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