drm_hashtab.c revision 5a0e3ad6af8660be21ca98a971cd00f331318c05 
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#include <linux/slab.h>
39
40int drm_ht_create(struct drm_open_hash *ht, unsigned int order)
41{
42	unsigned int i;
43
44	ht->size = 1 << order;
45	ht->order = order;
46	ht->fill = 0;
47	ht->table = NULL;
48	ht->use_vmalloc = ((ht->size * sizeof(*ht->table)) > PAGE_SIZE);
49	if (!ht->use_vmalloc) {
50		ht->table = kcalloc(ht->size, sizeof(*ht->table), GFP_KERNEL);
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}
65EXPORT_SYMBOL(drm_ht_create);
66
67void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key)
68{
69	struct drm_hash_item *entry;
70	struct hlist_head *h_list;
71	struct hlist_node *list;
72	unsigned int hashed_key;
73	int count = 0;
74
75	hashed_key = hash_long(key, ht->order);
76	DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
77	h_list = &ht->table[hashed_key];
78	hlist_for_each(list, h_list) {
79		entry = hlist_entry(list, struct drm_hash_item, head);
80		DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
81	}
82}
83
84static struct hlist_node *drm_ht_find_key(struct drm_open_hash *ht,
85					  unsigned long key)
86{
87	struct drm_hash_item *entry;
88	struct hlist_head *h_list;
89	struct hlist_node *list;
90	unsigned int hashed_key;
91
92	hashed_key = hash_long(key, ht->order);
93	h_list = &ht->table[hashed_key];
94	hlist_for_each(list, h_list) {
95		entry = hlist_entry(list, struct drm_hash_item, head);
96		if (entry->key == key)
97			return list;
98		if (entry->key > key)
99			break;
100	}
101	return NULL;
102}
103
104
105int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
106{
107	struct drm_hash_item *entry;
108	struct hlist_head *h_list;
109	struct hlist_node *list, *parent;
110	unsigned int hashed_key;
111	unsigned long key = item->key;
112
113	hashed_key = hash_long(key, ht->order);
114	h_list = &ht->table[hashed_key];
115	parent = NULL;
116	hlist_for_each(list, h_list) {
117		entry = hlist_entry(list, struct drm_hash_item, head);
118		if (entry->key == key)
119			return -EINVAL;
120		if (entry->key > key)
121			break;
122		parent = list;
123	}
124	if (parent) {
125		hlist_add_after(parent, &item->head);
126	} else {
127		hlist_add_head(&item->head, h_list);
128	}
129	return 0;
130}
131EXPORT_SYMBOL(drm_ht_insert_item);
132
133/*
134 * Just insert an item and return any "bits" bit key that hasn't been
135 * used before.
136 */
137int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
138			      unsigned long seed, int bits, int shift,
139			      unsigned long add)
140{
141	int ret;
142	unsigned long mask = (1 << bits) - 1;
143	unsigned long first, unshifted_key;
144
145	unshifted_key = hash_long(seed, bits);
146	first = unshifted_key;
147	do {
148		item->key = (unshifted_key << shift) + add;
149		ret = drm_ht_insert_item(ht, item);
150		if (ret)
151			unshifted_key = (unshifted_key + 1) & mask;
152	} while(ret && (unshifted_key != first));
153
154	if (ret) {
155		DRM_ERROR("Available key bit space exhausted\n");
156		return -EINVAL;
157	}
158	return 0;
159}
160EXPORT_SYMBOL(drm_ht_just_insert_please);
161
162int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key,
163		     struct drm_hash_item **item)
164{
165	struct hlist_node *list;
166
167	list = drm_ht_find_key(ht, key);
168	if (!list)
169		return -EINVAL;
170
171	*item = hlist_entry(list, struct drm_hash_item, head);
172	return 0;
173}
174EXPORT_SYMBOL(drm_ht_find_item);
175
176int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key)
177{
178	struct hlist_node *list;
179
180	list = drm_ht_find_key(ht, key);
181	if (list) {
182		hlist_del_init(list);
183		ht->fill--;
184		return 0;
185	}
186	return -EINVAL;
187}
188
189int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
190{
191	hlist_del_init(&item->head);
192	ht->fill--;
193	return 0;
194}
195EXPORT_SYMBOL(drm_ht_remove_item);
196
197void drm_ht_remove(struct drm_open_hash *ht)
198{
199	if (ht->table) {
200		if (ht->use_vmalloc)
201			vfree(ht->table);
202		else
203			kfree(ht->table);
204		ht->table = NULL;
205	}
206}
207EXPORT_SYMBOL(drm_ht_remove);
208