1/*-
2 * Copyright (c) 2000,2003 Doug Rabson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
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
45static MALLOC_DEFINE(M_KOBJ, "kobj", "Kernel object structures");
46
47#ifdef KOBJ_STATS
48
49u_int kobj_lookup_hits;
50u_int kobj_lookup_misses;
51
52SYSCTL_UINT(_kern, OID_AUTO, kobj_hits, CTLFLAG_RD,
53	   &kobj_lookup_hits, 0, "");
54SYSCTL_UINT(_kern, OID_AUTO, kobj_misses, CTLFLAG_RD,
55	   &kobj_lookup_misses, 0, "");
56
57#endif
58
59static struct mtx kobj_mtx;
60static int kobj_mutex_inited;
61static 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
67SYSCTL_INT(_kern, OID_AUTO, kobj_methodcount, CTLFLAG_RD,
68	   &kobj_next_id, 0, "");
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 (i = 0, m = cls->methods; m->desc; i++, 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
126void
127kobj_class_compile(kobj_class_t cls)
128{
129	kobj_ops_t ops;
130
131	KOBJ_ASSERT(MA_NOTOWNED);
132
133	/*
134	 * Allocate space for the compiled ops table.
135	 */
136	ops = malloc(sizeof(struct kobj_ops), M_KOBJ, M_NOWAIT);
137	if (!ops)
138		panic("%s: out of memory", __func__);
139
140	KOBJ_LOCK();
141
142	/*
143	 * We may have lost a race for kobj_class_compile here - check
144	 * to make sure someone else hasn't already compiled this
145	 * class.
146	 */
147	if (cls->ops) {
148		KOBJ_UNLOCK();
149		free(ops, M_KOBJ);
150		return;
151	}
152
153	kobj_class_compile_common(cls, ops);
154	KOBJ_UNLOCK();
155}
156
157void
158kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops)
159{
160
161	KASSERT(kobj_mutex_inited == 0,
162	    ("%s: only supported during early cycles", __func__));
163
164	/*
165	 * Increment refs to make sure that the ops table is not freed.
166	 */
167	cls->refs++;
168	kobj_class_compile_common(cls, ops);
169}
170
171static kobj_method_t*
172kobj_lookup_method_class(kobj_class_t cls, kobjop_desc_t desc)
173{
174	kobj_method_t *methods = cls->methods;
175	kobj_method_t *ce;
176
177	for (ce = methods; ce && ce->desc; ce++) {
178		if (ce->desc == desc) {
179			return ce;
180		}
181	}
182
183	return NULL;
184}
185
186static kobj_method_t*
187kobj_lookup_method_mi(kobj_class_t cls,
188		      kobjop_desc_t desc)
189{
190	kobj_method_t *ce;
191	kobj_class_t *basep;
192
193	ce = kobj_lookup_method_class(cls, desc);
194	if (ce)
195		return ce;
196
197	basep = cls->baseclasses;
198	if (basep) {
199		for (; *basep; basep++) {
200			ce = kobj_lookup_method_mi(*basep, desc);
201			if (ce)
202				return ce;
203		}
204	}
205
206	return NULL;
207}
208
209kobj_method_t*
210kobj_lookup_method(kobj_class_t cls,
211		   kobj_method_t **cep,
212		   kobjop_desc_t desc)
213{
214	kobj_method_t *ce;
215
216#ifdef KOBJ_STATS
217	/*
218	 * Correct for the 'hit' assumption in KOBJOPLOOKUP and record
219	 * a 'miss'.
220	 */
221	kobj_lookup_hits--;
222	kobj_lookup_misses++;
223#endif
224
225	ce = kobj_lookup_method_mi(cls, desc);
226	if (!ce)
227		ce = &desc->deflt;
228	*cep = ce;
229	return ce;
230}
231
232void
233kobj_class_free(kobj_class_t cls)
234{
235	void* ops = NULL;
236
237	KOBJ_ASSERT(MA_NOTOWNED);
238	KOBJ_LOCK();
239
240	/*
241	 * Protect against a race between kobj_create and
242	 * kobj_delete.
243	 */
244	if (cls->refs == 0) {
245		/*
246		 * For now we don't do anything to unregister any methods
247		 * which are no longer used.
248		 */
249
250		/*
251		 * Free memory and clean up.
252		 */
253		ops = cls->ops;
254		cls->ops = NULL;
255	}
256
257	KOBJ_UNLOCK();
258
259	if (ops)
260		free(ops, M_KOBJ);
261}
262
263kobj_t
264kobj_create(kobj_class_t cls,
265	    struct malloc_type *mtype,
266	    int mflags)
267{
268	kobj_t obj;
269
270	/*
271	 * Allocate and initialise the new object.
272	 */
273	obj = malloc(cls->size, mtype, mflags | M_ZERO);
274	if (!obj)
275		return NULL;
276	kobj_init(obj, cls);
277
278	return obj;
279}
280
281static void
282kobj_init_common(kobj_t obj, kobj_class_t cls)
283{
284
285	obj->ops = cls->ops;
286	cls->refs++;
287}
288
289void
290kobj_init(kobj_t obj, kobj_class_t cls)
291{
292	KOBJ_ASSERT(MA_NOTOWNED);
293  retry:
294	KOBJ_LOCK();
295
296	/*
297	 * Consider compiling the class' method table.
298	 */
299	if (!cls->ops) {
300		/*
301		 * kobj_class_compile doesn't want the lock held
302		 * because of the call to malloc - we drop the lock
303		 * and re-try.
304		 */
305		KOBJ_UNLOCK();
306		kobj_class_compile(cls);
307		goto retry;
308	}
309
310	kobj_init_common(obj, cls);
311
312	KOBJ_UNLOCK();
313}
314
315void
316kobj_init_static(kobj_t obj, kobj_class_t cls)
317{
318
319	KASSERT(kobj_mutex_inited == 0,
320	    ("%s: only supported during early cycles", __func__));
321
322	kobj_init_common(obj, cls);
323}
324
325void
326kobj_delete(kobj_t obj, struct malloc_type *mtype)
327{
328	kobj_class_t cls = obj->ops->cls;
329	int refs;
330
331	/*
332	 * Consider freeing the compiled method table for the class
333	 * after its last instance is deleted. As an optimisation, we
334	 * should defer this for a short while to avoid thrashing.
335	 */
336	KOBJ_ASSERT(MA_NOTOWNED);
337	KOBJ_LOCK();
338	cls->refs--;
339	refs = cls->refs;
340	KOBJ_UNLOCK();
341
342	if (!refs)
343		kobj_class_free(cls);
344
345	obj->ops = NULL;
346	if (mtype)
347		free(obj, mtype);
348}
349