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 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 92 kobj_error_method(void) 93 { 94 95 return ENXIO; 96 } 97 98 static void 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 (m = cls->methods; m->desc; 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 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 155 kobj_class_compile(kobj_class_t cls) 156 { 157 int error __diagused; 158 159 error = kobj_class_compile1(cls, M_WAITOK); 160 KASSERT(error == 0, ("kobj_class_compile1 returned %d", error)); 161 } 162 163 void 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* 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* 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* 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 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 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 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 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 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 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 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