2 * Resizable, Scalable, Concurrent Hash Table
4 * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch>
5 * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
7 * Based on the following paper:
8 * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf
10 * Code partially derived from nft_hash
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
17 /**************************************************************************
19 **************************************************************************/
21 #include <linux/init.h>
22 #include <linux/jhash.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/rcupdate.h>
26 #include <linux/rhashtable.h>
27 #include <linux/slab.h>
30 #define TEST_HT_SIZE 8
31 #define TEST_ENTRIES 2048
32 #define TEST_PTR ((void *) 0xdeadbeef)
33 #define TEST_NEXPANDS 4
38 struct rhash_head node;
41 static int __init test_rht_lookup(struct rhashtable *ht)
45 for (i = 0; i < TEST_ENTRIES * 2; i++) {
47 bool expected = !(i % 2);
50 obj = rhashtable_lookup(ht, &key);
52 if (expected && !obj) {
53 pr_warn("Test failed: Could not find key %u\n", key);
55 } else if (!expected && obj) {
56 pr_warn("Test failed: Unexpected entry found for key %u\n",
59 } else if (expected && obj) {
60 if (obj->ptr != TEST_PTR || obj->value != i) {
61 pr_warn("Test failed: Lookup value mismatch %p!=%p, %u!=%u\n",
62 obj->ptr, TEST_PTR, obj->value, i);
71 static void test_bucket_stats(struct rhashtable *ht, bool quiet)
73 unsigned int cnt, rcu_cnt, i, total = 0;
74 struct rhash_head *pos;
76 struct bucket_table *tbl;
78 tbl = rht_dereference_rcu(ht->tbl, ht);
79 for (i = 0; i < tbl->size; i++) {
83 pr_info(" [%#4x/%zu]", i, tbl->size);
85 rht_for_each_entry_rcu(obj, pos, tbl, i, node) {
89 pr_cont(" [%p],", obj);
92 rht_for_each_entry_rcu(obj, pos, tbl, i, node)
96 pr_warn("Test failed: Chain count mismach %d != %d",
100 pr_cont("\n [%#x] first element: %p, chain length: %u\n",
101 i, tbl->buckets[i], cnt);
104 pr_info(" Traversal complete: counted=%u, nelems=%u, entries=%d\n",
105 total, atomic_read(&ht->nelems), TEST_ENTRIES);
107 if (total != atomic_read(&ht->nelems) || total != TEST_ENTRIES)
108 pr_warn("Test failed: Total count mismatch ^^^");
111 static int __init test_rhashtable(struct rhashtable *ht)
113 struct bucket_table *tbl;
114 struct test_obj *obj;
115 struct rhash_head *pos, *next;
121 * Insert TEST_ENTRIES into table with all keys even numbers
123 pr_info(" Adding %d keys\n", TEST_ENTRIES);
124 for (i = 0; i < TEST_ENTRIES; i++) {
125 struct test_obj *obj;
127 obj = kzalloc(sizeof(*obj), GFP_KERNEL);
136 rhashtable_insert(ht, &obj->node);
140 test_bucket_stats(ht, true);
144 for (i = 0; i < TEST_NEXPANDS; i++) {
145 pr_info(" Table expansion iteration %u...\n", i);
146 mutex_lock(&ht->mutex);
147 rhashtable_expand(ht);
148 mutex_unlock(&ht->mutex);
151 pr_info(" Verifying lookups...\n");
156 for (i = 0; i < TEST_NEXPANDS; i++) {
157 pr_info(" Table shrinkage iteration %u...\n", i);
158 mutex_lock(&ht->mutex);
159 rhashtable_shrink(ht);
160 mutex_unlock(&ht->mutex);
163 pr_info(" Verifying lookups...\n");
169 test_bucket_stats(ht, true);
172 pr_info(" Deleting %d keys\n", TEST_ENTRIES);
173 for (i = 0; i < TEST_ENTRIES; i++) {
176 obj = rhashtable_lookup(ht, &key);
179 rhashtable_remove(ht, &obj->node);
186 tbl = rht_dereference_rcu(ht->tbl, ht);
187 for (i = 0; i < tbl->size; i++)
188 rht_for_each_entry_safe(obj, pos, next, tbl, i, node)
194 static int __init test_rht_init(void)
196 struct rhashtable ht;
197 struct rhashtable_params params = {
198 .nelem_hint = TEST_HT_SIZE,
199 .head_offset = offsetof(struct test_obj, node),
200 .key_offset = offsetof(struct test_obj, value),
201 .key_len = sizeof(int),
203 .nulls_base = (3U << RHT_BASE_SHIFT),
204 .grow_decision = rht_grow_above_75,
205 .shrink_decision = rht_shrink_below_30,
209 pr_info("Running resizable hashtable tests...\n");
211 err = rhashtable_init(&ht, ¶ms);
213 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
218 err = test_rhashtable(&ht);
220 rhashtable_destroy(&ht);
225 module_init(test_rht_init);
227 MODULE_LICENSE("GPL v2");