1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
// SPDX-License-Identifier: GPL-2.0
/*
* Implementation of the hash table type.
*
* Author : Stephen Smalley, <sds@tycho.nsa.gov>
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "hashtab.h"
#include "security.h"
static struct kmem_cache *hashtab_node_cachep __ro_after_init;
/*
* Here we simply round the number of elements up to the nearest power of two.
* I tried also other options like rounding down or rounding to the closest
* power of two (up or down based on which is closer), but I was unable to
* find any significant difference in lookup/insert performance that would
* justify switching to a different (less intuitive) formula. It could be that
* a different formula is actually more optimal, but any future changes here
* should be supported with performance/memory usage data.
*
* The total memory used by the htable arrays (only) with Fedora policy loaded
* is approximately 163 KB at the time of writing.
*/
static u32 hashtab_compute_size(u32 nel)
{
return nel == 0 ? 0 : roundup_pow_of_two(nel);
}
int hashtab_init(struct hashtab *h, u32 nel_hint)
{
u32 size = hashtab_compute_size(nel_hint);
/* should already be zeroed, but better be safe */
h->nel = 0;
h->size = 0;
h->htable = NULL;
if (size) {
h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
if (!h->htable)
return -ENOMEM;
h->size = size;
}
return 0;
}
int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
void *key, void *datum)
{
struct hashtab_node *newnode;
newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
if (!newnode)
return -ENOMEM;
newnode->key = key;
newnode->datum = datum;
newnode->next = *dst;
*dst = newnode;
h->nel++;
return 0;
}
void hashtab_destroy(struct hashtab *h)
{
u32 i;
struct hashtab_node *cur, *temp;
for (i = 0; i < h->size; i++) {
cur = h->htable[i];
while (cur) {
temp = cur;
cur = cur->next;
kmem_cache_free(hashtab_node_cachep, temp);
}
h->htable[i] = NULL;
}
kfree(h->htable);
h->htable = NULL;
}
int hashtab_map(struct hashtab *h,
int (*apply)(void *k, void *d, void *args),
void *args)
{
u32 i;
int ret;
struct hashtab_node *cur;
for (i = 0; i < h->size; i++) {
cur = h->htable[i];
while (cur) {
ret = apply(cur->key, cur->datum, args);
if (ret)
return ret;
cur = cur->next;
}
}
return 0;
}
void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
{
u32 i, chain_len, slots_used, max_chain_len;
struct hashtab_node *cur;
slots_used = 0;
max_chain_len = 0;
for (i = 0; i < h->size; i++) {
cur = h->htable[i];
if (cur) {
slots_used++;
chain_len = 0;
while (cur) {
chain_len++;
cur = cur->next;
}
if (chain_len > max_chain_len)
max_chain_len = chain_len;
}
}
info->slots_used = slots_used;
info->max_chain_len = max_chain_len;
}
int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
int (*copy)(struct hashtab_node *new,
struct hashtab_node *orig, void *args),
int (*destroy)(void *k, void *d, void *args),
void *args)
{
struct hashtab_node *cur, *tmp, *tail;
int i, rc;
memset(new, 0, sizeof(*new));
new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
if (!new->htable)
return -ENOMEM;
new->size = orig->size;
for (i = 0; i < orig->size; i++) {
tail = NULL;
for (cur = orig->htable[i]; cur; cur = cur->next) {
tmp = kmem_cache_zalloc(hashtab_node_cachep,
GFP_KERNEL);
if (!tmp)
goto error;
rc = copy(tmp, cur, args);
if (rc) {
kmem_cache_free(hashtab_node_cachep, tmp);
goto error;
}
tmp->next = NULL;
if (!tail)
new->htable[i] = tmp;
else
tail->next = tmp;
tail = tmp;
new->nel++;
}
}
return 0;
error:
for (i = 0; i < new->size; i++) {
for (cur = new->htable[i]; cur; cur = tmp) {
tmp = cur->next;
destroy(cur->key, cur->datum, args);
kmem_cache_free(hashtab_node_cachep, cur);
}
}
kmem_cache_free(hashtab_node_cachep, new);
return -ENOMEM;
}
void __init hashtab_cache_init(void)
{
hashtab_node_cachep = kmem_cache_create("hashtab_node",
sizeof(struct hashtab_node),
0, SLAB_PANIC, NULL);
}
|
