sys/dev/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 <drm/drmP.h>
  36 #include <drm/drm_hashtab.h>
  37 #include <linux/hash.h>
  38 #include <linux/slab.h>
  39 #include <linux/export.h>
  40
  41 int drm_ht_create(struct drm_open_hash *ht, unsigned int order)
  42 {
  43         unsigned int size = 1 << order;
  44
  45         ht->order = order;
  46         ht->table = NULL;
  47         if (size <= PAGE_SIZE / sizeof(*ht->table))
  48                 ht->table = kcalloc(size, sizeof(*ht->table), GFP_KERNEL);
  49         else
  50                 ht->table = kcalloc(size, sizeof(*ht->table), GFP_KERNEL);
  51         if (!ht->table) {
  52                 DRM_ERROR("Out of memory for hash table\n");
  53                 return -ENOMEM;
  54         }
  55         return 0;
  56 }
  57 EXPORT_SYMBOL(drm_ht_create);
  58
  59 void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key)
  60 {
  61         struct drm_hash_item *entry;
  62         struct hlist_head *h_list;
  63         unsigned int hashed_key;
  64         int count = 0;
  65
  66         hashed_key = hash_long(key, ht->order);
  67         DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
  68         h_list = &ht->table[hashed_key];
  69         hlist_for_each_entry(entry, h_list, head)
  70                 DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
  71 }
  72
  73 static struct hlist_node *drm_ht_find_key(struct drm_open_hash *ht,
  74                                           unsigned long key)
  75 {
  76         struct drm_hash_item *entry;
  77         struct hlist_head *h_list;
  78         unsigned int hashed_key;
  79
  80         hashed_key = hash_long(key, ht->order);
  81         h_list = &ht->table[hashed_key];
  82         hlist_for_each_entry(entry, h_list, head) {
  83                 if (entry->key == key)
  84                         return &entry->head;
  85                 if (entry->key > key)
  86                         break;
  87         }
  88         return NULL;
  89 }
  90
  91 static struct hlist_node *drm_ht_find_key_rcu(struct drm_open_hash *ht,
  92                                               unsigned long key)
  93 {
  94         struct drm_hash_item *entry;
  95         struct hlist_head *h_list;
  96         unsigned int hashed_key;
  97
  98         hashed_key = hash_long(key, ht->order);
  99         h_list = &ht->table[hashed_key];
 100         hlist_for_each_entry_rcu(entry, h_list, head) {
 101                 if (entry->key == key)
 102                         return &entry->head;
 103                 if (entry->key > key)
 104                         break;
 105         }
 106         return NULL;
 107 }
 108
 109 int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
 110 {
 111         struct drm_hash_item *entry;
 112         struct hlist_head *h_list;
 113         struct hlist_node *parent;
 114         unsigned int hashed_key;
 115         unsigned long key = item->key;
 116
 117         hashed_key = hash_long(key, ht->order);
 118         h_list = &ht->table[hashed_key];
 119         parent = NULL;
 120         hlist_for_each_entry(entry, h_list, head) {
 121                 if (entry->key == key)
 122                         return -EINVAL;
 123                 if (entry->key > key)
 124                         break;
 125                 parent = &entry->head;
 126         }
 127         if (parent) {
 128                 hlist_add_behind_rcu(&item->head, parent);
 129         } else {
 130                 hlist_add_head_rcu(&item->head, h_list);
 131         }
 132         return 0;
 133 }
 134 EXPORT_SYMBOL(drm_ht_insert_item);
 135
 136 /*
 137  * Just insert an item and return any "bits" bit key that hasn't been
 138  * used before.
 139  */
 140 int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
 141                               unsigned long seed, int bits, int shift,
 142                               unsigned long add)
 143 {
 144         int ret;
 145         unsigned long mask = (1UL << bits) - 1;
 146         unsigned long first, unshifted_key;
 147
 148         unshifted_key = hash_long(seed, bits);
 149         first = unshifted_key;
 150         do {
 151                 item->key = (unshifted_key << shift) + add;
 152                 ret = drm_ht_insert_item(ht, item);
 153                 if (ret)
 154                         unshifted_key = (unshifted_key + 1) & mask;
 155         } while(ret && (unshifted_key != first));
 156
 157         if (ret) {
 158                 DRM_ERROR("Available key bit space exhausted\n");
 159                 return -EINVAL;
 160         }
 161         return 0;
 162 }
 163 EXPORT_SYMBOL(drm_ht_just_insert_please);
 164
 165 int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key,
 166                      struct drm_hash_item **item)
 167 {
 168         struct hlist_node *list;
 169
 170         list = drm_ht_find_key_rcu(ht, key);
 171         if (!list)
 172                 return -EINVAL;
 173
 174         *item = hlist_entry(list, struct drm_hash_item, head);
 175         return 0;
 176 }
 177 EXPORT_SYMBOL(drm_ht_find_item);
 178
 179 int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key)
 180 {
 181         struct hlist_node *list;
 182
 183         list = drm_ht_find_key(ht, key);
 184         if (list) {
 185                 hlist_del_init_rcu(list);
 186                 return 0;
 187         }
 188         return -EINVAL;
 189 }
 190
 191 int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
 192 {
 193         hlist_del_init_rcu(&item->head);
 194         return 0;
 195 }
 196 EXPORT_SYMBOL(drm_ht_remove_item);
 197
 198 void drm_ht_remove(struct drm_open_hash *ht)
 199 {
 200         if (ht->table) {
 201                 if ((PAGE_SIZE / sizeof(*ht->table)) >> ht->order)
 202                         kfree(ht->table);
 203                 else
 204                         kfree(ht->table);
 205                 ht->table = NULL;
 206         }
 207 }
 208 EXPORT_SYMBOL(drm_ht_remove);