lib/test: convert test_sort.c to use KUnit

This follows up commit ebd09577 ("lib/test: convert
lib/test_list_sort.c to use KUnit").

Converting this test to KUnit makes the test a bit shorter, standardizes
how it reports pass/fail, and adds an easier way to run the test [1].

Like ebd09577, this leaves the file and Kconfig option name the same,
but slightly changes their dependencies (needs CONFIG_KUNIT).

[1] Can be run via
$ ./tools/testing/kunit/kunit.py run --kunitconfig /dev/stdin <<EOF
CONFIG_KUNIT=y
CONFIG_TEST_SORT=y
EOF

[11:30:27] Starting KUnit Kernel ...
[11:30:30] ============================================================
[11:30:30] ======== [PASSED] lib_sort ========
[11:30:30] [PASSED] test_sort
[11:30:30] ============================================================
[11:30:30] Testing complete. 1 tests run. 0 failed. 0 crashed. 0 skipped.
[11:30:30] Elapsed time: 37.032s total, 0.001s configuring, 34.090s building, 0.000s running

Note: this is the time it took after a `make mrproper`.

With an incremental rebuild, this looks more like:
[11:38:58] Elapsed time: 6.444s total, 0.001s configuring, 3.416s building, 0.000s running

Since the test has no dependencies, it can also be run (with some other
tests) with just:
$ ./tools/testing/kunit/kunit.py run

Link: https://lkml.kernel.org/r/20210715232441.1380885-1-dlatypov@google.comSigned-off-by: Daniel Latypov <dlatypov@google.com>
Cc: Pravin Shedge <pravin.shedge4linux@gmail.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -2078,8 +2078,9 @@ config TEST_MIN_HEAP
 	  If unsure, say N.
 
 config TEST_SORT
-	tristate "Array-based sort test"
-	depends on DEBUG_KERNEL || m
+	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
 	help
 	  This option enables the self-test function of 'sort()' at boot,
 	  or at module load time.

lib/test_sort.c

 // SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+
 #include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -7,18 +10,17 @@
 
 #define TEST_LEN 1000
 
-static int __init cmpint(const void *a, const void *b)
+static int cmpint(const void *a, const void *b)
 {
 	return *(int *)a - *(int *)b;
 }
 
-static int __init test_sort_init(void)
+static void test_sort(struct kunit *test)
 {
-	int *a, i, r = 1, err = -ENOMEM;
+	int *a, i, r = 1;
 
-	a = kmalloc_array(TEST_LEN, sizeof(*a), GFP_KERNEL);
-	if (!a)
-		return err;
+	a = kunit_kmalloc_array(test, TEST_LEN, sizeof(*a), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a);
 
 	for (i = 0; i < TEST_LEN; i++) {
 		r = (r * 725861) % 6599;
@@ -27,24 +29,20 @@ static int __init test_sort_init(void)
 
 	sort(a, TEST_LEN, sizeof(*a), cmpint, NULL);
 
-	err = -EINVAL;
 	for (i = 0; i < TEST_LEN-1; i++)
-		if (a[i] > a[i+1]) {
-			pr_err("test has failed\n");
-			goto exit;
-		}
-	err = 0;
-	pr_info("test passed\n");
-exit:
-	kfree(a);
-	return err;
+		KUNIT_ASSERT_LE(test, a[i], a[i + 1]);
 }
 
-static void __exit test_sort_exit(void)
-{
-}
+static struct kunit_case sort_test_cases[] = {
+	KUNIT_CASE(test_sort),
+	{}
+};
+
+static struct kunit_suite sort_test_suite = {
+	.name = "lib_sort",
+	.test_cases = sort_test_cases,
+};
 
-module_init(test_sort_init);
-module_exit(test_sort_exit);
+kunit_test_suites(&sort_test_suite);
 
 MODULE_LICENSE("GPL");