patches/old/lib-add-trivial-kunit-test-for-ratelimit.patch

From: "Paul E. McKenney" <paulmck@kernel.org>
Subject: lib: add trivial kunit test for ratelimit
Date: Wed, 9 Jul 2025 11:03:33 -0700

Patch series "ratelimit: Add tests for lib/ratelimit.c", v6.

Add a simple "smoke" test along with a simple stress test:

1.	Add trivial kunit test for ratelimit.
2.	Make the ratelimit test more reliable, courtesy of Petr Mladek.
3.	Add stress test for ratelimit.


This patch (of 3):

Add a simple single-threaded smoke test for lib/ratelimit.c

To run on x86:

	make ARCH=x86_64 mrproper
	./tools/testing/kunit/kunit.py run --arch x86_64 --kconfig_add CONFIG_RATELIMIT_KUNIT_TEST=y --kconfig_add CONFIG_SMP=y lib_ratelimit

This will fail on old ___ratelimit(), and subsequent patches provide
the fixes that are required.

[paulmck@kernel.org: apply timeout and kunit feedback from Petr Mladek]
Link: https://lkml.kernel.org/r/d1007957-97ff-4f6f-92ac-606f68c65dfa@paulmck-laptop
Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/
Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@web.de/
Link: https://lkml.kernel.org/r/20250709180335.1716384-1-paulmck@kernel.org
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Petr Mladek <pmladek@suse.com>	[timeout and kunit feedback]
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jon Pan-Doh <pandoh@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Karolina Stolarek <karolina.stolarek@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/Kconfig.debug          |   11 ++++
 lib/tests/Makefile         |    1 
 lib/tests/test_ratelimit.c |   79 +++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+)

--- a/lib/Kconfig.debug~lib-add-trivial-kunit-test-for-ratelimit
+++ a/lib/Kconfig.debug
@@ -3225,6 +3225,17 @@ config TEST_OBJPOOL
 
 	  If unsure, say N.
 
+config RATELIMIT_KUNIT_TEST
+	tristate "KUnit Test for correctness and stress of ratelimit" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the "test_ratelimit" module that should be used
+	  for correctness verification and concurrent testings of rate
+	  limiting.
+
+	  If unsure, say N.
+
 config INT_POW_KUNIT_TEST
 	tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
 	depends on KUNIT
--- a/lib/tests/Makefile~lib-add-trivial-kunit-test-for-ratelimit
+++ a/lib/tests/Makefile
@@ -46,5 +46,6 @@ obj-$(CONFIG_STRING_KUNIT_TEST) += strin
 obj-$(CONFIG_STRING_HELPERS_KUNIT_TEST) += string_helpers_kunit.o
 obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
 obj-$(CONFIG_UTIL_MACROS_KUNIT) += util_macros_kunit.o
+obj-$(CONFIG_RATELIMIT_KUNIT_TEST) += test_ratelimit.o
 
 obj-$(CONFIG_TEST_RUNTIME_MODULE)		+= module/
diff --git a/lib/tests/test_ratelimit.c a/lib/tests/test_ratelimit.c
new file mode 100644
--- /dev/null
+++ a/lib/tests/test_ratelimit.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+
+#include <linux/ratelimit.h>
+#include <linux/module.h>
+
+/* a simple boot-time regression test */
+
+#define TESTRL_INTERVAL (5 * HZ)
+static DEFINE_RATELIMIT_STATE(testrl, TESTRL_INTERVAL, 3);
+
+#define test_ratelimited(test, expected) \
+	KUNIT_ASSERT_EQ(test, ___ratelimit(&testrl, "test_ratelimit_smoke"), (expected))
+
+static void test_ratelimit_smoke(struct kunit *test)
+{
+	// Check settings.
+	KUNIT_ASSERT_GE(test, TESTRL_INTERVAL, 100);
+
+	// Test normal operation.
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+
+	schedule_timeout_idle(TESTRL_INTERVAL - 40);
+	test_ratelimited(test, false);
+
+	schedule_timeout_idle(50);
+	test_ratelimited(test, true);
+
+	schedule_timeout_idle(2 * TESTRL_INTERVAL);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+
+	schedule_timeout_idle(TESTRL_INTERVAL - 40);
+	test_ratelimited(test, true);
+	schedule_timeout_idle(50);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+
+	// Test disabling.
+	testrl.burst = 0;
+	test_ratelimited(test, false);
+	testrl.burst = 2;
+	testrl.interval = 0;
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+
+	// Testing re-enabling.
+	testrl.interval = TESTRL_INTERVAL;
+	test_ratelimited(test, true);
+	test_ratelimited(test, true);
+	test_ratelimited(test, false);
+	test_ratelimited(test, false);
+}
+
+static struct kunit_case sort_test_cases[] = {
+	KUNIT_CASE_SLOW(test_ratelimit_smoke),
+	{}
+};
+
+static struct kunit_suite ratelimit_test_suite = {
+	.name = "lib_ratelimit",
+	.test_cases = sort_test_cases,
+};
+
+kunit_test_suites(&ratelimit_test_suite);
+
+MODULE_DESCRIPTION("___ratelimit() KUnit test suite");
+MODULE_LICENSE("GPL");
_