// SPDX-License-Identifier: GPL-2.0
/*
 * KUnit test for the Kernel Hashtable structures.
 *
 * Copyright (C) 2022, Google LLC.
 * Author: Rae Moar <rmoar@google.com>
 */
#include <kunit/test.h>

#include <linux/hashtable.h>

struct hashtable_test_entry {
        int key;
        int data;
        struct hlist_node node;
        int visited;
};

static void hashtable_test_hash_init(struct kunit *test)
{
        /* Test the different ways of initialising a hashtable. */
        DEFINE_HASHTABLE(hash1, 2);
        DECLARE_HASHTABLE(hash2, 3);

        /* When using DECLARE_HASHTABLE, must use hash_init to
         * initialize the hashtable.
         */
        hash_init(hash2);

        KUNIT_EXPECT_TRUE(test, hash_empty(hash1));
        KUNIT_EXPECT_TRUE(test, hash_empty(hash2));
}

static void hashtable_test_hash_empty(struct kunit *test)
{
        struct hashtable_test_entry a;
        DEFINE_HASHTABLE(hash, 1);

        KUNIT_EXPECT_TRUE(test, hash_empty(hash));

        a.key = 1;
        a.data = 13;
        hash_add(hash, &a.node, a.key);

        /* Hashtable should no longer be empty. */
        KUNIT_EXPECT_FALSE(test, hash_empty(hash));
}

static void hashtable_test_hash_hashed(struct kunit *test)
{
        struct hashtable_test_entry a, b;
        DEFINE_HASHTABLE(hash, 4);

        a.key = 1;
        a.data = 13;
        hash_add(hash, &a.node, a.key);
        b.key = 1;
        b.data = 2;
        hash_add(hash, &b.node, b.key);

        KUNIT_EXPECT_TRUE(test, hash_hashed(&a.node));
        KUNIT_EXPECT_TRUE(test, hash_hashed(&b.node));
}

static void hashtable_test_hash_add(struct kunit *test)
{
        struct hashtable_test_entry a, b, *x;
        int bkt;
        DEFINE_HASHTABLE(hash, 3);

        a.key = 1;
        a.data = 13;
        a.visited = 0;
        hash_add(hash, &a.node, a.key);
        b.key = 2;
        b.data = 10;
        b.visited = 0;
        hash_add(hash, &b.node, b.key);

        hash_for_each(hash, bkt, x, node) {
                x->visited++;
                if (x->key == a.key)
                        KUNIT_EXPECT_EQ(test, x->data, 13);
                else if (x->key == b.key)
                        KUNIT_EXPECT_EQ(test, x->data, 10);
                else
                        KUNIT_FAIL(test, "Unexpected key in hashtable.");
        }

        /* Both entries should have been visited exactly once. */
        KUNIT_EXPECT_EQ(test, a.visited, 1);
        KUNIT_EXPECT_EQ(test, b.visited, 1);
}

static void hashtable_test_hash_del(struct kunit *test)
{
        struct hashtable_test_entry a, b, *x;
        DEFINE_HASHTABLE(hash, 6);

        a.key = 1;
        a.data = 13;
        hash_add(hash, &a.node, a.key);
        b.key = 2;
        b.data = 10;
        b.visited = 0;
        hash_add(hash, &b.node, b.key);

        hash_del(&b.node);
        hash_for_each_possible(hash, x, node, b.key) {
                x->visited++;
                KUNIT_EXPECT_NE(test, x->key, b.key);
        }

        /* The deleted entry should not have been visited. */
        KUNIT_EXPECT_EQ(test, b.visited, 0);

        hash_del(&a.node);

        /* The hashtable should be empty. */
        KUNIT_EXPECT_TRUE(test, hash_empty(hash));
}

static void hashtable_test_hash_for_each(struct kunit *test)
{
        struct hashtable_test_entry entries[3];
        struct hashtable_test_entry *x;
        int bkt, i, j, count;
        DEFINE_HASHTABLE(hash, 3);

        /* Add three entries to the hashtable. */
        for (i = 0; i < 3; i++) {
                entries[i].key = i;
                entries[i].data = i + 10;
                entries[i].visited = 0;
                hash_add(hash, &entries[i].node, entries[i].key);
        }

        count = 0;
        hash_for_each(hash, bkt, x, node) {
                x->visited += 1;
                KUNIT_ASSERT_GE_MSG(test, x->key, 0, "Unexpected key in hashtable.");
                KUNIT_ASSERT_LT_MSG(test, x->key, 3, "Unexpected key in hashtable.");
                count++;
        }

        /* Should have visited each entry exactly once. */
        KUNIT_EXPECT_EQ(test, count, 3);
        for (j = 0; j < 3; j++)
                KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
}

static void hashtable_test_hash_for_each_safe(struct kunit *test)
{
        struct hashtable_test_entry entries[3];
        struct hashtable_test_entry *x;
        struct hlist_node *tmp;
        int bkt, i, j, count;
        DEFINE_HASHTABLE(hash, 3);

        /* Add three entries to the hashtable. */
        for (i = 0; i < 3; i++) {
                entries[i].key = i;
                entries[i].data = i + 10;
                entries[i].visited = 0;
                hash_add(hash, &entries[i].node, entries[i].key);
        }

        count = 0;
        hash_for_each_safe(hash, bkt, tmp, x, node) {
                x->visited += 1;
                KUNIT_ASSERT_GE_MSG(test, x->key, 0, "Unexpected key in hashtable.");
                KUNIT_ASSERT_LT_MSG(test, x->key, 3, "Unexpected key in hashtable.");
                count++;

                /* Delete entry during loop. */
                hash_del(&x->node);
        }

        /* Should have visited each entry exactly once. */
        KUNIT_EXPECT_EQ(test, count, 3);
        for (j = 0; j < 3; j++)
                KUNIT_EXPECT_EQ(test, entries[j].visited, 1);
}

static void hashtable_test_hash_for_each_possible(struct kunit *test)
{
        struct hashtable_test_entry entries[4];
        struct hashtable_test_entry *x, *y;
        int buckets[2];
        int bkt, i, j, count;
        DEFINE_HASHTABLE(hash, 5);

        /* Add three entries with key = 0 to the hashtable. */
        for (i = 0; i < 3; i++) {
                entries[i].key = 0;
                entries[i].data = i;
                entries[i].visited = 0;
                hash_add(hash, &entries[i].node, entries[i].key);
        }

        /* Add an entry with key = 1. */
        entries[3].key = 1;
        entries[3].data = 3;
        entries[3].visited = 0;
        hash_add(hash, &entries[3].node, entries[3].key);

        count = 0;
        hash_for_each_possible(hash, x, node, 0) {
                x->visited += 1;
                KUNIT_ASSERT_GE_MSG(test, x->data, 0, "Unexpected data in hashtable.");
                KUNIT_ASSERT_LT_MSG(test, x->data, 4, "Unexpected data in hashtable.");
                count++;
        }

        /* Should have visited each entry with key = 0 exactly once. */
        for (j = 0; j < 3; j++)
                KUNIT_EXPECT_EQ(test, entries[j].visited, 1);

        /* Save the buckets for the different keys. */
        hash_for_each(hash, bkt, y, node) {
                KUNIT_ASSERT_GE_MSG(test, y->key, 0, "Unexpected key in hashtable.");
                KUNIT_ASSERT_LE_MSG(test, y->key, 1, "Unexpected key in hashtable.");
                buckets[y->key] = bkt;
        }

        /* If entry with key = 1 is in the same bucket as the entries with
         * key = 0, check it was visited. Otherwise ensure that only three
         * entries were visited.
         */
        if (buckets[0] == buckets[1]) {
                KUNIT_EXPECT_EQ(test, count, 4);
                KUNIT_EXPECT_EQ(test, entries[3].visited, 1);
        } else {
                KUNIT_EXPECT_EQ(test, count, 3);
                KUNIT_EXPECT_EQ(test, entries[3].visited, 0);
        }
}

static void hashtable_test_hash_for_each_possible_safe(struct kunit *test)
{
        struct hashtable_test_entry entries[4];
        struct hashtable_test_entry *x, *y;
        struct hlist_node *tmp;
        int buckets[2];
        int bkt, i, j, count;
        DEFINE_HASHTABLE(hash, 5);

        /* Add three entries with key = 0 to the hashtable. */
        for (i = 0; i < 3; i++) {
                entries[i].key = 0;
                entries[i].data = i;
                entries[i].visited = 0;
                hash_add(hash, &entries[i].node, entries[i].key);
        }

        /* Add an entry with key = 1. */
        entries[3].key = 1;
        entries[3].data = 3;
        entries[3].visited = 0;
        hash_add(hash, &entries[3].node, entries[3].key);

        count = 0;
        hash_for_each_possible_safe(hash, x, tmp, node, 0) {
                x->visited += 1;
                KUNIT_ASSERT_GE_MSG(test, x->data, 0, "Unexpected data in hashtable.");
                KUNIT_ASSERT_LT_MSG(test, x->data, 4, "Unexpected data in hashtable.");
                count++;

                /* Delete entry during loop. */
                hash_del(&x->node);
        }

        /* Should have visited each entry with key = 0 exactly once. */
        for (j = 0; j < 3; j++)
                KUNIT_EXPECT_EQ(test, entries[j].visited, 1);

        /* Save the buckets for the different keys. */
        hash_for_each(hash, bkt, y, node) {
                KUNIT_ASSERT_GE_MSG(test, y->key, 0, "Unexpected key in hashtable.");
                KUNIT_ASSERT_LE_MSG(test, y->key, 1, "Unexpected key in hashtable.");
                buckets[y->key] = bkt;
        }

        /* If entry with key = 1 is in the same bucket as the entries with
         * key = 0, check it was visited. Otherwise ensure that only three
         * entries were visited.
         */
        if (buckets[0] == buckets[1]) {
                KUNIT_EXPECT_EQ(test, count, 4);
                KUNIT_EXPECT_EQ(test, entries[3].visited, 1);
        } else {
                KUNIT_EXPECT_EQ(test, count, 3);
                KUNIT_EXPECT_EQ(test, entries[3].visited, 0);
        }
}

static struct kunit_case hashtable_test_cases[] = {
        KUNIT_CASE(hashtable_test_hash_init),
        KUNIT_CASE(hashtable_test_hash_empty),
        KUNIT_CASE(hashtable_test_hash_hashed),
        KUNIT_CASE(hashtable_test_hash_add),
        KUNIT_CASE(hashtable_test_hash_del),
        KUNIT_CASE(hashtable_test_hash_for_each),
        KUNIT_CASE(hashtable_test_hash_for_each_safe),
        KUNIT_CASE(hashtable_test_hash_for_each_possible),
        KUNIT_CASE(hashtable_test_hash_for_each_possible_safe),
        {},
};

static struct kunit_suite hashtable_test_module = {
        .name = "hashtable",
        .test_cases = hashtable_test_cases,
};

kunit_test_suites(&hashtable_test_module);

MODULE_DESCRIPTION("KUnit test for the Kernel Hashtable structures");
MODULE_LICENSE("GPL");