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 = NULL;
  47         ht->use_vmalloc = ((ht->size * sizeof(*ht->table)) > PAGE_SIZE);
  48         if (!ht->use_vmalloc) {
  49                 ht->table = drm_calloc(ht->size, sizeof(*ht->table),
  50                                        DRM_MEM_HASHTAB);
  51         }
  52         if (!ht->table) {
  53                 ht->use_vmalloc = 1;
  54                 ht->table = vmalloc(ht->size*sizeof(*ht->table));
  55         }
  56         if (!ht->table) {
  57                 DRM_ERROR("Out of memory for hash table\n");
  58                 return -ENOMEM;
  59         }
  60         for (i=0; i< ht->size; ++i) {
  61                 INIT_HLIST_HEAD(&ht->table[i]);
  62         }
  63         return 0;
  64 }
  65
  66 void drm_ht_verbose_list(drm_open_hash_t *ht, unsigned long key)
  67 {
  68         drm_hash_item_t *entry;
  69         struct hlist_head *h_list;
  70         struct hlist_node *list;
  71         unsigned int hashed_key;
  72         int count = 0;
  73
  74         hashed_key = hash_long(key, ht->order);
  75         DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
  76         h_list = &ht->table[hashed_key];
  77         hlist_for_each(list, h_list) {
  78                 entry = hlist_entry(list, drm_hash_item_t, head);
  79                 DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
  80         }
  81 }
  82
  83 static struct hlist_node *drm_ht_find_key(drm_open_hash_t *ht,
  84                                           unsigned long key)
  85 {
  86         drm_hash_item_t *entry;
  87         struct hlist_head *h_list;
  88         struct hlist_node *list;
  89         unsigned int hashed_key;
  90
  91         hashed_key = hash_long(key, ht->order);
  92         h_list = &ht->table[hashed_key];
  93         hlist_for_each(list, h_list) {
  94                 entry = hlist_entry(list, drm_hash_item_t, head);
  95                 if (entry->key == key)
  96                         return list;
  97                 if (entry->key > key)
  98                         break;
  99         }
 100         return NULL;
 101 }
 102
 103
 104 int drm_ht_insert_item(drm_open_hash_t *ht, drm_hash_item_t *item)
 105 {
 106         drm_hash_item_t *entry;
 107         struct hlist_head *h_list;
 108         struct hlist_node *list, *parent;
 109         unsigned int hashed_key;
 110         unsigned long key = item->key;
 111
 112         hashed_key = hash_long(key, ht->order);
 113         h_list = &ht->table[hashed_key];
 114         parent = NULL;
 115         hlist_for_each(list, h_list) {
 116                 entry = hlist_entry(list, drm_hash_item_t, head);
 117                 if (entry->key == key)
 118                         return -EINVAL;
 119                 if (entry->key > key)
 120                         break;
 121                 parent = list;
 122         }
 123         if (parent) {
 124                 hlist_add_after(parent, &item->head);
 125         } else {
 126                 hlist_add_head(&item->head, h_list);
 127         }
 128         return 0;
 129 }
 130
 131 /*
 132  * Just insert an item and return any "bits" bit key that hasn't been
 133  * used before.
 134  */
 135 int drm_ht_just_insert_please(drm_open_hash_t *ht, drm_hash_item_t *item,
 136                               unsigned long seed, int bits, int shift,
 137                               unsigned long add)
 138 {
 139         int ret;
 140         unsigned long mask = (1 << bits) - 1;
 141         unsigned long first, unshifted_key;
 142
 143         unshifted_key = hash_long(seed, bits);
 144         first = unshifted_key;
 145         do {
 146                 item->key = (unshifted_key << shift) + add;
 147                 ret = drm_ht_insert_item(ht, item);
 148                 if (ret)
 149                         unshifted_key = (unshifted_key + 1) & mask;
 150         } while(ret && (unshifted_key != first));
 151
 152         if (ret) {
 153                 DRM_ERROR("Available key bit space exhausted\n");
 154                 return -EINVAL;
 155         }
 156         return 0;
 157 }
 158
 159 int drm_ht_find_item(drm_open_hash_t *ht, unsigned long key,
 160                      drm_hash_item_t **item)
 161 {
 162         struct hlist_node *list;
 163
 164         list = drm_ht_find_key(ht, key);
 165         if (!list)
 166                 return -EINVAL;
 167
 168         *item = hlist_entry(list, drm_hash_item_t, head);
 169         return 0;
 170 }
 171
 172 int drm_ht_remove_key(drm_open_hash_t *ht, unsigned long key)
 173 {
 174         struct hlist_node *list;
 175
 176         list = drm_ht_find_key(ht, key);
 177         if (list) {
 178                 hlist_del_init(list);
 179                 ht->fill--;
 180                 return 0;
 181         }
 182         return -EINVAL;
 183 }
 184
 185 int drm_ht_remove_item(drm_open_hash_t *ht, drm_hash_item_t *item)
 186 {
 187         hlist_del_init(&item->head);
 188         ht->fill--;
 189         return 0;
 190 }
 191
 192 void drm_ht_remove(drm_open_hash_t *ht)
 193 {
 194         if (ht->table) {
 195                 if (ht->use_vmalloc)
 196                         vfree(ht->table);
 197                 else
 198                         drm_free(ht->table, ht->size * sizeof(*ht->table),
 199                                  DRM_MEM_HASHTAB);
 200                 ht->table = NULL;
 201         }
 202 }
 203