif /* IS_BUILTIN(CONFIG_KUNIT) */
 
-#ifdef MODULE
-/**
- * kunit_test_suites_for_module() - used to register one or more
- *			 &struct kunit_suite with KUnit.
- *
- * @__suites: a statically allocated list of &struct kunit_suite.
- *
- * Registers @__suites with the test framework. See &struct kunit_suite for
- * more information.
- *
- * If a test suite is built-in, module_init() gets translated into
- * an initcall which we don't want as the idea is that for builtins
- * the executor will manage execution.  So ensure we do not define
- * module_{init|exit} functions for the builtin case when registering
- * suites via kunit_test_suites() below.
- */
-#define kunit_test_suites_for_module(__suites)				\
-	static int __init kunit_test_suites_init(void)			\
-	{								\
-		return __kunit_test_suites_init(__suites);		\
-	}								\
-	module_init(kunit_test_suites_init);				\
-									\
-	static void __exit kunit_test_suites_exit(void)			\
-	{								\
-		return __kunit_test_suites_exit(__suites);		\
-	}								\
-	module_exit(kunit_test_suites_exit)				\
-	MODULE_INFO(test, "Y");
-#else
-#define kunit_test_suites_for_module(__suites)
-#endif /* MODULE */
-
 #define __kunit_test_suites(unique_array, unique_suites, ...)		       \
+	MODULE_INFO(test, "Y");						       \
 	static struct kunit_suite *unique_array[] = { __VA_ARGS__, NULL };     \
-	kunit_test_suites_for_module(unique_array);			       \
 	static struct kunit_suite **unique_suites			       \
 	__used __section(".kunit_test_suites") = unique_array
 
···
  *
  * @__suites: a statically allocated list of &struct kunit_suite.
  *
- * Registers @suites with the test framework. See &struct kunit_suite for
- * more information.
+ * Registers @suites with the test framework.
+ * This is done by placing the array of struct kunit_suite * in the
+ * .kunit_test_suites ELF section.
  *
- * When builtin,  KUnit tests are all run via executor; this is done
- * by placing the array of struct kunit_suite * in the .kunit_test_suites
- * ELF section.
- *
- * An alternative is to build the tests as a module.  Because modules do not
- * support multiple initcall()s, we need to initialize an array of suites for a
- * module.
+ * When builtin, KUnit tests are all run via the executor at boot, and when
+ * built as a module, they run on module load.
  *
  */
 #define kunit_test_suites(__suites...)						\

include/linux/module.h

···
 	int num_static_call_sites;
 	struct static_call_site *static_call_sites;
 #endif
+#if IS_ENABLED(CONFIG_KUNIT)
+	int num_kunit_suites;
+	struct kunit_suite ***kunit_suites;
+#endif
+
 
 #ifdef CONFIG_LIVEPATCH
 	bool klp; /* Is this a livepatch module? */

kernel/module/main.c

···
 					      sizeof(*mod->static_call_sites),
 					      &mod->num_static_call_sites);
 #endif
+#ifdef CONFIG_KUNIT
+	mod->kunit_suites = section_objs(info, ".kunit_test_suites",
+					      sizeof(*mod->kunit_suites),
+					      &mod->num_kunit_suites);
+#endif
+
 	mod->extable = section_objs(info, "__ex_table",
 				    sizeof(*mod->extable), &mod->num_exentries);
 

lib/kunit/test.c

···
 #include <kunit/test.h>
 #include <kunit/test-bug.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/panic.h>
 #include <linux/sched/debug.h>
···
 }
 EXPORT_SYMBOL_GPL(__kunit_test_suites_exit);
 
+#ifdef CONFIG_MODULES
+static void kunit_module_init(struct module *mod)
+{
+	unsigned int i;
+
+	for (i = 0; i < mod->num_kunit_suites; i++)
+		__kunit_test_suites_init(mod->kunit_suites[i]);
+}
+
+static void kunit_module_exit(struct module *mod)
+{
+	unsigned int i;
+
+	for (i = 0; i < mod->num_kunit_suites; i++)
+		__kunit_test_suites_exit(mod->kunit_suites[i]);
+}
+
+static int kunit_module_notify(struct notifier_block *nb, unsigned long val,
+			       void *data)
+{
+	struct module *mod = data;
+
+	switch (val) {
+	case MODULE_STATE_LIVE:
+		kunit_module_init(mod);
+		break;
+	case MODULE_STATE_GOING:
+		kunit_module_exit(mod);
+		break;
+	case MODULE_STATE_COMING:
+	case MODULE_STATE_UNFORMED:
+		break;
+	}
+
+	return 0;
+}
+
+static struct notifier_block kunit_mod_nb = {
+	.notifier_call = kunit_module_notify,
+	.priority = 0,
+};
+#endif
+
 struct kunit_kmalloc_array_params {
 	size_t n;
 	size_t size;
···
 static int __init kunit_init(void)
 {
 	kunit_debugfs_init();
-
+#ifdef CONFIG_MODULES
+	return register_module_notifier(&kunit_mod_nb);
+#else
 	return 0;
+#endif
 }
 late_initcall(kunit_init);
 
 static void __exit kunit_exit(void)
 {
+#ifdef CONFIG_MODULES
+	unregister_module_notifier(&kunit_mod_nb);
+#endif
 	kunit_debugfs_cleanup();
 }
 module_exit(kunit_exit);