// SPDX-License-Identifier: GPL-2.0-only

#include <kunit/test.h>

#include <linux/ratelimit.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/cpumask.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 / 2);
        test_ratelimited(test, false);

        schedule_timeout_idle(TESTRL_INTERVAL * 3 / 4);
        test_ratelimited(test, true);

        schedule_timeout_idle(2 * TESTRL_INTERVAL);
        test_ratelimited(test, true);
        test_ratelimited(test, true);

        schedule_timeout_idle(TESTRL_INTERVAL / 2 );
        test_ratelimited(test, true);
        schedule_timeout_idle(TESTRL_INTERVAL * 3 / 4);
        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 ratelimit_state stressrl = RATELIMIT_STATE_INIT_FLAGS("stressrl", HZ / 10, 3,
                                                                    RATELIMIT_MSG_ON_RELEASE);

static int doneflag;
static const int stress_duration = 2 * HZ;

struct stress_kthread {
        unsigned long nattempts;
        unsigned long nunlimited;
        unsigned long nlimited;
        unsigned long nmissed;
        struct task_struct *tp;
};

static int test_ratelimit_stress_child(void *arg)
{
        struct stress_kthread *sktp = arg;

        set_user_nice(current, MAX_NICE);
        WARN_ON_ONCE(!sktp->tp);

        while (!READ_ONCE(doneflag)) {
                sktp->nattempts++;
                if (___ratelimit(&stressrl, __func__))
                        sktp->nunlimited++;
                else
                        sktp->nlimited++;
                cond_resched();
        }

        sktp->nmissed = ratelimit_state_reset_miss(&stressrl);
        return 0;
}

static void test_ratelimit_stress(struct kunit *test)
{
        int i;
        const int n_stress_kthread = cpumask_weight(cpu_online_mask);
        struct stress_kthread skt = { 0 };
        struct stress_kthread *sktp = kzalloc_objs(*sktp, n_stress_kthread);

        KUNIT_EXPECT_NOT_NULL_MSG(test, sktp, "Memory allocation failure");
        for (i = 0; i < n_stress_kthread; i++) {
                sktp[i].tp = kthread_run(test_ratelimit_stress_child, &sktp[i], "%s/%i",
                                         "test_ratelimit_stress_child", i);
                KUNIT_EXPECT_NOT_NULL_MSG(test, sktp, "kthread creation failure");
                pr_alert("Spawned test_ratelimit_stress_child %d\n", i);
        }
        schedule_timeout_idle(stress_duration);
        WRITE_ONCE(doneflag, 1);
        for (i = 0; i < n_stress_kthread; i++) {
                kthread_stop(sktp[i].tp);
                skt.nattempts += sktp[i].nattempts;
                skt.nunlimited += sktp[i].nunlimited;
                skt.nlimited += sktp[i].nlimited;
                skt.nmissed += sktp[i].nmissed;
        }
        KUNIT_ASSERT_EQ_MSG(test, skt.nunlimited + skt.nlimited, skt.nattempts,
                            "Outcomes not equal to attempts");
        KUNIT_ASSERT_EQ_MSG(test, skt.nlimited, skt.nmissed, "Misses not equal to limits");
}

static struct kunit_case ratelimit_test_cases[] = {
        KUNIT_CASE_SLOW(test_ratelimit_smoke),
        KUNIT_CASE_SLOW(test_ratelimit_stress),
        {}
};

static struct kunit_suite ratelimit_test_suite = {
        .name = "lib_ratelimit",
        .test_cases = ratelimit_test_cases,
};

kunit_test_suites(&ratelimit_test_suite);

MODULE_DESCRIPTION("___ratelimit() KUnit test suite");
MODULE_LICENSE("GPL");