1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #include <sys/types.h> 32 #include <sys/queue.h> 33 34 #include <stdlib.h> 35 #include <string.h> 36 #include <pthread.h> 37 38 #include "libc_private.h" 39 #include "thr_private.h" 40 #include "static_tls.h" 41 42 /*#define DEBUG_THREAD_LIST */ 43 #ifdef DEBUG_THREAD_LIST 44 #define DBG_MSG stdout_debug 45 #else 46 #define DBG_MSG(x...) 47 #endif 48 49 #define MAX_THREADS 100000 50 51 /* 52 * Define a high water mark for the maximum number of threads that 53 * will be cached. Once this level is reached, any extra threads 54 * will be free()'d. 55 */ 56 #define MAX_CACHED_THREADS 100 57 58 /* 59 * We've got to keep track of everything that is allocated, not only 60 * to have a speedy free list, but also so they can be deallocated 61 * after a fork(). 62 */ 63 static TAILQ_HEAD(, pthread) free_threadq; 64 static struct umutex free_thread_lock = DEFAULT_UMUTEX; 65 static struct umutex tcb_lock = DEFAULT_UMUTEX; 66 static int free_thread_count = 0; 67 static int inited = 0; 68 static int total_threads; 69 70 LIST_HEAD(thread_hash_head, pthread); 71 #define HASH_QUEUES 128 72 static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 73 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES) 74 75 static void thr_destroy(struct pthread *curthread, struct pthread *thread); 76 77 void 78 _thr_list_init(void) 79 { 80 int i; 81 82 _gc_count = 0; 83 total_threads = 1; 84 _thr_urwlock_init(&_thr_list_lock); 85 TAILQ_INIT(&_thread_list); 86 TAILQ_INIT(&free_threadq); 87 _thr_umutex_init(&free_thread_lock); 88 _thr_umutex_init(&tcb_lock); 89 if (inited) { 90 for (i = 0; i < HASH_QUEUES; ++i) 91 LIST_INIT(&thr_hashtable[i]); 92 } 93 inited = 1; 94 } 95 96 void 97 _thr_gc(struct pthread *curthread) 98 { 99 struct pthread *td, *td_next; 100 TAILQ_HEAD(, pthread) worklist; 101 102 TAILQ_INIT(&worklist); 103 THREAD_LIST_WRLOCK(curthread); 104 105 /* Check the threads waiting for GC. */ 106 TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) { 107 if (td->tid != TID_TERMINATED) { 108 /* make sure we are not still in userland */ 109 continue; 110 } 111 _thr_stack_free(&td->attr); 112 THR_GCLIST_REMOVE(td); 113 TAILQ_INSERT_HEAD(&worklist, td, gcle); 114 } 115 THREAD_LIST_UNLOCK(curthread); 116 117 while ((td = TAILQ_FIRST(&worklist)) != NULL) { 118 TAILQ_REMOVE(&worklist, td, gcle); 119 /* 120 * XXX we don't free initial thread, because there might 121 * have some code referencing initial thread. 122 */ 123 if (td == _thr_initial) { 124 DBG_MSG("Initial thread won't be freed\n"); 125 continue; 126 } 127 128 _thr_free(curthread, td); 129 } 130 } 131 132 struct pthread * 133 _thr_alloc(struct pthread *curthread) 134 { 135 struct pthread *thread = NULL; 136 struct tcb *tcb; 137 138 if (curthread != NULL) { 139 if (GC_NEEDED()) 140 _thr_gc(curthread); 141 if (free_thread_count > 0) { 142 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 143 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) { 144 TAILQ_REMOVE(&free_threadq, thread, tle); 145 free_thread_count--; 146 } 147 THR_LOCK_RELEASE(curthread, &free_thread_lock); 148 } 149 } 150 if (thread == NULL) { 151 if (total_threads > MAX_THREADS) 152 return (NULL); 153 atomic_fetchadd_int(&total_threads, 1); 154 thread = calloc(1, sizeof(struct pthread)); 155 if (thread == NULL) { 156 atomic_fetchadd_int(&total_threads, -1); 157 return (NULL); 158 } 159 if ((thread->sleepqueue = _sleepq_alloc()) == NULL || 160 (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) { 161 thr_destroy(curthread, thread); 162 atomic_fetchadd_int(&total_threads, -1); 163 return (NULL); 164 } 165 } else { 166 bzero(&thread->_pthread_startzero, 167 __rangeof(struct pthread, _pthread_startzero, _pthread_endzero)); 168 } 169 if (curthread != NULL) { 170 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 171 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 172 THR_LOCK_RELEASE(curthread, &tcb_lock); 173 } else { 174 tcb = _tcb_ctor(thread, 1 /* initial tls */); 175 } 176 if (tcb != NULL) { 177 thread->tcb = tcb; 178 } else { 179 thr_destroy(curthread, thread); 180 atomic_fetchadd_int(&total_threads, -1); 181 thread = NULL; 182 } 183 return (thread); 184 } 185 186 void 187 _thr_free(struct pthread *curthread, struct pthread *thread) 188 { 189 DBG_MSG("Freeing thread %p\n", thread); 190 191 /* 192 * Always free tcb, as we only know it is part of RTLD TLS 193 * block, but don't know its detail and can not assume how 194 * it works, so better to avoid caching it here. 195 */ 196 if (curthread != NULL) { 197 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 198 _tcb_dtor(thread->tcb); 199 THR_LOCK_RELEASE(curthread, &tcb_lock); 200 } else { 201 _tcb_dtor(thread->tcb); 202 } 203 thread->tcb = NULL; 204 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 205 thr_destroy(curthread, thread); 206 atomic_fetchadd_int(&total_threads, -1); 207 } else { 208 /* 209 * Add the thread to the free thread list, this also avoids 210 * pthread id is reused too quickly, may help some buggy apps. 211 */ 212 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 213 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 214 free_thread_count++; 215 THR_LOCK_RELEASE(curthread, &free_thread_lock); 216 } 217 } 218 219 static void 220 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 221 { 222 if (thread->sleepqueue != NULL) 223 _sleepq_free(thread->sleepqueue); 224 if (thread->wake_addr != NULL) 225 _thr_release_wake_addr(thread->wake_addr); 226 free(thread); 227 } 228 229 /* 230 * Add the thread to the list of all threads and increment 231 * number of active threads. 232 */ 233 void 234 _thr_link(struct pthread *curthread, struct pthread *thread) 235 { 236 THREAD_LIST_WRLOCK(curthread); 237 THR_LIST_ADD(thread); 238 THREAD_LIST_UNLOCK(curthread); 239 atomic_add_int(&_thread_active_threads, 1); 240 } 241 242 /* 243 * Remove an active thread. 244 */ 245 void 246 _thr_unlink(struct pthread *curthread, struct pthread *thread) 247 { 248 THREAD_LIST_WRLOCK(curthread); 249 THR_LIST_REMOVE(thread); 250 THREAD_LIST_UNLOCK(curthread); 251 atomic_add_int(&_thread_active_threads, -1); 252 } 253 254 void 255 _thr_hash_add(struct pthread *thread) 256 { 257 struct thread_hash_head *head; 258 259 head = &thr_hashtable[THREAD_HASH(thread)]; 260 LIST_INSERT_HEAD(head, thread, hle); 261 } 262 263 void 264 _thr_hash_remove(struct pthread *thread) 265 { 266 LIST_REMOVE(thread, hle); 267 } 268 269 struct pthread * 270 _thr_hash_find(struct pthread *thread) 271 { 272 struct pthread *td; 273 struct thread_hash_head *head; 274 275 head = &thr_hashtable[THREAD_HASH(thread)]; 276 LIST_FOREACH(td, head, hle) { 277 if (td == thread) 278 return (thread); 279 } 280 return (NULL); 281 } 282 283 /* 284 * Find a thread in the linked list of active threads and add a reference 285 * to it. Threads with positive reference counts will not be deallocated 286 * until all references are released. 287 */ 288 int 289 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 290 int include_dead) 291 { 292 int ret; 293 294 if (thread == NULL) 295 /* Invalid thread: */ 296 return (EINVAL); 297 298 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 299 thread->refcount++; 300 THR_CRITICAL_ENTER(curthread); 301 THR_THREAD_UNLOCK(curthread, thread); 302 } 303 304 /* Return zero if the thread exists: */ 305 return (ret); 306 } 307 308 void 309 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 310 { 311 THR_THREAD_LOCK(curthread, thread); 312 thread->refcount--; 313 _thr_try_gc(curthread, thread); 314 THR_CRITICAL_LEAVE(curthread); 315 } 316 317 /* entered with thread lock held, exit with thread lock released */ 318 void 319 _thr_try_gc(struct pthread *curthread, struct pthread *thread) 320 { 321 if (THR_SHOULD_GC(thread)) { 322 THR_REF_ADD(curthread, thread); 323 THR_THREAD_UNLOCK(curthread, thread); 324 THREAD_LIST_WRLOCK(curthread); 325 THR_THREAD_LOCK(curthread, thread); 326 THR_REF_DEL(curthread, thread); 327 if (THR_SHOULD_GC(thread)) { 328 THR_LIST_REMOVE(thread); 329 THR_GCLIST_ADD(thread); 330 } 331 THR_THREAD_UNLOCK(curthread, thread); 332 THREAD_LIST_UNLOCK(curthread); 333 } else { 334 THR_THREAD_UNLOCK(curthread, thread); 335 } 336 } 337 338 /* return with thread lock held if thread is found */ 339 int 340 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 341 int include_dead) 342 { 343 struct pthread *pthread; 344 int ret; 345 346 if (thread == NULL) 347 return (EINVAL); 348 349 ret = 0; 350 THREAD_LIST_RDLOCK(curthread); 351 pthread = _thr_hash_find(thread); 352 if (pthread) { 353 THR_THREAD_LOCK(curthread, pthread); 354 if (include_dead == 0 && pthread->state == PS_DEAD) { 355 THR_THREAD_UNLOCK(curthread, pthread); 356 ret = ESRCH; 357 } 358 } else { 359 ret = ESRCH; 360 } 361 THREAD_LIST_UNLOCK(curthread); 362 return (ret); 363 } 364 365 #include "pthread_tls.h" 366 367 static void 368 thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len, 369 size_t total_len) 370 { 371 372 memcpy((void *)tlsbase, src, len); 373 memset((char *)tlsbase + len, 0, total_len - len); 374 } 375 376 void 377 __pthread_distribute_static_tls(size_t offset, void *src, size_t len, 378 size_t total_len) 379 { 380 struct pthread *curthread, *thrd; 381 uintptr_t tlsbase; 382 383 if (!_thr_is_inited()) { 384 tlsbase = _libc_get_static_tls_base(offset); 385 thr_distribute_static_tls(tlsbase, src, len, total_len); 386 return; 387 } 388 curthread = _get_curthread(); 389 THREAD_LIST_RDLOCK(curthread); 390 TAILQ_FOREACH(thrd, &_thread_list, tle) { 391 tlsbase = _get_static_tls_base(thrd, offset); 392 thr_distribute_static_tls(tlsbase, src, len, total_len); 393 } 394 THREAD_LIST_UNLOCK(curthread); 395 } 396