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