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