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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#include "security.h"
12
13static struct kmem_cache *hashtab_node_cachep __ro_after_init;
14
15/*
16 * Here we simply round the number of elements up to the nearest power of two.
17 * I tried also other options like rounding down or rounding to the closest
18 * power of two (up or down based on which is closer), but I was unable to
19 * find any significant difference in lookup/insert performance that would
20 * justify switching to a different (less intuitive) formula. It could be that
21 * a different formula is actually more optimal, but any future changes here
22 * should be supported with performance/memory usage data.
23 *
24 * The total memory used by the htable arrays (only) with Fedora policy loaded
25 * is approximately 163 KB at the time of writing.
26 */
27static u32 hashtab_compute_size(u32 nel)
28{
29 return nel == 0 ? 0 : roundup_pow_of_two(nel);
30}
31
32int hashtab_init(struct hashtab *h, u32 nel_hint)
33{
34 u32 size = hashtab_compute_size(nel_hint);
35
36 /* should already be zeroed, but better be safe */
37 h->nel = 0;
38 h->size = 0;
39 h->htable = NULL;
40
41 if (size) {
42 h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
43 if (!h->htable)
44 return -ENOMEM;
45 h->size = size;
46 }
47 return 0;
48}
49
50int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
51 void *key, void *datum)
52{
53 struct hashtab_node *newnode;
54
55 newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
56 if (!newnode)
57 return -ENOMEM;
58 newnode->key = key;
59 newnode->datum = datum;
60 newnode->next = *dst;
61 *dst = newnode;
62
63 h->nel++;
64 return 0;
65}
66
67void hashtab_destroy(struct hashtab *h)
68{
69 u32 i;
70 struct hashtab_node *cur, *temp;
71
72 for (i = 0; i < h->size; i++) {
73 cur = h->htable[i];
74 while (cur) {
75 temp = cur;
76 cur = cur->next;
77 kmem_cache_free(hashtab_node_cachep, temp);
78 }
79 h->htable[i] = NULL;
80 }
81
82 kfree(h->htable);
83 h->htable = NULL;
84}
85
86int hashtab_map(struct hashtab *h,
87 int (*apply)(void *k, void *d, void *args),
88 void *args)
89{
90 u32 i;
91 int ret;
92 struct hashtab_node *cur;
93
94 for (i = 0; i < h->size; i++) {
95 cur = h->htable[i];
96 while (cur) {
97 ret = apply(cur->key, cur->datum, args);
98 if (ret)
99 return ret;
100 cur = cur->next;
101 }
102 }
103 return 0;
104}
105
106
107void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
108{
109 u32 i, chain_len, slots_used, max_chain_len;
110 struct hashtab_node *cur;
111
112 slots_used = 0;
113 max_chain_len = 0;
114 for (i = 0; i < h->size; i++) {
115 cur = h->htable[i];
116 if (cur) {
117 slots_used++;
118 chain_len = 0;
119 while (cur) {
120 chain_len++;
121 cur = cur->next;
122 }
123
124 if (chain_len > max_chain_len)
125 max_chain_len = chain_len;
126 }
127 }
128
129 info->slots_used = slots_used;
130 info->max_chain_len = max_chain_len;
131}
132
133int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
134 int (*copy)(struct hashtab_node *new,
135 struct hashtab_node *orig, void *args),
136 int (*destroy)(void *k, void *d, void *args),
137 void *args)
138{
139 struct hashtab_node *cur, *tmp, *tail;
140 int i, rc;
141
142 memset(new, 0, sizeof(*new));
143
144 new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
145 if (!new->htable)
146 return -ENOMEM;
147
148 new->size = orig->size;
149
150 for (i = 0; i < orig->size; i++) {
151 tail = NULL;
152 for (cur = orig->htable[i]; cur; cur = cur->next) {
153 tmp = kmem_cache_zalloc(hashtab_node_cachep,
154 GFP_KERNEL);
155 if (!tmp)
156 goto error;
157 rc = copy(tmp, cur, args);
158 if (rc) {
159 kmem_cache_free(hashtab_node_cachep, tmp);
160 goto error;
161 }
162 tmp->next = NULL;
163 if (!tail)
164 new->htable[i] = tmp;
165 else
166 tail->next = tmp;
167 tail = tmp;
168 new->nel++;
169 }
170 }
171
172 return 0;
173
174 error:
175 for (i = 0; i < new->size; i++) {
176 for (cur = new->htable[i]; cur; cur = tmp) {
177 tmp = cur->next;
178 destroy(cur->key, cur->datum, args);
179 kmem_cache_free(hashtab_node_cachep, cur);
180 }
181 }
182 kfree(new->htable);
183 memset(new, 0, sizeof(*new));
184 return -ENOMEM;
185}
186
187void __init hashtab_cache_init(void)
188{
189 hashtab_node_cachep = kmem_cache_create("hashtab_node",
190 sizeof(struct hashtab_node),
191 0, SLAB_PANIC, NULL);
192}
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;
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 rouding 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
125void __init hashtab_cache_init(void)
126{
127 hashtab_node_cachep = kmem_cache_create("hashtab_node",
128 sizeof(struct hashtab_node),
129 0, SLAB_PANIC, NULL);
130}