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