drivers/char/drm/drm_hashtab.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND. USA.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  *
  27  **************************************************************************/
  28 /*
  29  * Simple open hash tab implementation.
  30  *
  31  * Authors:
  32  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  33  */
  34
  35 #include "drmP.h"
  36 #include "drm_hashtab.h"
  37 #include <linux/hash.h>
  38
  39 int drm_ht_create(drm_open_hash_t *ht, unsigned int order)
  40 {
  41         unsigned int i;
  42
  43         ht->size = 1 << order;
  44         ht->order = order;
  45         ht->fill = 0;
  46         ht->table = vmalloc(ht->size*sizeof(*ht->table));
  47         if (!ht->table) {
  48                 DRM_ERROR("Out of memory for hash table\n");
  49                 return -ENOMEM;
  50         }
  51         for (i=0; i< ht->size; ++i) {
  52                 INIT_HLIST_HEAD(&ht->table[i]);
  53         }
  54         return 0;
  55 }
  56
  57 void drm_ht_verbose_list(drm_open_hash_t *ht, unsigned long key)
  58 {
  59         drm_hash_item_t *entry;
  60         struct hlist_head *h_list;
  61         struct hlist_node *list;
  62         unsigned int hashed_key;
  63         int count = 0;
  64
  65         hashed_key = hash_long(key, ht->order);
  66         DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
  67         h_list = &ht->table[hashed_key];
  68         hlist_for_each(list, h_list) {
  69                 entry = hlist_entry(list, drm_hash_item_t, head);
  70                 DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
  71         }
  72 }
  73
  74 static struct hlist_node *drm_ht_find_key(drm_open_hash_t *ht,
  75                                           unsigned long key)
  76 {
  77         drm_hash_item_t *entry;
  78         struct hlist_head *h_list;
  79         struct hlist_node *list;
  80         unsigned int hashed_key;
  81
  82         hashed_key = hash_long(key, ht->order);
  83         h_list = &ht->table[hashed_key];
  84         hlist_for_each(list, h_list) {
  85                 entry = hlist_entry(list, drm_hash_item_t, head);
  86                 if (entry->key == key)
  87                         return list;
  88                 if (entry->key > key)
  89                         break;
  90         }
  91         return NULL;
  92 }
  93
  94
  95 int drm_ht_insert_item(drm_open_hash_t *ht, drm_hash_item_t *item)
  96 {
  97         drm_hash_item_t *entry;
  98         struct hlist_head *h_list;
  99         struct hlist_node *list, *parent;
 100         unsigned int hashed_key;
 101         unsigned long key = item->key;
 102
 103         hashed_key = hash_long(key, ht->order);
 104         h_list = &ht->table[hashed_key];
 105         parent = NULL;
 106         hlist_for_each(list, h_list) {
 107                 entry = hlist_entry(list, drm_hash_item_t, head);
 108                 if (entry->key == key)
 109                         return -EINVAL;
 110                 if (entry->key > key)
 111                         break;
 112                 parent = list;
 113         }
 114         if (parent) {
 115                 hlist_add_after(parent, &item->head);
 116         } else {
 117                 hlist_add_head(&item->head, h_list);
 118         }
 119         return 0;
 120 }
 121
 122 /*
 123  * Just insert an item and return any "bits" bit key that hasn't been
 124  * used before.
 125  */
 126 int drm_ht_just_insert_please(drm_open_hash_t *ht, drm_hash_item_t *item,
 127                               unsigned long seed, int bits, int shift,
 128                               unsigned long add)
 129 {
 130         int ret;
 131         unsigned long mask = (1 << bits) - 1;
 132         unsigned long first, unshifted_key;
 133
 134         unshifted_key = hash_long(seed, bits);
 135         first = unshifted_key;
 136         do {
 137                 item->key = (unshifted_key << shift) + add;
 138                 ret = drm_ht_insert_item(ht, item);
 139                 if (ret)
 140                         unshifted_key = (unshifted_key + 1) & mask;
 141         } while(ret && (unshifted_key != first));
 142
 143         if (ret) {
 144                 DRM_ERROR("Available key bit space exhausted\n");
 145                 return -EINVAL;
 146         }
 147         return 0;
 148 }
 149
 150 int drm_ht_find_item(drm_open_hash_t *ht, unsigned long key,
 151                      drm_hash_item_t **item)
 152 {
 153         struct hlist_node *list;
 154
 155         list = drm_ht_find_key(ht, key);
 156         if (!list)
 157                 return -EINVAL;
 158
 159         *item = hlist_entry(list, drm_hash_item_t, head);
 160         return 0;
 161 }
 162
 163 int drm_ht_remove_key(drm_open_hash_t *ht, unsigned long key)
 164 {
 165         struct hlist_node *list;
 166
 167         list = drm_ht_find_key(ht, key);
 168         if (list) {
 169                 hlist_del_init(list);
 170                 ht->fill--;
 171                 return 0;
 172         }
 173         return -EINVAL;
 174 }
 175
 176 int drm_ht_remove_item(drm_open_hash_t *ht, drm_hash_item_t *item)
 177 {
 178         hlist_del_init(&item->head);
 179         ht->fill--;
 180         return 0;
 181 }
 182
 183 void drm_ht_remove(drm_open_hash_t *ht)
 184 {
 185         if (ht->table) {
 186                 vfree(ht->table);
 187                 ht->table = NULL;
 188         }
 189 }
 190