1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/kobj.h>
33 #include <sys/lock.h>
34 #include <sys/malloc.h>
35 #include <sys/mutex.h>
36 #include <sys/sysctl.h>
37 #ifndef TEST
38 #include <sys/systm.h>
39 #endif
40
41 #ifdef TEST
42 #include "usertest.h"
43 #endif
44
45 static MALLOC_DEFINE(M_KOBJ, "kobj", "Kernel object structures");
46
47 #ifdef KOBJ_STATS
48
49 u_int kobj_lookup_hits;
50 u_int kobj_lookup_misses;
51
52 SYSCTL_UINT(_kern, OID_AUTO, kobj_hits, CTLFLAG_RD,
53 &kobj_lookup_hits, 0, "");
54 SYSCTL_UINT(_kern, OID_AUTO, kobj_misses, CTLFLAG_RD,
55 &kobj_lookup_misses, 0, "");
56
57 #endif
58
59 static struct mtx kobj_mtx;
60 static int kobj_mutex_inited;
61 static int kobj_next_id = 1;
62
63 #define KOBJ_LOCK() mtx_lock(&kobj_mtx)
64 #define KOBJ_UNLOCK() mtx_unlock(&kobj_mtx)
65 #define KOBJ_ASSERT(what) mtx_assert(&kobj_mtx, what);
66
67 SYSCTL_INT(_kern, OID_AUTO, kobj_methodcount, CTLFLAG_RD,
68 &kobj_next_id, 0,
69 "Number of kernel object methods registered");
70
71 static void
kobj_init_mutex(void * arg)72 kobj_init_mutex(void *arg)
73 {
74 if (!kobj_mutex_inited) {
75 mtx_init(&kobj_mtx, "kobj", NULL, MTX_DEF);
76 kobj_mutex_inited = 1;
77 }
78 }
79
80 SYSINIT(kobj, SI_SUB_LOCK, SI_ORDER_ANY, kobj_init_mutex, NULL);
81
82 /*
83 * This method structure is used to initialise new caches. Since the
84 * desc pointer is NULL, it is guaranteed never to match any read
85 * descriptors.
86 */
87 static const struct kobj_method null_method = {
88 0, 0,
89 };
90
91 int
kobj_error_method(void)92 kobj_error_method(void)
93 {
94
95 return ENXIO;
96 }
97
98 static void
kobj_class_compile_common(kobj_class_t cls,kobj_ops_t ops)99 kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops)
100 {
101 kobj_method_t *m;
102 int i;
103
104 /*
105 * Don't do anything if we are already compiled.
106 */
107 if (cls->ops)
108 return;
109
110 /*
111 * First register any methods which need it.
112 */
113 for (i = 0, m = cls->methods; m->desc; i++, m++) {
114 if (m->desc->id == 0)
115 m->desc->id = kobj_next_id++;
116 }
117
118 /*
119 * Then initialise the ops table.
120 */
121 for (i = 0; i < KOBJ_CACHE_SIZE; i++)
122 ops->cache[i] = &null_method;
123 ops->cls = cls;
124 cls->ops = ops;
125 }
126
127 static int
kobj_class_compile1(kobj_class_t cls,int mflags)128 kobj_class_compile1(kobj_class_t cls, int mflags)
129 {
130 kobj_ops_t ops;
131
132 KOBJ_ASSERT(MA_NOTOWNED);
133
134 ops = malloc(sizeof(struct kobj_ops), M_KOBJ, mflags);
135 if (ops == NULL)
136 return (ENOMEM);
137
138 /*
139 * We may have lost a race for kobj_class_compile here - check
140 * to make sure someone else hasn't already compiled this
141 * class.
142 */
143 KOBJ_LOCK();
144 if (cls->ops) {
145 KOBJ_UNLOCK();
146 free(ops, M_KOBJ);
147 return (0);
148 }
149 kobj_class_compile_common(cls, ops);
150 KOBJ_UNLOCK();
151 return (0);
152 }
153
154 void
kobj_class_compile(kobj_class_t cls)155 kobj_class_compile(kobj_class_t cls)
156 {
157 int error;
158
159 error = kobj_class_compile1(cls, M_WAITOK);
160 KASSERT(error == 0, ("kobj_class_compile1 returned %d", error));
161 }
162
163 void
kobj_class_compile_static(kobj_class_t cls,kobj_ops_t ops)164 kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops)
165 {
166
167 KASSERT(kobj_mutex_inited == 0,
168 ("%s: only supported during early cycles", __func__));
169
170 /*
171 * Increment refs to make sure that the ops table is not freed.
172 */
173 cls->refs++;
174 kobj_class_compile_common(cls, ops);
175 }
176
177 static kobj_method_t*
kobj_lookup_method_class(kobj_class_t cls,kobjop_desc_t desc)178 kobj_lookup_method_class(kobj_class_t cls, kobjop_desc_t desc)
179 {
180 kobj_method_t *methods = cls->methods;
181 kobj_method_t *ce;
182
183 for (ce = methods; ce && ce->desc; ce++) {
184 if (ce->desc == desc) {
185 return ce;
186 }
187 }
188
189 return NULL;
190 }
191
192 static kobj_method_t*
kobj_lookup_method_mi(kobj_class_t cls,kobjop_desc_t desc)193 kobj_lookup_method_mi(kobj_class_t cls,
194 kobjop_desc_t desc)
195 {
196 kobj_method_t *ce;
197 kobj_class_t *basep;
198
199 ce = kobj_lookup_method_class(cls, desc);
200 if (ce)
201 return ce;
202
203 basep = cls->baseclasses;
204 if (basep) {
205 for (; *basep; basep++) {
206 ce = kobj_lookup_method_mi(*basep, desc);
207 if (ce)
208 return ce;
209 }
210 }
211
212 return NULL;
213 }
214
215 kobj_method_t*
kobj_lookup_method(kobj_class_t cls,kobj_method_t ** cep,kobjop_desc_t desc)216 kobj_lookup_method(kobj_class_t cls,
217 kobj_method_t **cep,
218 kobjop_desc_t desc)
219 {
220 kobj_method_t *ce;
221
222 ce = kobj_lookup_method_mi(cls, desc);
223 if (!ce)
224 ce = &desc->deflt;
225 if (cep)
226 *cep = ce;
227 return ce;
228 }
229
230 void
kobj_class_free(kobj_class_t cls)231 kobj_class_free(kobj_class_t cls)
232 {
233 void* ops = NULL;
234
235 KOBJ_ASSERT(MA_NOTOWNED);
236 KOBJ_LOCK();
237
238 /*
239 * Protect against a race between kobj_create and
240 * kobj_delete.
241 */
242 if (cls->refs == 0) {
243 /*
244 * For now we don't do anything to unregister any methods
245 * which are no longer used.
246 */
247
248 /*
249 * Free memory and clean up.
250 */
251 ops = cls->ops;
252 cls->ops = NULL;
253 }
254
255 KOBJ_UNLOCK();
256
257 if (ops)
258 free(ops, M_KOBJ);
259 }
260
261 static void
kobj_init_common(kobj_t obj,kobj_class_t cls)262 kobj_init_common(kobj_t obj, kobj_class_t cls)
263 {
264
265 obj->ops = cls->ops;
266 cls->refs++;
267 }
268
269 static int
kobj_init1(kobj_t obj,kobj_class_t cls,int mflags)270 kobj_init1(kobj_t obj, kobj_class_t cls, int mflags)
271 {
272 int error;
273
274 KOBJ_LOCK();
275 while (cls->ops == NULL) {
276 /*
277 * kobj_class_compile doesn't want the lock held
278 * because of the call to malloc - we drop the lock
279 * and re-try.
280 */
281 KOBJ_UNLOCK();
282 error = kobj_class_compile1(cls, mflags);
283 if (error != 0)
284 return (error);
285 KOBJ_LOCK();
286 }
287 kobj_init_common(obj, cls);
288 KOBJ_UNLOCK();
289 return (0);
290 }
291
292 kobj_t
kobj_create(kobj_class_t cls,struct malloc_type * mtype,int mflags)293 kobj_create(kobj_class_t cls, struct malloc_type *mtype, int mflags)
294 {
295 kobj_t obj;
296
297 obj = malloc(cls->size, mtype, mflags | M_ZERO);
298 if (obj == NULL)
299 return (NULL);
300 if (kobj_init1(obj, cls, mflags) != 0) {
301 free(obj, mtype);
302 return (NULL);
303 }
304 return (obj);
305 }
306
307 void
kobj_init(kobj_t obj,kobj_class_t cls)308 kobj_init(kobj_t obj, kobj_class_t cls)
309 {
310 int error;
311
312 error = kobj_init1(obj, cls, M_NOWAIT);
313 if (error != 0)
314 panic("kobj_init1 failed: error %d", error);
315 }
316
317 void
kobj_init_static(kobj_t obj,kobj_class_t cls)318 kobj_init_static(kobj_t obj, kobj_class_t cls)
319 {
320
321 KASSERT(kobj_mutex_inited == 0,
322 ("%s: only supported during early cycles", __func__));
323
324 kobj_init_common(obj, cls);
325 }
326
327 void
kobj_delete(kobj_t obj,struct malloc_type * mtype)328 kobj_delete(kobj_t obj, struct malloc_type *mtype)
329 {
330 kobj_class_t cls = obj->ops->cls;
331 int refs;
332
333 /*
334 * Consider freeing the compiled method table for the class
335 * after its last instance is deleted. As an optimisation, we
336 * should defer this for a short while to avoid thrashing.
337 */
338 KOBJ_ASSERT(MA_NOTOWNED);
339 KOBJ_LOCK();
340 cls->refs--;
341 refs = cls->refs;
342 KOBJ_UNLOCK();
343
344 if (!refs)
345 kobj_class_free(cls);
346
347 obj->ops = NULL;
348 if (mtype)
349 free(obj, mtype);
350 }
351