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 = malloc(sizeof(struct pthread)); 153 if (thread == NULL) { 154 atomic_fetchadd_int(&total_threads, -1); 155 return (NULL); 156 } 157 } 158 if (curthread != NULL) { 159 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 160 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 161 THR_LOCK_RELEASE(curthread, &tcb_lock); 162 } else { 163 tcb = _tcb_ctor(thread, 1 /* initial tls */); 164 } 165 if (tcb != NULL) { 166 memset(thread, 0, sizeof(*thread)); 167 thread->tcb = tcb; 168 thread->sleepqueue = _sleepq_alloc(); 169 thread->wake_addr = _thr_alloc_wake_addr(); 170 } else { 171 thr_destroy(curthread, thread); 172 atomic_fetchadd_int(&total_threads, -1); 173 thread = NULL; 174 } 175 return (thread); 176 } 177 178 void 179 _thr_free(struct pthread *curthread, struct pthread *thread) 180 { 181 DBG_MSG("Freeing thread %p\n", thread); 182 183 /* 184 * Always free tcb, as we only know it is part of RTLD TLS 185 * block, but don't know its detail and can not assume how 186 * it works, so better to avoid caching it here. 187 */ 188 if (curthread != NULL) { 189 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 190 _tcb_dtor(thread->tcb); 191 THR_LOCK_RELEASE(curthread, &tcb_lock); 192 } else { 193 _tcb_dtor(thread->tcb); 194 } 195 thread->tcb = NULL; 196 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 197 _sleepq_free(thread->sleepqueue); 198 _thr_release_wake_addr(thread->wake_addr); 199 thr_destroy(curthread, thread); 200 atomic_fetchadd_int(&total_threads, -1); 201 } else { 202 /* 203 * Add the thread to the free thread list, this also avoids 204 * pthread id is reused too quickly, may help some buggy apps. 205 */ 206 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 207 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 208 free_thread_count++; 209 THR_LOCK_RELEASE(curthread, &free_thread_lock); 210 } 211 } 212 213 static void 214 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 215 { 216 free(thread); 217 } 218 219 /* 220 * Add the thread to the list of all threads and increment 221 * number of active threads. 222 */ 223 void 224 _thr_link(struct pthread *curthread, struct pthread *thread) 225 { 226 THREAD_LIST_WRLOCK(curthread); 227 THR_LIST_ADD(thread); 228 THREAD_LIST_UNLOCK(curthread); 229 atomic_add_int(&_thread_active_threads, 1); 230 } 231 232 /* 233 * Remove an active thread. 234 */ 235 void 236 _thr_unlink(struct pthread *curthread, struct pthread *thread) 237 { 238 THREAD_LIST_WRLOCK(curthread); 239 THR_LIST_REMOVE(thread); 240 THREAD_LIST_UNLOCK(curthread); 241 atomic_add_int(&_thread_active_threads, -1); 242 } 243 244 void 245 _thr_hash_add(struct pthread *thread) 246 { 247 struct thread_hash_head *head; 248 249 head = &thr_hashtable[THREAD_HASH(thread)]; 250 LIST_INSERT_HEAD(head, thread, hle); 251 } 252 253 void 254 _thr_hash_remove(struct pthread *thread) 255 { 256 LIST_REMOVE(thread, hle); 257 } 258 259 struct pthread * 260 _thr_hash_find(struct pthread *thread) 261 { 262 struct pthread *td; 263 struct thread_hash_head *head; 264 265 head = &thr_hashtable[THREAD_HASH(thread)]; 266 LIST_FOREACH(td, head, hle) { 267 if (td == thread) 268 return (thread); 269 } 270 return (NULL); 271 } 272 273 /* 274 * Find a thread in the linked list of active threads and add a reference 275 * to it. Threads with positive reference counts will not be deallocated 276 * until all references are released. 277 */ 278 int 279 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 280 int include_dead) 281 { 282 int ret; 283 284 if (thread == NULL) 285 /* Invalid thread: */ 286 return (EINVAL); 287 288 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 289 thread->refcount++; 290 THR_CRITICAL_ENTER(curthread); 291 THR_THREAD_UNLOCK(curthread, thread); 292 } 293 294 /* Return zero if the thread exists: */ 295 return (ret); 296 } 297 298 void 299 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 300 { 301 THR_THREAD_LOCK(curthread, thread); 302 thread->refcount--; 303 _thr_try_gc(curthread, thread); 304 THR_CRITICAL_LEAVE(curthread); 305 } 306 307 /* entered with thread lock held, exit with thread lock released */ 308 void 309 _thr_try_gc(struct pthread *curthread, struct pthread *thread) 310 { 311 if (THR_SHOULD_GC(thread)) { 312 THR_REF_ADD(curthread, thread); 313 THR_THREAD_UNLOCK(curthread, thread); 314 THREAD_LIST_WRLOCK(curthread); 315 THR_THREAD_LOCK(curthread, thread); 316 THR_REF_DEL(curthread, thread); 317 if (THR_SHOULD_GC(thread)) { 318 THR_LIST_REMOVE(thread); 319 THR_GCLIST_ADD(thread); 320 } 321 THR_THREAD_UNLOCK(curthread, thread); 322 THREAD_LIST_UNLOCK(curthread); 323 } else { 324 THR_THREAD_UNLOCK(curthread, thread); 325 } 326 } 327 328 /* return with thread lock held if thread is found */ 329 int 330 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 331 int include_dead) 332 { 333 struct pthread *pthread; 334 int ret; 335 336 if (thread == NULL) 337 return (EINVAL); 338 339 ret = 0; 340 THREAD_LIST_RDLOCK(curthread); 341 pthread = _thr_hash_find(thread); 342 if (pthread) { 343 THR_THREAD_LOCK(curthread, pthread); 344 if (include_dead == 0 && pthread->state == PS_DEAD) { 345 THR_THREAD_UNLOCK(curthread, pthread); 346 ret = ESRCH; 347 } 348 } else { 349 ret = ESRCH; 350 } 351 THREAD_LIST_UNLOCK(curthread); 352 return (ret); 353 } 354