thr_list.c revision 154055
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: head/lib/libthr/thread/thr_list.c 154055 2006-01-05 13:51:22Z davidxu $ 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/* 48 * Define a high water mark for the maximum number of threads that 49 * will be cached. Once this level is reached, any extra threads 50 * will be free()'d. 51 */ 52#define MAX_CACHED_THREADS 100 53 54/* 55 * We've got to keep track of everything that is allocated, not only 56 * to have a speedy free list, but also so they can be deallocated 57 * after a fork(). 58 */ 59static TAILQ_HEAD(, pthread) free_threadq; 60static umtx_t free_thread_lock; 61static umtx_t tcb_lock; 62static int free_thread_count = 0; 63static int inited = 0; 64 65LIST_HEAD(thread_hash_head, pthread); 66#define HASH_QUEUES 128 67static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 68#define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES) 69 70static void thr_destroy(struct pthread *curthread, struct pthread *thread); 71 72void 73_thr_list_init(void) 74{ 75 int i; 76 77 _gc_count = 0; 78 _thr_umtx_init(&_thr_list_lock); 79 TAILQ_INIT(&_thread_list); 80 TAILQ_INIT(&free_threadq); 81 _thr_umtx_init(&free_thread_lock); 82 _thr_umtx_init(&tcb_lock); 83 if (inited) { 84 for (i = 0; i < HASH_QUEUES; ++i) 85 LIST_INIT(&thr_hashtable[i]); 86 } 87 inited = 1; 88} 89 90void 91_thr_gc(struct pthread *curthread) 92{ 93 struct pthread *td, *td_next; 94 TAILQ_HEAD(, pthread) worklist; 95 96 TAILQ_INIT(&worklist); 97 THREAD_LIST_LOCK(curthread); 98 99 /* Check the threads waiting for GC. */ 100 for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) { 101 td_next = TAILQ_NEXT(td, gcle); 102 if (td->tid != TID_TERMINATED) { 103 /* make sure we are not still in userland */ 104 continue; 105 } 106 _thr_stack_free(&td->attr); 107 if (((td->tlflags & TLFLAGS_DETACHED) != 0) && 108 (td->refcount == 0)) { 109 THR_GCLIST_REMOVE(td); 110 /* 111 * The thread has detached and is no longer 112 * referenced. It is safe to remove all 113 * remnants of the thread. 114 */ 115 THR_LIST_REMOVE(td); 116 TAILQ_INSERT_HEAD(&worklist, td, gcle); 117 } 118 } 119 THREAD_LIST_UNLOCK(curthread); 120 121 while ((td = TAILQ_FIRST(&worklist)) != NULL) { 122 TAILQ_REMOVE(&worklist, td, gcle); 123 /* 124 * XXX we don't free initial thread, because there might 125 * have some code referencing initial thread. 126 */ 127 if (td == _thr_initial) { 128 DBG_MSG("Initial thread won't be freed\n"); 129 continue; 130 } 131 132 _thr_free(curthread, td); 133 } 134} 135 136struct pthread * 137_thr_alloc(struct pthread *curthread) 138{ 139 struct pthread *thread = NULL; 140 struct tcb *tcb; 141 142 if (curthread != NULL) { 143 if (GC_NEEDED()) 144 _thr_gc(curthread); 145 if (free_thread_count > 0) { 146 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 147 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) { 148 TAILQ_REMOVE(&free_threadq, thread, tle); 149 free_thread_count--; 150 } 151 THR_LOCK_RELEASE(curthread, &free_thread_lock); 152 } 153 } 154 if (thread == NULL) { 155 thread = malloc(sizeof(struct pthread)); 156 if (thread == NULL) 157 return (NULL); 158 } 159 if (curthread != NULL) { 160 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 161 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 162 THR_LOCK_RELEASE(curthread, &tcb_lock); 163 } else { 164 tcb = _tcb_ctor(thread, 1 /* initial tls */); 165 } 166 if (tcb != NULL) { 167 memset(thread, 0, sizeof(*thread)); 168 thread->tcb = tcb; 169 } else { 170 thr_destroy(curthread, thread); 171 thread = NULL; 172 } 173 return (thread); 174} 175 176void 177_thr_free(struct pthread *curthread, struct pthread *thread) 178{ 179 DBG_MSG("Freeing thread %p\n", thread); 180 if (thread->name) { 181 free(thread->name); 182 thread->name = NULL; 183 } 184 /* 185 * Always free tcb, as we only know it is part of RTLD TLS 186 * block, but don't know its detail and can not assume how 187 * it works, so better to avoid caching it here. 188 */ 189 if (curthread != NULL) { 190 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 191 _tcb_dtor(thread->tcb); 192 THR_LOCK_RELEASE(curthread, &tcb_lock); 193 } else { 194 _tcb_dtor(thread->tcb); 195 } 196 thread->tcb = NULL; 197 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 198 thr_destroy(curthread, thread); 199 } else { 200 /* 201 * Add the thread to the free thread list, this also avoids 202 * pthread id is reused too quickly, may help some buggy apps. 203 */ 204 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 205 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 206 free_thread_count++; 207 THR_LOCK_RELEASE(curthread, &free_thread_lock); 208 } 209} 210 211static void 212thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 213{ 214 free(thread); 215} 216 217/* 218 * Add the thread to the list of all threads and increment 219 * number of active threads. 220 */ 221void 222_thr_link(struct pthread *curthread, struct pthread *thread) 223{ 224 THREAD_LIST_LOCK(curthread); 225 THR_LIST_ADD(thread); 226 _thread_active_threads++; 227 THREAD_LIST_UNLOCK(curthread); 228} 229 230/* 231 * Remove an active thread. 232 */ 233void 234_thr_unlink(struct pthread *curthread, struct pthread *thread) 235{ 236 THREAD_LIST_LOCK(curthread); 237 THR_LIST_REMOVE(thread); 238 _thread_active_threads--; 239 THREAD_LIST_UNLOCK(curthread); 240} 241 242void 243_thr_hash_add(struct pthread *thread) 244{ 245 struct thread_hash_head *head; 246 247 head = &thr_hashtable[THREAD_HASH(thread)]; 248 LIST_INSERT_HEAD(head, thread, hle); 249} 250 251void 252_thr_hash_remove(struct pthread *thread) 253{ 254 LIST_REMOVE(thread, hle); 255} 256 257struct pthread * 258_thr_hash_find(struct pthread *thread) 259{ 260 struct pthread *td; 261 struct thread_hash_head *head; 262 263 head = &thr_hashtable[THREAD_HASH(thread)]; 264 LIST_FOREACH(td, head, hle) { 265 if (td == thread) 266 return (thread); 267 } 268 return (NULL); 269} 270 271/* 272 * Find a thread in the linked list of active threads and add a reference 273 * to it. Threads with positive reference counts will not be deallocated 274 * until all references are released. 275 */ 276int 277_thr_ref_add(struct pthread *curthread, struct pthread *thread, 278 int include_dead) 279{ 280 int ret; 281 282 if (thread == NULL) 283 /* Invalid thread: */ 284 return (EINVAL); 285 286 THREAD_LIST_LOCK(curthread); 287 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 288 thread->refcount++; 289 } 290 THREAD_LIST_UNLOCK(curthread); 291 292 /* Return zero if the thread exists: */ 293 return (ret); 294} 295 296void 297_thr_ref_delete(struct pthread *curthread, struct pthread *thread) 298{ 299 THREAD_LIST_LOCK(curthread); 300 _thr_ref_delete_unlocked(curthread, thread); 301 THREAD_LIST_UNLOCK(curthread); 302} 303 304void 305_thr_ref_delete_unlocked(struct pthread *curthread, struct pthread *thread) 306{ 307 if (thread != NULL) { 308 thread->refcount--; 309 if ((thread->refcount == 0) && thread->state == PS_DEAD && 310 (thread->tlflags & TLFLAGS_DETACHED) != 0) 311 THR_GCLIST_ADD(thread); 312 } 313} 314 315int 316_thr_find_thread(struct pthread *curthread, struct pthread *thread, 317 int include_dead) 318{ 319 struct pthread *pthread; 320 321 if (thread == NULL) 322 /* Invalid thread: */ 323 return (EINVAL); 324 325 pthread = _thr_hash_find(thread); 326 if (pthread) { 327 if (include_dead == 0 && pthread->state == PS_DEAD) { 328 pthread = NULL; 329 } 330 } 331 332 /* Return zero if the thread exists: */ 333 return ((pthread != NULL) ? 0 : ESRCH); 334} 335