[RESEND,v2] lib: overflow-test: add KUnit test of check_*_overflow functions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d74ac0fd6b2d..fb8a3955e969 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2000,9 +2000,6 @@  config TEST_UUID
 config TEST_XARRAY
 	tristate "Test the XArray code at runtime"
 
-config TEST_OVERFLOW
-	tristate "Test check_*_overflow() functions at runtime"
-
 config TEST_RHASHTABLE
 	tristate "Perform selftest on resizable hash table"
 	help
@@ -2155,6 +2152,23 @@  config SYSCTL_KUNIT_TEST
 
 	  If unsure, say N.
 
+config OVERFLOW_KUNIT_TEST
+	tristate "KUnit test for overflow" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the overflow KUnit tests.
+
+	  KUnit tests run during boot and output the results to the debug log
+	  in TAP format (http://testanything.org/). Only useful for kernel devs
+	  running KUnit test harness and are not for inclusion into a production
+	  build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
 config LIST_KUNIT_TEST
 	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
 	depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index b1c42c10073b..3b725c9f92d4 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -75,7 +75,6 @@  obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
 obj-$(CONFIG_TEST_MIN_HEAP) += test_min_heap.o
 obj-$(CONFIG_TEST_LKM) += test_module.o
 obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
-obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
 obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
@@ -318,3 +317,4 @@  obj-$(CONFIG_OBJAGG) += objagg.o
 # KUnit tests
 obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
 obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
+obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow-test.o
diff --git a/lib/test_overflow.c b/lib/overflow-test.c
similarity index 96%
rename from lib/test_overflow.c
rename to lib/overflow-test.c
index 7a4b6f6c5473..d40ef06b1ade 100644
--- a/lib/test_overflow.c
+++ b/lib/overflow-test.c
@@ -4,14 +4,11 @@ 
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <kunit/test.h>
 #include <linux/device.h>
 #include <linux/init.h>
-#include <linux/kernel.h>
 #include <linux/mm.h>
-#include <linux/module.h>
 #include <linux/overflow.h>
-#include <linux/slab.h>
-#include <linux/types.h>
 #include <linux/vmalloc.h>
 
 #define DEFINE_TEST_ARRAY(t)			\
@@ -270,7 +267,7 @@  DEFINE_TEST_FUNC(u64, "%llu");
 DEFINE_TEST_FUNC(s64, "%lld");
 #endif
 
-static int __init test_overflow_calculation(void)
+static void __init overflow_calculation_test(struct kunit *test)
 {
 	int err = 0;
 
@@ -285,10 +282,10 @@  static int __init test_overflow_calculation(void)
 	err |= test_s64_overflow();
 #endif
 
-	return err;
+	KUNIT_EXPECT_FALSE(test, err);
 }
 
-static int __init test_overflow_shift(void)
+static void __init overflow_shift_test(struct kunit *test)
 {
 	int err = 0;
 
@@ -479,7 +476,7 @@  static int __init test_overflow_shift(void)
 	err |= TEST_ONE_SHIFT(0, 31, s32, 0, false);
 	err |= TEST_ONE_SHIFT(0, 63, s64, 0, false);
 
-	return err;
+	KUNIT_EXPECT_FALSE(test, err);
 }
 
 /*
@@ -555,7 +552,7 @@  DEFINE_TEST_ALLOC(kvzalloc_node, kvfree,     0, 1, 1);
 DEFINE_TEST_ALLOC(devm_kmalloc,  devm_kfree, 1, 1, 0);
 DEFINE_TEST_ALLOC(devm_kzalloc,  devm_kfree, 1, 1, 0);
 
-static int __init test_overflow_allocation(void)
+static void __init overflow_allocation_test(struct kunit *test)
 {
 	const char device_name[] = "overflow-test";
 	struct device *dev;
@@ -563,10 +560,8 @@  static int __init test_overflow_allocation(void)
 
 	/* Create dummy device for devm_kmalloc()-family tests. */
 	dev = root_device_register(device_name);
-	if (IS_ERR(dev)) {
-		pr_warn("Cannot register test device\n");
-		return 1;
-	}
+	if (IS_ERR(dev))
+		kunit_warn(test, "Cannot register test device\n");
 
 	err |= test_kmalloc(NULL);
 	err |= test_kmalloc_node(NULL);
@@ -585,30 +580,21 @@  static int __init test_overflow_allocation(void)
 
 	device_unregister(dev);
 
-	return err;
+	KUNIT_EXPECT_FALSE(test, err);
 }
 
-static int __init test_module_init(void)
-{
-	int err = 0;
-
-	err |= test_overflow_calculation();
-	err |= test_overflow_shift();
-	err |= test_overflow_allocation();
-
-	if (err) {
-		pr_warn("FAIL!\n");
-		err = -EINVAL;
-	} else {
-		pr_info("all tests passed\n");
-	}
+static struct kunit_case __refdata overflow_test_cases[] = {
+	KUNIT_CASE(overflow_calculation_test),
+	KUNIT_CASE(overflow_shift_test),
+	KUNIT_CASE(overflow_allocation_test),
+	{}
+};
 
-	return err;
-}
+static struct kunit_suite overflow_test_suite = {
+	.name = "overflow",
+	.test_cases = overflow_test_cases,
+};
 
-static void __exit test_module_exit(void)
-{ }
+kunit_test_suites(&overflow_test_suite);
 
-module_init(test_module_init);
-module_exit(test_module_exit);
 MODULE_LICENSE("Dual MIT/GPL");