linux_idr.c revision 1.7 1 /* $NetBSD: linux_idr.c,v 1.7 2018/08/27 06:55:01 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2013 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: linux_idr.c,v 1.7 2018/08/27 06:55:01 riastradh Exp $");
34
35 #include <sys/param.h>
36 #include <sys/atomic.h>
37 #include <sys/rbtree.h>
38
39 #include <linux/err.h>
40 #include <linux/idr.h>
41 #include <linux/slab.h>
42
43 struct idr_node {
44 rb_node_t in_rb_node;
45 int in_index;
46 void *in_data;
47 SIMPLEQ_ENTRY(idr_node) in_list;
48 };
49 SIMPLEQ_HEAD(idr_head, idr_node);
50
51 static struct {
52 kmutex_t lock;
53 struct idr_head preloaded_nodes;
54 struct idr_head discarded_nodes;
55 } idr_cache __cacheline_aligned;
56
57 int
58 linux_idr_module_init(void)
59 {
60
61 mutex_init(&idr_cache.lock, MUTEX_DEFAULT, IPL_VM);
62 SIMPLEQ_INIT(&idr_cache.preloaded_nodes);
63 SIMPLEQ_INIT(&idr_cache.discarded_nodes);
64 return 0;
65 }
66
67 void
68 linux_idr_module_fini(void)
69 {
70
71 KASSERT(SIMPLEQ_EMPTY(&idr_cache.discarded_nodes));
72 KASSERT(SIMPLEQ_EMPTY(&idr_cache.preloaded_nodes));
73 mutex_destroy(&idr_cache.lock);
74 }
75
76 static signed int idr_tree_compare_nodes(void *, const void *, const void *);
77 static signed int idr_tree_compare_key(void *, const void *, const void *);
78
79 static const rb_tree_ops_t idr_rb_ops = {
80 .rbto_compare_nodes = &idr_tree_compare_nodes,
81 .rbto_compare_key = &idr_tree_compare_key,
82 .rbto_node_offset = offsetof(struct idr_node, in_rb_node),
83 .rbto_context = NULL,
84 };
85
86 static signed int
87 idr_tree_compare_nodes(void *ctx __unused, const void *na, const void *nb)
88 {
89 const int a = ((const struct idr_node *)na)->in_index;
90 const int b = ((const struct idr_node *)nb)->in_index;
91
92 if (a < b)
93 return -1;
94 else if (b < a)
95 return +1;
96 else
97 return 0;
98 }
99
100 static signed int
101 idr_tree_compare_key(void *ctx __unused, const void *n, const void *key)
102 {
103 const int a = ((const struct idr_node *)n)->in_index;
104 const int b = *(const int *)key;
105
106 if (a < b)
107 return -1;
108 else if (b < a)
109 return +1;
110 else
111 return 0;
112 }
113
114 void
115 idr_init(struct idr *idr)
116 {
117
118 mutex_init(&idr->idr_lock, MUTEX_DEFAULT, IPL_VM);
119 rb_tree_init(&idr->idr_tree, &idr_rb_ops);
120 }
121
122 void
123 idr_destroy(struct idr *idr)
124 {
125
126 #if 0 /* XXX No rb_tree_destroy? */
127 rb_tree_destroy(&idr->idr_tree);
128 #endif
129 mutex_destroy(&idr->idr_lock);
130 }
131
132 bool
133 idr_is_empty(struct idr *idr)
134 {
135
136 return (RB_TREE_MIN(&idr->idr_tree) == NULL);
137 }
138
139 void *
140 idr_find(struct idr *idr, int id)
141 {
142 const struct idr_node *node;
143 void *data;
144
145 mutex_spin_enter(&idr->idr_lock);
146 node = rb_tree_find_node(&idr->idr_tree, &id);
147 data = (node == NULL? NULL : node->in_data);
148 mutex_spin_exit(&idr->idr_lock);
149
150 return data;
151 }
152
153 void *
154 idr_get_next(struct idr *idr, int *idp)
155 {
156 const struct idr_node *node;
157 void *data;
158
159 mutex_spin_enter(&idr->idr_lock);
160 node = rb_tree_find_node_geq(&idr->idr_tree, idp);
161 if (node == NULL) {
162 data = NULL;
163 } else {
164 data = node->in_data;
165 *idp = node->in_index;
166 }
167 mutex_spin_exit(&idr->idr_lock);
168
169 return data;
170 }
171
172 void *
173 idr_replace(struct idr *idr, void *replacement, int id)
174 {
175 struct idr_node *node;
176 void *result;
177
178 mutex_spin_enter(&idr->idr_lock);
179 node = rb_tree_find_node(&idr->idr_tree, &id);
180 if (node == NULL) {
181 result = ERR_PTR(-ENOENT);
182 } else {
183 result = node->in_data;
184 node->in_data = replacement;
185 }
186 mutex_spin_exit(&idr->idr_lock);
187
188 return result;
189 }
190
191 void
192 idr_remove(struct idr *idr, int id)
193 {
194 struct idr_node *node;
195
196 mutex_spin_enter(&idr->idr_lock);
197 node = rb_tree_find_node(&idr->idr_tree, &id);
198 KASSERTMSG((node != NULL), "idr %p has no entry for id %d", idr, id);
199 rb_tree_remove_node(&idr->idr_tree, node);
200 mutex_spin_exit(&idr->idr_lock);
201 kfree(node);
202 }
203
204 void
205 idr_preload(gfp_t gfp)
206 {
207 struct idr_node *node;
208
209 if (ISSET(gfp, __GFP_WAIT))
210 ASSERT_SLEEPABLE();
211
212 node = kmalloc(sizeof(*node), gfp);
213 KASSERT(node != NULL || !ISSET(gfp, __GFP_WAIT));
214 if (node == NULL)
215 return;
216
217 mutex_spin_enter(&idr_cache.lock);
218 SIMPLEQ_INSERT_TAIL(&idr_cache.preloaded_nodes, node, in_list);
219 mutex_spin_exit(&idr_cache.lock);
220 }
221
222 int
223 idr_alloc(struct idr *idr, void *data, int start, int end, gfp_t gfp)
224 {
225 int maximum = (end <= 0? INT_MAX : (end - 1));
226 struct idr_node *node, *search, *collision __diagused;
227 int id = start;
228
229 /* Sanity-check inputs. */
230 if (ISSET(gfp, __GFP_WAIT))
231 ASSERT_SLEEPABLE();
232 if (__predict_false(start < 0))
233 return -EINVAL;
234 if (__predict_false(maximum < start))
235 return -ENOSPC;
236
237 /* Grab a node allocated by idr_preload. */
238 mutex_spin_enter(&idr_cache.lock);
239 if (SIMPLEQ_EMPTY(&idr_cache.preloaded_nodes)) {
240 mutex_spin_exit(&idr_cache.lock);
241 return -ENOMEM;
242 }
243 node = SIMPLEQ_FIRST(&idr_cache.preloaded_nodes);
244 SIMPLEQ_REMOVE_HEAD(&idr_cache.preloaded_nodes, in_list);
245 mutex_spin_exit(&idr_cache.lock);
246
247 /* Find an id. */
248 mutex_spin_enter(&idr->idr_lock);
249 search = rb_tree_find_node_geq(&idr->idr_tree, &start);
250 while ((search != NULL) && (search->in_index == id)) {
251 if (maximum <= id) {
252 id = -ENOSPC;
253 goto out;
254 }
255 search = rb_tree_iterate(&idr->idr_tree, search, RB_DIR_RIGHT);
256 id++;
257 }
258 node->in_index = id;
259 node->in_data = data;
260 collision = rb_tree_insert_node(&idr->idr_tree, node);
261 KASSERT(collision == node);
262 out: mutex_spin_exit(&idr->idr_lock);
263
264 if (id < 0) {
265 /* Discard the node on failure. */
266 mutex_spin_enter(&idr_cache.lock);
267 SIMPLEQ_INSERT_HEAD(&idr_cache.discarded_nodes, node, in_list);
268 mutex_spin_exit(&idr_cache.lock);
269 }
270 return id;
271 }
272
273 void
274 idr_preload_end(void)
275 {
276 struct idr_head temp = SIMPLEQ_HEAD_INITIALIZER(temp);
277 struct idr_node *node, *next;
278
279 mutex_spin_enter(&idr_cache.lock);
280 SIMPLEQ_FOREACH_SAFE(node, &idr_cache.discarded_nodes, in_list, next) {
281 SIMPLEQ_REMOVE_HEAD(&idr_cache.discarded_nodes, in_list);
282 SIMPLEQ_INSERT_HEAD(&temp, node, in_list);
283 }
284 mutex_spin_exit(&idr_cache.lock);
285
286 SIMPLEQ_FOREACH_SAFE(node, &temp, in_list, next) {
287 SIMPLEQ_REMOVE_HEAD(&temp, in_list);
288 kfree(node);
289 }
290 }
291
292 int
293 idr_for_each(struct idr *idr, int (*proc)(int, void *, void *), void *arg)
294 {
295 struct idr_node *node;
296 int error = 0;
297
298 /* XXX Caller must exclude modifications. */
299 membar_consumer();
300 RB_TREE_FOREACH(node, &idr->idr_tree) {
301 error = (*proc)(node->in_index, node->in_data, arg);
302 if (error)
303 break;
304 }
305
306 return error;
307 }
308