1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 5 * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice unmodified, this list of conditions, and the following 13 * disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/types.h> 34 #include <sys/queue.h> 35 36 #include <stdlib.h> 37 #include <string.h> 38 #include <pthread.h> 39 40 #include "libc_private.h" 41 #include "thr_private.h" 42 43 /*#define DEBUG_THREAD_LIST */ 44 #ifdef DEBUG_THREAD_LIST 45 #define DBG_MSG stdout_debug 46 #else 47 #define DBG_MSG(x...) 48 #endif 49 50 #define MAX_THREADS 100000 51 52 /* 53 * Define a high water mark for the maximum number of threads that 54 * will be cached. Once this level is reached, any extra threads 55 * will be free()'d. 56 */ 57 #define MAX_CACHED_THREADS 100 58 59 /* 60 * We've got to keep track of everything that is allocated, not only 61 * to have a speedy free list, but also so they can be deallocated 62 * after a fork(). 63 */ 64 static TAILQ_HEAD(, pthread) free_threadq; 65 static struct umutex free_thread_lock = DEFAULT_UMUTEX; 66 static struct umutex tcb_lock = DEFAULT_UMUTEX; 67 static int free_thread_count = 0; 68 static int inited = 0; 69 static int total_threads; 70 71 LIST_HEAD(thread_hash_head, pthread); 72 #define HASH_QUEUES 128 73 static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 74 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES) 75 76 static void thr_destroy(struct pthread *curthread, struct pthread *thread); 77 78 void 79 _thr_list_init(void) 80 { 81 int i; 82 83 _gc_count = 0; 84 total_threads = 1; 85 _thr_urwlock_init(&_thr_list_lock); 86 TAILQ_INIT(&_thread_list); 87 TAILQ_INIT(&free_threadq); 88 _thr_umutex_init(&free_thread_lock); 89 _thr_umutex_init(&tcb_lock); 90 if (inited) { 91 for (i = 0; i < HASH_QUEUES; ++i) 92 LIST_INIT(&thr_hashtable[i]); 93 } 94 inited = 1; 95 } 96 97 void 98 _thr_gc(struct pthread *curthread) 99 { 100 struct pthread *td, *td_next; 101 TAILQ_HEAD(, pthread) worklist; 102 103 TAILQ_INIT(&worklist); 104 THREAD_LIST_WRLOCK(curthread); 105 106 /* Check the threads waiting for GC. */ 107 TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) { 108 if (td->tid != TID_TERMINATED) { 109 /* make sure we are not still in userland */ 110 continue; 111 } 112 _thr_stack_free(&td->attr); 113 THR_GCLIST_REMOVE(td); 114 TAILQ_INSERT_HEAD(&worklist, td, gcle); 115 } 116 THREAD_LIST_UNLOCK(curthread); 117 118 while ((td = TAILQ_FIRST(&worklist)) != NULL) { 119 TAILQ_REMOVE(&worklist, td, gcle); 120 /* 121 * XXX we don't free initial thread, because there might 122 * have some code referencing initial thread. 123 */ 124 if (td == _thr_initial) { 125 DBG_MSG("Initial thread won't be freed\n"); 126 continue; 127 } 128 129 _thr_free(curthread, td); 130 } 131 } 132 133 struct pthread * 134 _thr_alloc(struct pthread *curthread) 135 { 136 struct pthread *thread = NULL; 137 struct tcb *tcb; 138 139 if (curthread != NULL) { 140 if (GC_NEEDED()) 141 _thr_gc(curthread); 142 if (free_thread_count > 0) { 143 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 144 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) { 145 TAILQ_REMOVE(&free_threadq, thread, tle); 146 free_thread_count--; 147 } 148 THR_LOCK_RELEASE(curthread, &free_thread_lock); 149 } 150 } 151 if (thread == NULL) { 152 if (total_threads > MAX_THREADS) 153 return (NULL); 154 atomic_fetchadd_int(&total_threads, 1); 155 thread = calloc(1, sizeof(struct pthread)); 156 if (thread == NULL) { 157 atomic_fetchadd_int(&total_threads, -1); 158 return (NULL); 159 } 160 if ((thread->sleepqueue = _sleepq_alloc()) == NULL || 161 (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) { 162 thr_destroy(curthread, thread); 163 atomic_fetchadd_int(&total_threads, -1); 164 return (NULL); 165 } 166 } else { 167 bzero(&thread->_pthread_startzero, 168 __rangeof(struct pthread, _pthread_startzero, _pthread_endzero)); 169 } 170 if (curthread != NULL) { 171 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 172 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 173 THR_LOCK_RELEASE(curthread, &tcb_lock); 174 } else { 175 tcb = _tcb_ctor(thread, 1 /* initial tls */); 176 } 177 if (tcb != NULL) { 178 thread->tcb = tcb; 179 } else { 180 thr_destroy(curthread, thread); 181 atomic_fetchadd_int(&total_threads, -1); 182 thread = NULL; 183 } 184 return (thread); 185 } 186 187 void 188 _thr_free(struct pthread *curthread, struct pthread *thread) 189 { 190 DBG_MSG("Freeing thread %p\n", thread); 191 192 /* 193 * Always free tcb, as we only know it is part of RTLD TLS 194 * block, but don't know its detail and can not assume how 195 * it works, so better to avoid caching it here. 196 */ 197 if (curthread != NULL) { 198 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 199 _tcb_dtor(thread->tcb); 200 THR_LOCK_RELEASE(curthread, &tcb_lock); 201 } else { 202 _tcb_dtor(thread->tcb); 203 } 204 thread->tcb = NULL; 205 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 206 thr_destroy(curthread, thread); 207 atomic_fetchadd_int(&total_threads, -1); 208 } else { 209 /* 210 * Add the thread to the free thread list, this also avoids 211 * pthread id is reused too quickly, may help some buggy apps. 212 */ 213 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 214 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 215 free_thread_count++; 216 THR_LOCK_RELEASE(curthread, &free_thread_lock); 217 } 218 } 219 220 static void 221 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 222 { 223 if (thread->sleepqueue != NULL) 224 _sleepq_free(thread->sleepqueue); 225 if (thread->wake_addr != NULL) 226 _thr_release_wake_addr(thread->wake_addr); 227 free(thread); 228 } 229 230 /* 231 * Add the thread to the list of all threads and increment 232 * number of active threads. 233 */ 234 void 235 _thr_link(struct pthread *curthread, struct pthread *thread) 236 { 237 THREAD_LIST_WRLOCK(curthread); 238 THR_LIST_ADD(thread); 239 THREAD_LIST_UNLOCK(curthread); 240 atomic_add_int(&_thread_active_threads, 1); 241 } 242 243 /* 244 * Remove an active thread. 245 */ 246 void 247 _thr_unlink(struct pthread *curthread, struct pthread *thread) 248 { 249 THREAD_LIST_WRLOCK(curthread); 250 THR_LIST_REMOVE(thread); 251 THREAD_LIST_UNLOCK(curthread); 252 atomic_add_int(&_thread_active_threads, -1); 253 } 254 255 void 256 _thr_hash_add(struct pthread *thread) 257 { 258 struct thread_hash_head *head; 259 260 head = &thr_hashtable[THREAD_HASH(thread)]; 261 LIST_INSERT_HEAD(head, thread, hle); 262 } 263 264 void 265 _thr_hash_remove(struct pthread *thread) 266 { 267 LIST_REMOVE(thread, hle); 268 } 269 270 struct pthread * 271 _thr_hash_find(struct pthread *thread) 272 { 273 struct pthread *td; 274 struct thread_hash_head *head; 275 276 head = &thr_hashtable[THREAD_HASH(thread)]; 277 LIST_FOREACH(td, head, hle) { 278 if (td == thread) 279 return (thread); 280 } 281 return (NULL); 282 } 283 284 /* 285 * Find a thread in the linked list of active threads and add a reference 286 * to it. Threads with positive reference counts will not be deallocated 287 * until all references are released. 288 */ 289 int 290 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 291 int include_dead) 292 { 293 int ret; 294 295 if (thread == NULL) 296 /* Invalid thread: */ 297 return (EINVAL); 298 299 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 300 thread->refcount++; 301 THR_CRITICAL_ENTER(curthread); 302 THR_THREAD_UNLOCK(curthread, thread); 303 } 304 305 /* Return zero if the thread exists: */ 306 return (ret); 307 } 308 309 void 310 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 311 { 312 THR_THREAD_LOCK(curthread, thread); 313 thread->refcount--; 314 _thr_try_gc(curthread, thread); 315 THR_CRITICAL_LEAVE(curthread); 316 } 317 318 /* entered with thread lock held, exit with thread lock released */ 319 void 320 _thr_try_gc(struct pthread *curthread, struct pthread *thread) 321 { 322 if (THR_SHOULD_GC(thread)) { 323 THR_REF_ADD(curthread, thread); 324 THR_THREAD_UNLOCK(curthread, thread); 325 THREAD_LIST_WRLOCK(curthread); 326 THR_THREAD_LOCK(curthread, thread); 327 THR_REF_DEL(curthread, thread); 328 if (THR_SHOULD_GC(thread)) { 329 THR_LIST_REMOVE(thread); 330 THR_GCLIST_ADD(thread); 331 } 332 THR_THREAD_UNLOCK(curthread, thread); 333 THREAD_LIST_UNLOCK(curthread); 334 } else { 335 THR_THREAD_UNLOCK(curthread, thread); 336 } 337 } 338 339 /* return with thread lock held if thread is found */ 340 int 341 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 342 int include_dead) 343 { 344 struct pthread *pthread; 345 int ret; 346 347 if (thread == NULL) 348 return (EINVAL); 349 350 ret = 0; 351 THREAD_LIST_RDLOCK(curthread); 352 pthread = _thr_hash_find(thread); 353 if (pthread) { 354 THR_THREAD_LOCK(curthread, pthread); 355 if (include_dead == 0 && pthread->state == PS_DEAD) { 356 THR_THREAD_UNLOCK(curthread, pthread); 357 ret = ESRCH; 358 } 359 } else { 360 ret = ESRCH; 361 } 362 THREAD_LIST_UNLOCK(curthread); 363 return (ret); 364 } 365