FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_kobj.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2000,2003 Doug Rabson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/kobj.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/mutex.h>
38 #include <sys/sysctl.h>
39 #ifndef TEST
40 #include <sys/systm.h>
41 #endif
42
43 #ifdef TEST
44 #include "usertest.h"
45 #endif
46
47 static MALLOC_DEFINE(M_KOBJ, "kobj", "Kernel object structures");
48
49 #ifdef KOBJ_STATS
50
51 u_int kobj_lookup_hits;
52 u_int kobj_lookup_misses;
53
54 SYSCTL_UINT(_kern, OID_AUTO, kobj_hits, CTLFLAG_RD,
55 &kobj_lookup_hits, 0, "");
56 SYSCTL_UINT(_kern, OID_AUTO, kobj_misses, CTLFLAG_RD,
57 &kobj_lookup_misses, 0, "");
58
59 #endif
60
61 static struct mtx kobj_mtx;
62 static int kobj_mutex_inited;
63 static int kobj_next_id = 1;
64
65 #define KOBJ_LOCK() mtx_lock(&kobj_mtx)
66 #define KOBJ_UNLOCK() mtx_unlock(&kobj_mtx)
67 #define KOBJ_ASSERT(what) mtx_assert(&kobj_mtx, what);
68
69 SYSCTL_INT(_kern, OID_AUTO, kobj_methodcount, CTLFLAG_RD,
70 &kobj_next_id, 0, "");
71
72 static void
73 kobj_init_mutex(void *arg)
74 {
75 if (!kobj_mutex_inited) {
76 mtx_init(&kobj_mtx, "kobj", NULL, MTX_DEF);
77 kobj_mutex_inited = 1;
78 }
79 }
80
81 SYSINIT(kobj, SI_SUB_LOCK, SI_ORDER_ANY, kobj_init_mutex, NULL);
82
83 /*
84 * This method structure is used to initialise new caches. Since the
85 * desc pointer is NULL, it is guaranteed never to match any read
86 * descriptors.
87 */
88 static const struct kobj_method null_method = {
89 0, 0,
90 };
91
92 int
93 kobj_error_method(void)
94 {
95
96 return ENXIO;
97 }
98
99 static void
100 kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops)
101 {
102 kobj_method_t *m;
103 int i;
104
105 /*
106 * Don't do anything if we are already compiled.
107 */
108 if (cls->ops)
109 return;
110
111 /*
112 * First register any methods which need it.
113 */
114 for (i = 0, m = cls->methods; m->desc; i++, m++) {
115 if (m->desc->id == 0)
116 m->desc->id = kobj_next_id++;
117 }
118
119 /*
120 * Then initialise the ops table.
121 */
122 for (i = 0; i < KOBJ_CACHE_SIZE; i++)
123 ops->cache[i] = &null_method;
124 ops->cls = cls;
125 cls->ops = ops;
126 }
127
128 static int
129 kobj_class_compile1(kobj_class_t cls, int mflags)
130 {
131 kobj_ops_t ops;
132
133 KOBJ_ASSERT(MA_NOTOWNED);
134
135 ops = malloc(sizeof(struct kobj_ops), M_KOBJ, mflags);
136 if (ops == NULL)
137 return (ENOMEM);
138
139 /*
140 * We may have lost a race for kobj_class_compile here - check
141 * to make sure someone else hasn't already compiled this
142 * class.
143 */
144 KOBJ_LOCK();
145 if (cls->ops) {
146 KOBJ_UNLOCK();
147 free(ops, M_KOBJ);
148 return (0);
149 }
150 kobj_class_compile_common(cls, ops);
151 KOBJ_UNLOCK();
152 return (0);
153 }
154
155 void
156 kobj_class_compile(kobj_class_t cls)
157 {
158 int error;
159
160 error = kobj_class_compile1(cls, M_WAITOK);
161 KASSERT(error == 0, ("kobj_class_compile1 returned %d", error));
162 }
163
164 void
165 kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops)
166 {
167
168 KASSERT(kobj_mutex_inited == 0,
169 ("%s: only supported during early cycles", __func__));
170
171 /*
172 * Increment refs to make sure that the ops table is not freed.
173 */
174 cls->refs++;
175 kobj_class_compile_common(cls, ops);
176 }
177
178 static kobj_method_t*
179 kobj_lookup_method_class(kobj_class_t cls, kobjop_desc_t desc)
180 {
181 kobj_method_t *methods = cls->methods;
182 kobj_method_t *ce;
183
184 for (ce = methods; ce && ce->desc; ce++) {
185 if (ce->desc == desc) {
186 return ce;
187 }
188 }
189
190 return NULL;
191 }
192
193 static kobj_method_t*
194 kobj_lookup_method_mi(kobj_class_t cls,
195 kobjop_desc_t desc)
196 {
197 kobj_method_t *ce;
198 kobj_class_t *basep;
199
200 ce = kobj_lookup_method_class(cls, desc);
201 if (ce)
202 return ce;
203
204 basep = cls->baseclasses;
205 if (basep) {
206 for (; *basep; basep++) {
207 ce = kobj_lookup_method_mi(*basep, desc);
208 if (ce)
209 return ce;
210 }
211 }
212
213 return NULL;
214 }
215
216 kobj_method_t*
217 kobj_lookup_method(kobj_class_t cls,
218 kobj_method_t **cep,
219 kobjop_desc_t desc)
220 {
221 kobj_method_t *ce;
222
223 ce = kobj_lookup_method_mi(cls, desc);
224 if (!ce)
225 ce = &desc->deflt;
226 if (cep)
227 *cep = ce;
228 return ce;
229 }
230
231 void
232 kobj_class_free(kobj_class_t cls)
233 {
234 void* ops = NULL;
235
236 KOBJ_ASSERT(MA_NOTOWNED);
237 KOBJ_LOCK();
238
239 /*
240 * Protect against a race between kobj_create and
241 * kobj_delete.
242 */
243 if (cls->refs == 0) {
244 /*
245 * For now we don't do anything to unregister any methods
246 * which are no longer used.
247 */
248
249 /*
250 * Free memory and clean up.
251 */
252 ops = cls->ops;
253 cls->ops = NULL;
254 }
255
256 KOBJ_UNLOCK();
257
258 if (ops)
259 free(ops, M_KOBJ);
260 }
261
262 static void
263 kobj_init_common(kobj_t obj, kobj_class_t cls)
264 {
265
266 obj->ops = cls->ops;
267 cls->refs++;
268 }
269
270 static int
271 kobj_init1(kobj_t obj, kobj_class_t cls, int mflags)
272 {
273 int error;
274
275 KOBJ_LOCK();
276 while (cls->ops == NULL) {
277 /*
278 * kobj_class_compile doesn't want the lock held
279 * because of the call to malloc - we drop the lock
280 * and re-try.
281 */
282 KOBJ_UNLOCK();
283 error = kobj_class_compile1(cls, mflags);
284 if (error != 0)
285 return (error);
286 KOBJ_LOCK();
287 }
288 kobj_init_common(obj, cls);
289 KOBJ_UNLOCK();
290 return (0);
291 }
292
293 kobj_t
294 kobj_create(kobj_class_t cls, struct malloc_type *mtype, int mflags)
295 {
296 kobj_t obj;
297
298 obj = malloc(cls->size, mtype, mflags | M_ZERO);
299 if (obj == NULL)
300 return (NULL);
301 if (kobj_init1(obj, cls, mflags) != 0) {
302 free(obj, mtype);
303 return (NULL);
304 }
305 return (obj);
306 }
307
308 void
309 kobj_init(kobj_t obj, kobj_class_t cls)
310 {
311 int error;
312
313 error = kobj_init1(obj, cls, M_NOWAIT);
314 if (error != 0)
315 panic("kobj_init1 failed: error %d", error);
316 }
317
318 void
319 kobj_init_static(kobj_t obj, kobj_class_t cls)
320 {
321
322 KASSERT(kobj_mutex_inited == 0,
323 ("%s: only supported during early cycles", __func__));
324
325 kobj_init_common(obj, cls);
326 }
327
328 void
329 kobj_delete(kobj_t obj, struct malloc_type *mtype)
330 {
331 kobj_class_t cls = obj->ops->cls;
332 int refs;
333
334 /*
335 * Consider freeing the compiled method table for the class
336 * after its last instance is deleted. As an optimisation, we
337 * should defer this for a short while to avoid thrashing.
338 */
339 KOBJ_ASSERT(MA_NOTOWNED);
340 KOBJ_LOCK();
341 cls->refs--;
342 refs = cls->refs;
343 KOBJ_UNLOCK();
344
345 if (!refs)
346 kobj_class_free(cls);
347
348 obj->ops = NULL;
349 if (mtype)
350 free(obj, mtype);
351 }
Cache object: 5a4c089f2484785d890136f733ba558b
|