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 * $DragonFly: src/lib/libthread_xu/thread/thr_list.c,v 1.3 2005/03/29 19:26:20 joerg Exp $ 28 */ 29 30 #include <sys/cdefs.h> 31 #include <sys/types.h> 32 #include <sys/queue.h> 33 34 #include <stdlib.h> 35 #include <string.h> 36 #include <pthread.h> 37 38 #include "thr_private.h" 39 #include "libc_private.h" 40 41 /*#define DEBUG_THREAD_LIST */ 42 #ifdef DEBUG_THREAD_LIST 43 #define DBG_MSG stdout_debug 44 #else 45 #define DBG_MSG(x...) 46 #endif 47 48 /* 49 * Define a high water mark for the maximum number of threads that 50 * will be cached. Once this level is reached, any extra threads 51 * will be free()'d. 52 */ 53 #define MAX_CACHED_THREADS 100 54 55 /* 56 * We've got to keep track of everything that is allocated, not only 57 * to have a speedy free list, but also so they can be deallocated 58 * after a fork(). 59 */ 60 static TAILQ_HEAD(, pthread) free_threadq; 61 static umtx_t free_thread_lock; 62 static umtx_t tcb_lock; 63 static int free_thread_count = 0; 64 static int inited = 0; 65 static u_int64_t next_uniqueid = 1; 66 67 LIST_HEAD(thread_hash_head, pthread); 68 #define HASH_QUEUES 128 69 static struct thread_hash_head thr_hashtable[HASH_QUEUES]; 70 #define THREAD_HASH(thrd) (((unsigned long)thrd >> 12) % HASH_QUEUES) 71 72 static void thr_destroy(struct pthread *curthread, struct pthread *thread); 73 74 void 75 _thr_list_init(void) 76 { 77 int i; 78 79 _gc_count = 0; 80 _thr_umtx_init(&_thr_list_lock); 81 TAILQ_INIT(&_thread_list); 82 TAILQ_INIT(&free_threadq); 83 _thr_umtx_init(&free_thread_lock); 84 _thr_umtx_init(&tcb_lock); 85 if (inited) { 86 for (i = 0; i < HASH_QUEUES; ++i) 87 LIST_INIT(&thr_hashtable[i]); 88 } 89 inited = 1; 90 } 91 92 void 93 _thr_gc(struct pthread *curthread) 94 { 95 struct pthread *td, *td_next; 96 TAILQ_HEAD(, pthread) worklist; 97 98 TAILQ_INIT(&worklist); 99 THREAD_LIST_LOCK(curthread); 100 101 /* Check the threads waiting for GC. */ 102 for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) { 103 td_next = TAILQ_NEXT(td, gcle); 104 if (td->terminated == 0) { 105 /* make sure we are not still in userland */ 106 continue; 107 } 108 _thr_stack_free(&td->attr); 109 if (((td->tlflags & TLFLAGS_DETACHED) != 0) && 110 (td->refcount == 0)) { 111 THR_GCLIST_REMOVE(td); 112 /* 113 * The thread has detached and is no longer 114 * referenced. It is safe to remove all 115 * remnants of the thread. 116 */ 117 THR_LIST_REMOVE(td); 118 TAILQ_INSERT_HEAD(&worklist, td, gcle); 119 } 120 } 121 THREAD_LIST_UNLOCK(curthread); 122 123 while ((td = TAILQ_FIRST(&worklist)) != NULL) { 124 TAILQ_REMOVE(&worklist, td, gcle); 125 /* 126 * XXX we don't free initial thread, because there might 127 * have some code referencing initial thread. 128 */ 129 if (td == _thr_initial) { 130 DBG_MSG("Initial thread won't be freed\n"); 131 continue; 132 } 133 134 DBG_MSG("Freeing thread %p\n", td); 135 _thr_free(curthread, td); 136 } 137 } 138 139 struct pthread * 140 _thr_alloc(struct pthread *curthread) 141 { 142 struct pthread *thread = NULL; 143 struct tls_tcb *tcb; 144 145 if (curthread != NULL) { 146 if (GC_NEEDED()) 147 _thr_gc(curthread); 148 if (free_thread_count > 0) { 149 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 150 if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) { 151 TAILQ_REMOVE(&free_threadq, thread, tle); 152 free_thread_count--; 153 } 154 THR_LOCK_RELEASE(curthread, &free_thread_lock); 155 } 156 } 157 if (thread == NULL) { 158 thread = malloc(sizeof(struct pthread)); 159 if (thread == NULL) 160 return (NULL); 161 } 162 if (curthread != NULL) { 163 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 164 tcb = _tcb_ctor(thread, 0 /* not initial tls */); 165 THR_LOCK_RELEASE(curthread, &tcb_lock); 166 } else { 167 tcb = _tcb_ctor(thread, 1 /* initial tls */); 168 } 169 if (tcb != NULL) { 170 memset(thread, 0, sizeof(*thread)); 171 thread->tcb = tcb; 172 } else { 173 thr_destroy(curthread, thread); 174 thread = NULL; 175 } 176 return (thread); 177 } 178 179 void 180 _thr_free(struct pthread *curthread, struct pthread *thread) 181 { 182 DBG_MSG("Freeing thread %p\n", thread); 183 if (thread->name) { 184 free(thread->name); 185 thread->name = NULL; 186 } 187 /* 188 * Always free tcb, as we only know it is part of RTLD TLS 189 * block, but don't know its detail and can not assume how 190 * it works, so better to avoid caching it here. 191 */ 192 if (curthread != NULL) { 193 THR_LOCK_ACQUIRE(curthread, &tcb_lock); 194 _tcb_dtor(thread->tcb); 195 THR_LOCK_RELEASE(curthread, &tcb_lock); 196 } else { 197 _tcb_dtor(thread->tcb); 198 } 199 thread->tcb = NULL; 200 if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) { 201 thr_destroy(curthread, thread); 202 } else { 203 /* 204 * Add the thread to the free thread list, this also avoids 205 * pthread id is reused too quickly, may help some buggy apps. 206 */ 207 THR_LOCK_ACQUIRE(curthread, &free_thread_lock); 208 TAILQ_INSERT_TAIL(&free_threadq, thread, tle); 209 free_thread_count++; 210 THR_LOCK_RELEASE(curthread, &free_thread_lock); 211 } 212 } 213 214 static void 215 thr_destroy(struct pthread *curthread __unused, struct pthread *thread) 216 { 217 free(thread); 218 } 219 220 /* 221 * Add an active thread: 222 * 223 * o Assign the thread a unique id (which GDB uses to track 224 * threads. 225 * o Add the thread to the list of all threads and increment 226 * number of active threads. 227 */ 228 void 229 _thr_link(struct pthread *curthread, struct pthread *thread) 230 { 231 THREAD_LIST_LOCK(curthread); 232 /* 233 * Initialize the unique id (which GDB uses to track 234 * threads), add the thread to the list of all threads, 235 * and 236 */ 237 thread->uniqueid = next_uniqueid++; 238 THR_LIST_ADD(thread); 239 if (thread->attr.flags & PTHREAD_DETACHED) 240 thread->tlflags |= TLFLAGS_DETACHED; 241 _thread_active_threads++; 242 THREAD_LIST_UNLOCK(curthread); 243 } 244 245 /* 246 * Remove an active thread. 247 */ 248 void 249 _thr_unlink(struct pthread *curthread, struct pthread *thread) 250 { 251 THREAD_LIST_LOCK(curthread); 252 THR_LIST_REMOVE(thread); 253 _thread_active_threads--; 254 THREAD_LIST_UNLOCK(curthread); 255 } 256 257 void 258 _thr_hash_add(struct pthread *thread) 259 { 260 struct thread_hash_head *head; 261 262 head = &thr_hashtable[THREAD_HASH(thread)]; 263 LIST_INSERT_HEAD(head, thread, hle); 264 } 265 266 void 267 _thr_hash_remove(struct pthread *thread) 268 { 269 LIST_REMOVE(thread, hle); 270 } 271 272 struct pthread * 273 _thr_hash_find(struct pthread *thread) 274 { 275 struct pthread *td; 276 struct thread_hash_head *head; 277 278 head = &thr_hashtable[THREAD_HASH(thread)]; 279 LIST_FOREACH(td, head, hle) { 280 if (td == thread) 281 return (thread); 282 } 283 return (NULL); 284 } 285 286 /* 287 * Find a thread in the linked list of active threads and add a reference 288 * to it. Threads with positive reference counts will not be deallocated 289 * until all references are released. 290 */ 291 int 292 _thr_ref_add(struct pthread *curthread, struct pthread *thread, 293 int include_dead) 294 { 295 int ret; 296 297 if (thread == NULL) 298 /* Invalid thread: */ 299 return (EINVAL); 300 301 THREAD_LIST_LOCK(curthread); 302 if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) { 303 thread->refcount++; 304 } 305 THREAD_LIST_UNLOCK(curthread); 306 307 /* Return zero if the thread exists: */ 308 return (ret); 309 } 310 311 void 312 _thr_ref_delete(struct pthread *curthread, struct pthread *thread) 313 { 314 if (thread != NULL) { 315 THREAD_LIST_LOCK(curthread); 316 thread->refcount--; 317 if ((thread->refcount == 0) && 318 (thread->tlflags & TLFLAGS_GC_SAFE) != 0) 319 THR_GCLIST_ADD(thread); 320 THREAD_LIST_UNLOCK(curthread); 321 } 322 } 323 324 int 325 _thr_find_thread(struct pthread *curthread, struct pthread *thread, 326 int include_dead) 327 { 328 struct pthread *pthread; 329 330 if (thread == NULL) 331 /* Invalid thread: */ 332 return (EINVAL); 333 334 pthread = _thr_hash_find(thread); 335 if (pthread) { 336 if (include_dead == 0 && pthread->state == PS_DEAD) { 337 pthread = NULL; 338 } 339 } 340 341 /* Return zero if the thread exists: */ 342 return ((pthread != NULL) ? 0 : ESRCH); 343 } 344