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 44 static MALLOC_DEFINE(M_KOBJ, "kobj", "Kernel object structures"); 45 46 #ifdef KOBJ_STATS 47 48 u_int kobj_lookup_hits; 49 u_int kobj_lookup_misses; 50 51 SYSCTL_UINT(_kern, OID_AUTO, kobj_hits, CTLFLAG_RD, 52 &kobj_lookup_hits, 0, ""); 53 SYSCTL_UINT(_kern, OID_AUTO, kobj_misses, CTLFLAG_RD, 54 &kobj_lookup_misses, 0, ""); 55 56 #endif 57 58 static struct mtx kobj_mtx; 59 static int kobj_mutex_inited; 60 static 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 66 SYSCTL_INT(_kern, OID_AUTO, kobj_methodcount, CTLFLAG_RD, 67 &kobj_next_id, 0, 68 "Number of kernel object methods registered"); 69 70 static void 71 kobj_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 79 SYSINIT(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 */ 86 static const struct kobj_method null_method = { 87 0, 0, 88 }; 89 90 int 91 kobj_error_method(void) 92 { 93 94 return ENXIO; 95 } 96 97 static void 98 kobj_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 } 125 126 static int 127 kobj_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 } 152 153 void 154 kobj_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 } 161 162 void 163 kobj_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 } 175 176 static kobj_method_t* 177 kobj_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 } 190 191 static kobj_method_t* 192 kobj_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 } 213 214 kobj_method_t* 215 kobj_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 } 228 229 void 230 kobj_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 } 259 260 static void 261 kobj_init_common(kobj_t obj, kobj_class_t cls) 262 { 263 264 obj->ops = cls->ops; 265 cls->refs++; 266 } 267 268 static int 269 kobj_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 } 290 291 kobj_t 292 kobj_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 } 305 306 void 307 kobj_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 } 315 316 void 317 kobj_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 } 325 326 void 327 kobj_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