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