drivers/staging/batman-adv/hash.c

   1 /*
   2  * Copyright (C) 2006-2010 B.A.T.M.A.N. contributors:
   3  *
   4  * Simon Wunderlich, Marek Lindner
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #include "main.h"
  23 #include "hash.h"
  24
  25 /* clears the hash */
  26 static void hash_init(struct hashtable_t *hash)
  27 {
  28         int i;
  29
  30         hash->elements = 0;
  31
  32         for (i = 0 ; i < hash->size; i++)
  33                 hash->table[i] = NULL;
  34 }
  35
  36 /* free only the hashtable and the hash itself. */
  37 void hash_destroy(struct hashtable_t *hash)
  38 {
  39         kfree(hash->table);
  40         kfree(hash);
  41 }
  42
  43 /* allocates and clears the hash */
  44 struct hashtable_t *hash_new(int size)
  45 {
  46         struct hashtable_t *hash;
  47
  48         hash = kmalloc(sizeof(struct hashtable_t) , GFP_ATOMIC);
  49
  50         if (hash == NULL)
  51                 return NULL;
  52
  53         hash->size = size;
  54         hash->table = kmalloc(sizeof(struct element_t *) * size, GFP_ATOMIC);
  55
  56         if (hash->table == NULL) {
  57                 kfree(hash);
  58                 return NULL;
  59         }
  60
  61         hash_init(hash);
  62
  63         return hash;
  64 }
  65
  66 /* remove bucket (this might be used in hash_iterate() if you already found the
  67  * bucket you want to delete and don't need the overhead to find it again with
  68  * hash_remove(). But usually, you don't want to use this function, as it
  69  * fiddles with hash-internals. */
  70 void *hash_remove_bucket(struct hashtable_t *hash, struct hash_it_t *hash_it_t)
  71 {
  72         void *data_save;
  73
  74         data_save = hash_it_t->bucket->data;
  75
  76         if (hash_it_t->prev_bucket != NULL)
  77                 hash_it_t->prev_bucket->next = hash_it_t->bucket->next;
  78         else if (hash_it_t->first_bucket != NULL)
  79                 (*hash_it_t->first_bucket) = hash_it_t->bucket->next;
  80
  81         kfree(hash_it_t->bucket);
  82         hash->elements--;
  83
  84         return data_save;
  85 }