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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the hash table type.
4 *
5 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
6 */
7#include <linux/kernel.h>
8#include <linux/slab.h>
9#include <linux/errno.h>
10#include "hashtab.h"
11
12static struct kmem_cache *hashtab_node_cachep __ro_after_init;
13
14/*
15 * Here we simply round the number of elements up to the nearest power of two.
16 * I tried also other options like rounding down or rounding to the closest
17 * power of two (up or down based on which is closer), but I was unable to
18 * find any significant difference in lookup/insert performance that would
19 * justify switching to a different (less intuitive) formula. It could be that
20 * a different formula is actually more optimal, but any future changes here
21 * should be supported with performance/memory usage data.
22 *
23 * The total memory used by the htable arrays (only) with Fedora policy loaded
24 * is approximately 163 KB at the time of writing.
25 */
26static u32 hashtab_compute_size(u32 nel)
27{
28 return nel == 0 ? 0 : roundup_pow_of_two(nel);
29}
30
31int hashtab_init(struct hashtab *h, u32 nel_hint)
32{
33 h->size = hashtab_compute_size(nel_hint);
34 h->nel = 0;
35 if (!h->size)
36 return 0;
37
38 h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL);
39 return h->htable ? 0 : -ENOMEM;
40}
41
42int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
43 void *key, void *datum)
44{
45 struct hashtab_node *newnode;
46
47 newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
48 if (!newnode)
49 return -ENOMEM;
50 newnode->key = key;
51 newnode->datum = datum;
52 newnode->next = *dst;
53 *dst = newnode;
54
55 h->nel++;
56 return 0;
57}
58
59void hashtab_destroy(struct hashtab *h)
60{
61 u32 i;
62 struct hashtab_node *cur, *temp;
63
64 for (i = 0; i < h->size; i++) {
65 cur = h->htable[i];
66 while (cur) {
67 temp = cur;
68 cur = cur->next;
69 kmem_cache_free(hashtab_node_cachep, temp);
70 }
71 h->htable[i] = NULL;
72 }
73
74 kfree(h->htable);
75 h->htable = NULL;
76}
77
78int hashtab_map(struct hashtab *h,
79 int (*apply)(void *k, void *d, void *args),
80 void *args)
81{
82 u32 i;
83 int ret;
84 struct hashtab_node *cur;
85
86 for (i = 0; i < h->size; i++) {
87 cur = h->htable[i];
88 while (cur) {
89 ret = apply(cur->key, cur->datum, args);
90 if (ret)
91 return ret;
92 cur = cur->next;
93 }
94 }
95 return 0;
96}
97
98
99void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
100{
101 u32 i, chain_len, slots_used, max_chain_len;
102 struct hashtab_node *cur;
103
104 slots_used = 0;
105 max_chain_len = 0;
106 for (i = 0; i < h->size; i++) {
107 cur = h->htable[i];
108 if (cur) {
109 slots_used++;
110 chain_len = 0;
111 while (cur) {
112 chain_len++;
113 cur = cur->next;
114 }
115
116 if (chain_len > max_chain_len)
117 max_chain_len = chain_len;
118 }
119 }
120
121 info->slots_used = slots_used;
122 info->max_chain_len = max_chain_len;
123}
124
125int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
126 int (*copy)(struct hashtab_node *new,
127 struct hashtab_node *orig, void *args),
128 int (*destroy)(void *k, void *d, void *args),
129 void *args)
130{
131 struct hashtab_node *cur, *tmp, *tail;
132 int i, rc;
133
134 memset(new, 0, sizeof(*new));
135
136 new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
137 if (!new->htable)
138 return -ENOMEM;
139
140 new->size = orig->size;
141
142 for (i = 0; i < orig->size; i++) {
143 tail = NULL;
144 for (cur = orig->htable[i]; cur; cur = cur->next) {
145 tmp = kmem_cache_zalloc(hashtab_node_cachep,
146 GFP_KERNEL);
147 if (!tmp)
148 goto error;
149 rc = copy(tmp, cur, args);
150 if (rc) {
151 kmem_cache_free(hashtab_node_cachep, tmp);
152 goto error;
153 }
154 tmp->next = NULL;
155 if (!tail)
156 new->htable[i] = tmp;
157 else
158 tail->next = tmp;
159 tail = tmp;
160 new->nel++;
161 }
162 }
163
164 return 0;
165
166 error:
167 for (i = 0; i < new->size; i++) {
168 for (cur = new->htable[i]; cur; cur = tmp) {
169 tmp = cur->next;
170 destroy(cur->key, cur->datum, args);
171 kmem_cache_free(hashtab_node_cachep, cur);
172 }
173 }
174 kmem_cache_free(hashtab_node_cachep, new);
175 return -ENOMEM;
176}
177
178void __init hashtab_cache_init(void)
179{
180 hashtab_node_cachep = kmem_cache_create("hashtab_node",
181 sizeof(struct hashtab_node),
182 0, SLAB_PANIC, NULL);
183}
1/*
2 * Implementation of the hash table type.
3 *
4 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
5 */
6#include <linux/kernel.h>
7#include <linux/slab.h>
8#include <linux/errno.h>
9#include <linux/sched.h>
10#include "hashtab.h"
11
12struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
13 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
14 u32 size)
15{
16 struct hashtab *p;
17 u32 i;
18
19 p = kzalloc(sizeof(*p), GFP_KERNEL);
20 if (p == NULL)
21 return p;
22
23 p->size = size;
24 p->nel = 0;
25 p->hash_value = hash_value;
26 p->keycmp = keycmp;
27 p->htable = kmalloc(sizeof(*(p->htable)) * size, GFP_KERNEL);
28 if (p->htable == NULL) {
29 kfree(p);
30 return NULL;
31 }
32
33 for (i = 0; i < size; i++)
34 p->htable[i] = NULL;
35
36 return p;
37}
38
39int hashtab_insert(struct hashtab *h, void *key, void *datum)
40{
41 u32 hvalue;
42 struct hashtab_node *prev, *cur, *newnode;
43
44 cond_resched();
45
46 if (!h || h->nel == HASHTAB_MAX_NODES)
47 return -EINVAL;
48
49 hvalue = h->hash_value(h, key);
50 prev = NULL;
51 cur = h->htable[hvalue];
52 while (cur && h->keycmp(h, key, cur->key) > 0) {
53 prev = cur;
54 cur = cur->next;
55 }
56
57 if (cur && (h->keycmp(h, key, cur->key) == 0))
58 return -EEXIST;
59
60 newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
61 if (newnode == NULL)
62 return -ENOMEM;
63 newnode->key = key;
64 newnode->datum = datum;
65 if (prev) {
66 newnode->next = prev->next;
67 prev->next = newnode;
68 } else {
69 newnode->next = h->htable[hvalue];
70 h->htable[hvalue] = newnode;
71 }
72
73 h->nel++;
74 return 0;
75}
76
77void *hashtab_search(struct hashtab *h, const void *key)
78{
79 u32 hvalue;
80 struct hashtab_node *cur;
81
82 if (!h)
83 return NULL;
84
85 hvalue = h->hash_value(h, key);
86 cur = h->htable[hvalue];
87 while (cur && h->keycmp(h, key, cur->key) > 0)
88 cur = cur->next;
89
90 if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
91 return NULL;
92
93 return cur->datum;
94}
95
96void hashtab_destroy(struct hashtab *h)
97{
98 u32 i;
99 struct hashtab_node *cur, *temp;
100
101 if (!h)
102 return;
103
104 for (i = 0; i < h->size; i++) {
105 cur = h->htable[i];
106 while (cur) {
107 temp = cur;
108 cur = cur->next;
109 kfree(temp);
110 }
111 h->htable[i] = NULL;
112 }
113
114 kfree(h->htable);
115 h->htable = NULL;
116
117 kfree(h);
118}
119
120int hashtab_map(struct hashtab *h,
121 int (*apply)(void *k, void *d, void *args),
122 void *args)
123{
124 u32 i;
125 int ret;
126 struct hashtab_node *cur;
127
128 if (!h)
129 return 0;
130
131 for (i = 0; i < h->size; i++) {
132 cur = h->htable[i];
133 while (cur) {
134 ret = apply(cur->key, cur->datum, args);
135 if (ret)
136 return ret;
137 cur = cur->next;
138 }
139 }
140 return 0;
141}
142
143
144void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
145{
146 u32 i, chain_len, slots_used, max_chain_len;
147 struct hashtab_node *cur;
148
149 slots_used = 0;
150 max_chain_len = 0;
151 for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
152 cur = h->htable[i];
153 if (cur) {
154 slots_used++;
155 chain_len = 0;
156 while (cur) {
157 chain_len++;
158 cur = cur->next;
159 }
160
161 if (chain_len > max_chain_len)
162 max_chain_len = chain_len;
163 }
164 }
165
166 info->slots_used = slots_used;
167 info->max_chain_len = max_chain_len;
168}