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 /* 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 */ 59 static TAILQ_HEAD(, pthread) free_threadq; 60 static umtx_t free_thread_lock; 61 static umtx_t tcb_lock; 62 static int free_thread_count = 0; 63 static int inited = 0; 64 65 LIST_HEAD(thread_hash_head, pthread); 66 #define HASH_QUEUES 128 67 static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 68 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES) 69 70 static void thr_destroy(struct pthread *curthread, struct pthread *thread); 71 72 void 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 90 void 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 } 135 136 struct 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 } 175 176 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 } else { 197 /* 198 * Add the thread to the free thread list, this also avoids 199 * pthread id is reused too quickly, may help some buggy apps. 200 */ 201 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 202 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 203 free_thread_count++; 204 THR_LOCK_RELEASE(curthread, &free_thread_lock); 205 } 206 } 207 208 static void 209 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 210 { 211 free(thread); 212 } 213 214 /* 215 * Add the thread to the list of all threads and increment 216 * number of active threads. 217 */ 218 void 219 _thr_link(struct pthread *curthread, struct pthread *thread) 220 { 221 THREAD_LIST_LOCK(curthread); 222 THR_LIST_ADD(thread); 223 _thread_active_threads++; 224 THREAD_LIST_UNLOCK(curthread); 225 } 226 227 /* 228 * Remove an active thread. 229 */ 230 void 231 _thr_unlink(struct pthread *curthread, struct pthread *thread) 232 { 233 THREAD_LIST_LOCK(curthread); 234 THR_LIST_REMOVE(thread); 235 _thread_active_threads--; 236 THREAD_LIST_UNLOCK(curthread); 237 } 238 239 void 240 _thr_hash_add(struct pthread *thread) 241 { 242 struct thread_hash_head *head; 243 244 head = &thr_hashtable[THREAD_HASH(thread)]; 245 LIST_INSERT_HEAD(head, thread, hle); 246 } 247 248 void 249 _thr_hash_remove(struct pthread *thread) 250 { 251 LIST_REMOVE(thread, hle); 252 } 253 254 struct pthread * 255 _thr_hash_find(struct pthread *thread) 256 { 257 struct pthread *td; 258 struct thread_hash_head *head; 259 260 head = &thr_hashtable[THREAD_HASH(thread)]; 261 LIST_FOREACH(td, head, hle) { 262 if (td == thread) 263 return (thread); 264 } 265 return (NULL); 266 } 267 268 /* 269 * Find a thread in the linked list of active threads and add a reference 270 * to it. Threads with positive reference counts will not be deallocated 271 * until all references are released. 272 */ 273 int 274 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 275 int include_dead) 276 { 277 int ret; 278 279 if (thread == NULL) 280 /* Invalid thread: */ 281 return (EINVAL); 282 283 THREAD_LIST_LOCK(curthread); 284 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 285 thread->refcount++; 286 } 287 THREAD_LIST_UNLOCK(curthread); 288 289 /* Return zero if the thread exists: */ 290 return (ret); 291 } 292 293 void 294 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 295 { 296 THREAD_LIST_LOCK(curthread); 297 _thr_ref_delete_unlocked(curthread, thread); 298 THREAD_LIST_UNLOCK(curthread); 299 } 300 301 void 302 _thr_ref_delete_unlocked(struct pthread *curthread, struct pthread *thread) 303 { 304 if (thread != NULL) { 305 thread->refcount--; 306 if ((thread->refcount == 0) && thread->state == PS_DEAD && 307 (thread->tlflags & TLFLAGS_DETACHED) != 0) 308 THR_GCLIST_ADD(thread); 309 } 310 } 311 312 int 313 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 314 int include_dead) 315 { 316 struct pthread *pthread; 317 318 if (thread == NULL) 319 /* Invalid thread: */ 320 return (EINVAL); 321 322 pthread = _thr_hash_find(thread); 323 if (pthread) { 324 if (include_dead == 0 && pthread->state == PS_DEAD) { 325 pthread = NULL; 326 } 327 } 328 329 /* Return zero if the thread exists: */ 330 return ((pthread != NULL) ? 0 : ESRCH); 331 } 332