lib: Add trivial kunit test for ratelimit

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:  Apply timeout and kunit feedback from Petr Mladek. ]

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/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ebe33181b6e6e0fb4243b400e9187881707efe23..d69d27f8083401f9dbe40b55c1a80ac8aa29f681 100644 (file)
--- a/lib/Kconfig.debug
+++ b/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

diff --git a/lib/tests/Makefile b/lib/tests/Makefile
index 56d6450144828ee7bfe27878d3fca33dc863fd3d..3edc30a51584044b005ccdbe514db0abd37b51e5 100644 (file)
--- a/lib/tests/Makefile
+++ b/lib/tests/Makefile
@@ -46,5 +46,6 @@ obj-$(CONFIG_STRING_KUNIT_TEST) += string_kunit.o
 obj-$(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 b/lib/tests/test_ratelimit.c
new file mode 100644 (file)
index 0000000..0374107
--- /dev/null
+++ b/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");