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
hashtab_create(u32 (* hash_value)(struct hashtab * h,const void * key),int (* keycmp)(struct hashtab * h,const void * key1,const void * key2),u32 size)12 struct 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
hashtab_insert(struct hashtab * h,void * key,void * datum)39 int 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
hashtab_search(struct hashtab * h,const void * key)77 void *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
hashtab_destroy(struct hashtab * h)96 void 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
hashtab_map(struct hashtab * h,int (* apply)(void * k,void * d,void * args),void * args)120 int 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
hashtab_stat(struct hashtab * h,struct hashtab_info * info)144 void 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 }
169