LXR linux/security/selinux/ss/hashtab.c

   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 <linux/sched.h>
  11#include "hashtab.h"
  12
  13static struct kmem_cache *hashtab_node_cachep;
  14
  15struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
  16                               int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
  17                               u32 size)
  18{
  19        struct hashtab *p;
  20        u32 i;
  21
  22        p = kzalloc(sizeof(*p), GFP_KERNEL);
  23        if (!p)
  24                return p;
  25
  26        p->size = size;
  27        p->nel = 0;
  28        p->hash_value = hash_value;
  29        p->keycmp = keycmp;
  30        p->htable = kmalloc_array(size, sizeof(*p->htable), GFP_KERNEL);
  31        if (!p->htable) {
  32                kfree(p);
  33                return NULL;
  34        }
  35
  36        for (i = 0; i < size; i++)
  37                p->htable[i] = NULL;
  38
  39        return p;
  40}
  41
  42int hashtab_insert(struct hashtab *h, void *key, void *datum)
  43{
  44        u32 hvalue;
  45        struct hashtab_node *prev, *cur, *newnode;
  46
  47        cond_resched();
  48
  49        if (!h || h->nel == HASHTAB_MAX_NODES)
  50                return -EINVAL;
  51
  52        hvalue = h->hash_value(h, key);
  53        prev = NULL;
  54        cur = h->htable[hvalue];
  55        while (cur && h->keycmp(h, key, cur->key) > 0) {
  56                prev = cur;
  57                cur = cur->next;
  58        }
  59
  60        if (cur && (h->keycmp(h, key, cur->key) == 0))
  61                return -EEXIST;
  62
  63        newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
  64        if (!newnode)
  65                return -ENOMEM;
  66        newnode->key = key;
  67        newnode->datum = datum;
  68        if (prev) {
  69                newnode->next = prev->next;
  70                prev->next = newnode;
  71        } else {
  72                newnode->next = h->htable[hvalue];
  73                h->htable[hvalue] = newnode;
  74        }
  75
  76        h->nel++;
  77        return 0;
  78}
  79
  80void *hashtab_search(struct hashtab *h, const void *key)
  81{
  82        u32 hvalue;
  83        struct hashtab_node *cur;
  84
  85        if (!h)
  86                return NULL;
  87
  88        hvalue = h->hash_value(h, key);
  89        cur = h->htable[hvalue];
  90        while (cur && h->keycmp(h, key, cur->key) > 0)
  91                cur = cur->next;
  92
  93        if (!cur || (h->keycmp(h, key, cur->key) != 0))
  94                return NULL;
  95
  96        return cur->datum;
  97}
  98
  99void hashtab_destroy(struct hashtab *h)
 100{
 101        u32 i;
 102        struct hashtab_node *cur, *temp;
 103
 104        if (!h)
 105                return;
 106
 107        for (i = 0; i < h->size; i++) {
 108                cur = h->htable[i];
 109                while (cur) {
 110                        temp = cur;
 111                        cur = cur->next;
 112                        kmem_cache_free(hashtab_node_cachep, temp);
 113                }
 114                h->htable[i] = NULL;
 115        }
 116
 117        kfree(h->htable);
 118        h->htable = NULL;
 119
 120        kfree(h);
 121}
 122
 123int hashtab_map(struct hashtab *h,
 124                int (*apply)(void *k, void *d, void *args),
 125                void *args)
 126{
 127        u32 i;
 128        int ret;
 129        struct hashtab_node *cur;
 130
 131        if (!h)
 132                return 0;
 133
 134        for (i = 0; i < h->size; i++) {
 135                cur = h->htable[i];
 136                while (cur) {
 137                        ret = apply(cur->key, cur->datum, args);
 138                        if (ret)
 139                                return ret;
 140                        cur = cur->next;
 141                }
 142        }
 143        return 0;
 144}
 145
 146
 147void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
 148{
 149        u32 i, chain_len, slots_used, max_chain_len;
 150        struct hashtab_node *cur;
 151
 152        slots_used = 0;
 153        max_chain_len = 0;
 154        for (i = 0; i < h->size; i++) {
 155                cur = h->htable[i];
 156                if (cur) {
 157                        slots_used++;
 158                        chain_len = 0;
 159                        while (cur) {
 160                                chain_len++;
 161                                cur = cur->next;
 162                        }
 163
 164                        if (chain_len > max_chain_len)
 165                                max_chain_len = chain_len;
 166                }
 167        }
 168
 169        info->slots_used = slots_used;
 170        info->max_chain_len = max_chain_len;
 171}
 172
 173void __init hashtab_cache_init(void)
 174{
 175                hashtab_node_cachep = kmem_cache_create("hashtab_node",
 176                        sizeof(struct hashtab_node),
 177                        0, SLAB_PANIC, NULL);
 178}
 179