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 "Number of kernel object methods registered"); 72 73 static void 74 kobj_init_mutex(void *arg) 75 { 76 if (!kobj_mutex_inited) { 77 mtx_init(&kobj_mtx, "kobj", NULL, MTX_DEF); 78 kobj_mutex_inited = 1; 79 } 80 } 81 82 SYSINIT(kobj, SI_SUB_LOCK, SI_ORDER_ANY, kobj_init_mutex, NULL); 83 84 /* 85 * This method structure is used to initialise new caches. Since the 86 * desc pointer is NULL, it is guaranteed never to match any read 87 * descriptors. 88 */ 89 static const struct kobj_method null_method = { 90 0, 0, 91 }; 92 93 int 94 kobj_error_method(void) 95 { 96 97 return ENXIO; 98 } 99 100 static void 101 kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops) 102 { 103 kobj_method_t *m; 104 int i; 105 106 /* 107 * Don't do anything if we are already compiled. 108 */ 109 if (cls->ops) 110 return; 111 112 /* 113 * First register any methods which need it. 114 */ 115 for (m = cls->methods; m->desc; m++) { 116 if (m->desc->id == 0) 117 m->desc->id = kobj_next_id++; 118 } 119 120 /* 121 * Then initialise the ops table. 122 */ 123 for (i = 0; i < KOBJ_CACHE_SIZE; i++) 124 ops->cache[i] = &null_method; 125 ops->cls = cls; 126 cls->ops = ops; 127 } 128 129 static int 130 kobj_class_compile1(kobj_class_t cls, int mflags) 131 { 132 kobj_ops_t ops; 133 134 KOBJ_ASSERT(MA_NOTOWNED); 135 136 ops = malloc(sizeof(struct kobj_ops), M_KOBJ, mflags); 137 if (ops == NULL) 138 return (ENOMEM); 139 140 /* 141 * We may have lost a race for kobj_class_compile here - check 142 * to make sure someone else hasn't already compiled this 143 * class. 144 */ 145 KOBJ_LOCK(); 146 if (cls->ops) { 147 KOBJ_UNLOCK(); 148 free(ops, M_KOBJ); 149 return (0); 150 } 151 kobj_class_compile_common(cls, ops); 152 KOBJ_UNLOCK(); 153 return (0); 154 } 155 156 void 157 kobj_class_compile(kobj_class_t cls) 158 { 159 int error __diagused; 160 161 error = kobj_class_compile1(cls, M_WAITOK); 162 KASSERT(error == 0, ("kobj_class_compile1 returned %d", error)); 163 } 164 165 void 166 kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops) 167 { 168 169 KASSERT(kobj_mutex_inited == 0, 170 ("%s: only supported during early cycles", __func__)); 171 172 /* 173 * Increment refs to make sure that the ops table is not freed. 174 */ 175 cls->refs++; 176 kobj_class_compile_common(cls, ops); 177 } 178 179 static kobj_method_t* 180 kobj_lookup_method_class(kobj_class_t cls, kobjop_desc_t desc) 181 { 182 kobj_method_t *methods = cls->methods; 183 kobj_method_t *ce; 184 185 for (ce = methods; ce && ce->desc; ce++) { 186 if (ce->desc == desc) { 187 return ce; 188 } 189 } 190 191 return NULL; 192 } 193 194 static kobj_method_t* 195 kobj_lookup_method_mi(kobj_class_t cls, 196 kobjop_desc_t desc) 197 { 198 kobj_method_t *ce; 199 kobj_class_t *basep; 200 201 ce = kobj_lookup_method_class(cls, desc); 202 if (ce) 203 return ce; 204 205 basep = cls->baseclasses; 206 if (basep) { 207 for (; *basep; basep++) { 208 ce = kobj_lookup_method_mi(*basep, desc); 209 if (ce) 210 return ce; 211 } 212 } 213 214 return NULL; 215 } 216 217 kobj_method_t* 218 kobj_lookup_method(kobj_class_t cls, 219 kobj_method_t **cep, 220 kobjop_desc_t desc) 221 { 222 kobj_method_t *ce; 223 224 ce = kobj_lookup_method_mi(cls, desc); 225 if (!ce) 226 ce = &desc->deflt; 227 if (cep) 228 *cep = ce; 229 return ce; 230 } 231 232 void 233 kobj_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 } 262 263 static void 264 kobj_init_common(kobj_t obj, kobj_class_t cls) 265 { 266 267 obj->ops = cls->ops; 268 cls->refs++; 269 } 270 271 static int 272 kobj_init1(kobj_t obj, kobj_class_t cls, int mflags) 273 { 274 int error; 275 276 KOBJ_LOCK(); 277 while (cls->ops == NULL) { 278 /* 279 * kobj_class_compile doesn't want the lock held 280 * because of the call to malloc - we drop the lock 281 * and re-try. 282 */ 283 KOBJ_UNLOCK(); 284 error = kobj_class_compile1(cls, mflags); 285 if (error != 0) 286 return (error); 287 KOBJ_LOCK(); 288 } 289 kobj_init_common(obj, cls); 290 KOBJ_UNLOCK(); 291 return (0); 292 } 293 294 kobj_t 295 kobj_create(kobj_class_t cls, struct malloc_type *mtype, int mflags) 296 { 297 kobj_t obj; 298 299 obj = malloc(cls->size, mtype, mflags | M_ZERO); 300 if (obj == NULL) 301 return (NULL); 302 if (kobj_init1(obj, cls, mflags) != 0) { 303 free(obj, mtype); 304 return (NULL); 305 } 306 return (obj); 307 } 308 309 void 310 kobj_init(kobj_t obj, kobj_class_t cls) 311 { 312 int error; 313 314 error = kobj_init1(obj, cls, M_NOWAIT); 315 if (error != 0) 316 panic("kobj_init1 failed: error %d", error); 317 } 318 319 void 320 kobj_init_static(kobj_t obj, kobj_class_t cls) 321 { 322 323 KASSERT(kobj_mutex_inited == 0, 324 ("%s: only supported during early cycles", __func__)); 325 326 kobj_init_common(obj, cls); 327 } 328 329 void 330 kobj_delete(kobj_t obj, struct malloc_type *mtype) 331 { 332 kobj_class_t cls = obj->ops->cls; 333 int refs; 334 335 /* 336 * Consider freeing the compiled method table for the class 337 * after its last instance is deleted. As an optimisation, we 338 * should defer this for a short while to avoid thrashing. 339 */ 340 KOBJ_ASSERT(MA_NOTOWNED); 341 KOBJ_LOCK(); 342 cls->refs--; 343 refs = cls->refs; 344 KOBJ_UNLOCK(); 345 346 if (!refs) 347 kobj_class_free(cls); 348 349 obj->ops = NULL; 350 if (mtype) 351 free(obj, mtype); 352 } 353