lib/libthr/thread/thr_list.c

   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
  28 #include <sys/cdefs.h>
  29 __FBSDID("$FreeBSD$");
  30
  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 "libc_private.h"
  39 #include "thr_private.h"
  40 #include "static_tls.h"
  41
  42 /*#define DEBUG_THREAD_LIST */
  43 #ifdef DEBUG_THREAD_LIST
  44 #define DBG_MSG         stdout_debug
  45 #else
  46 #define DBG_MSG(x...)
  47 #endif
  48
  49 #define MAX_THREADS             100000
  50
  51 /*
  52  * Define a high water mark for the maximum number of threads that
  53  * will be cached.  Once this level is reached, any extra threads
  54  * will be free()'d.
  55  */
  56 #define MAX_CACHED_THREADS      100
  57
  58 /*
  59  * We've got to keep track of everything that is allocated, not only
  60  * to have a speedy free list, but also so they can be deallocated
  61  * after a fork().
  62  */
  63 static TAILQ_HEAD(, pthread)    free_threadq;
  64 static struct umutex            free_thread_lock = DEFAULT_UMUTEX;
  65 static struct umutex            tcb_lock = DEFAULT_UMUTEX;
  66 static int                      free_thread_count = 0;
  67 static int                      inited = 0;
  68 static int                      total_threads;
  69
  70 LIST_HEAD(thread_hash_head, pthread);
  71 #define HASH_QUEUES     128
  72 static struct thread_hash_head  thr_hashtable[HASH_QUEUES];
  73 #define THREAD_HASH(thrd)       (((unsigned long)thrd >> 8) % HASH_QUEUES)
  74
  75 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
  76
  77 void
  78 _thr_list_init(void)
  79 {
  80         int i;
  81
  82         _gc_count = 0;
  83         total_threads = 1;
  84         _thr_urwlock_init(&_thr_list_lock);
  85         TAILQ_INIT(&_thread_list);
  86         TAILQ_INIT(&free_threadq);
  87         _thr_umutex_init(&free_thread_lock);
  88         _thr_umutex_init(&tcb_lock);
  89         if (inited) {
  90                 for (i = 0; i < HASH_QUEUES; ++i)
  91                         LIST_INIT(&thr_hashtable[i]);
  92         }
  93         inited = 1;
  94 }
  95
  96 void
  97 _thr_gc(struct pthread *curthread)
  98 {
  99         struct pthread *td, *td_next;
 100         TAILQ_HEAD(, pthread) worklist;
 101
 102         TAILQ_INIT(&worklist);
 103         THREAD_LIST_WRLOCK(curthread);
 104
 105         /* Check the threads waiting for GC. */
 106         TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
 107                 if (td->tid != TID_TERMINATED) {
 108                         /* make sure we are not still in userland */
 109                         continue;
 110                 }
 111                 _thr_stack_free(&td->attr);
 112                 THR_GCLIST_REMOVE(td);
 113                 TAILQ_INSERT_HEAD(&worklist, td, gcle);
 114         }
 115         THREAD_LIST_UNLOCK(curthread);
 116
 117         while ((td = TAILQ_FIRST(&worklist)) != NULL) {
 118                 TAILQ_REMOVE(&worklist, td, gcle);
 119                 /*
 120                  * XXX we don't free initial thread, because there might
 121                  * have some code referencing initial thread.
 122                  */
 123                 if (td == _thr_initial) {
 124                         DBG_MSG("Initial thread won't be freed\n");
 125                         continue;
 126                 }
 127
 128                 _thr_free(curthread, td);
 129         }
 130 }
 131
 132 struct pthread *
 133 _thr_alloc(struct pthread *curthread)
 134 {
 135         struct pthread  *thread = NULL;
 136         struct tcb      *tcb;
 137
 138         if (curthread != NULL) {
 139                 if (GC_NEEDED())
 140                         _thr_gc(curthread);
 141                 if (free_thread_count > 0) {
 142                         THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 143                         if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 144                                 TAILQ_REMOVE(&free_threadq, thread, tle);
 145                                 free_thread_count--;
 146                         }
 147                         THR_LOCK_RELEASE(curthread, &free_thread_lock);
 148                 }
 149         }
 150         if (thread == NULL) {
 151                 if (total_threads > MAX_THREADS)
 152                         return (NULL);
 153                 atomic_fetchadd_int(&total_threads, 1);
 154                 thread = calloc(1, sizeof(struct pthread));
 155                 if (thread == NULL) {
 156                         atomic_fetchadd_int(&total_threads, -1);
 157                         return (NULL);
 158                 }
 159                 if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
 160                     (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
 161                         thr_destroy(curthread, thread);
 162                         atomic_fetchadd_int(&total_threads, -1);
 163                         return (NULL);
 164                 }
 165         } else {
 166                 bzero(&thread->_pthread_startzero,
 167                         __rangeof(struct pthread, _pthread_startzero, _pthread_endzero));
 168         }
 169         if (curthread != NULL) {
 170                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 171                 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
 172                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 173         } else {
 174                 tcb = _tcb_ctor(thread, 1 /* initial tls */);
 175         }
 176         if (tcb != NULL) {
 177                 thread->tcb = tcb;
 178         } else {
 179                 thr_destroy(curthread, thread);
 180                 atomic_fetchadd_int(&total_threads, -1);
 181                 thread = NULL;
 182         }
 183         return (thread);
 184 }
 185
 186 void
 187 _thr_free(struct pthread *curthread, struct pthread *thread)
 188 {
 189         DBG_MSG("Freeing thread %p\n", thread);
 190
 191         /*
 192          * Always free tcb, as we only know it is part of RTLD TLS
 193          * block, but don't know its detail and can not assume how
 194          * it works, so better to avoid caching it here.
 195          */
 196         if (curthread != NULL) {
 197                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 198                 _tcb_dtor(thread->tcb);
 199                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 200         } else {
 201                 _tcb_dtor(thread->tcb);
 202         }
 203         thread->tcb = NULL;
 204         if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 205                 thr_destroy(curthread, thread);
 206                 atomic_fetchadd_int(&total_threads, -1);
 207         } else {
 208                 /*
 209                  * Add the thread to the free thread list, this also avoids
 210                  * pthread id is reused too quickly, may help some buggy apps.
 211                  */
 212                 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 213                 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 214                 free_thread_count++;
 215                 THR_LOCK_RELEASE(curthread, &free_thread_lock);
 216         }
 217 }
 218
 219 static void
 220 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 221 {
 222         if (thread->sleepqueue != NULL)
 223                 _sleepq_free(thread->sleepqueue);
 224         if (thread->wake_addr != NULL)
 225                 _thr_release_wake_addr(thread->wake_addr);
 226         free(thread);
 227 }
 228
 229 /*
 230  * Add the thread to the list of all threads and increment
 231  * number of active threads.
 232  */
 233 void
 234 _thr_link(struct pthread *curthread, struct pthread *thread)
 235 {
 236         THREAD_LIST_WRLOCK(curthread);
 237         THR_LIST_ADD(thread);
 238         THREAD_LIST_UNLOCK(curthread);
 239         atomic_add_int(&_thread_active_threads, 1);
 240 }
 241
 242 /*
 243  * Remove an active thread.
 244  */
 245 void
 246 _thr_unlink(struct pthread *curthread, struct pthread *thread)
 247 {
 248         THREAD_LIST_WRLOCK(curthread);
 249         THR_LIST_REMOVE(thread);
 250         THREAD_LIST_UNLOCK(curthread);
 251         atomic_add_int(&_thread_active_threads, -1);
 252 }
 253
 254 void
 255 _thr_hash_add(struct pthread *thread)
 256 {
 257         struct thread_hash_head *head;
 258
 259         head = &thr_hashtable[THREAD_HASH(thread)];
 260         LIST_INSERT_HEAD(head, thread, hle);
 261 }
 262
 263 void
 264 _thr_hash_remove(struct pthread *thread)
 265 {
 266         LIST_REMOVE(thread, hle);
 267 }
 268
 269 struct pthread *
 270 _thr_hash_find(struct pthread *thread)
 271 {
 272         struct pthread *td;
 273         struct thread_hash_head *head;
 274
 275         head = &thr_hashtable[THREAD_HASH(thread)];
 276         LIST_FOREACH(td, head, hle) {
 277                 if (td == thread)
 278                         return (thread);
 279         }
 280         return (NULL);
 281 }
 282
 283 /*
 284  * Find a thread in the linked list of active threads and add a reference
 285  * to it.  Threads with positive reference counts will not be deallocated
 286  * until all references are released.
 287  */
 288 int
 289 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
 290     int include_dead)
 291 {
 292         int ret;
 293
 294         if (thread == NULL)
 295                 /* Invalid thread: */
 296                 return (EINVAL);
 297
 298         if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
 299                 thread->refcount++;
 300                 THR_CRITICAL_ENTER(curthread);
 301                 THR_THREAD_UNLOCK(curthread, thread);
 302         }
 303
 304         /* Return zero if the thread exists: */
 305         return (ret);
 306 }
 307
 308 void
 309 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
 310 {
 311         THR_THREAD_LOCK(curthread, thread);
 312         thread->refcount--;
 313         _thr_try_gc(curthread, thread);
 314         THR_CRITICAL_LEAVE(curthread);
 315 }
 316
 317 /* entered with thread lock held, exit with thread lock released */
 318 void
 319 _thr_try_gc(struct pthread *curthread, struct pthread *thread)
 320 {
 321         if (THR_SHOULD_GC(thread)) {
 322                 THR_REF_ADD(curthread, thread);
 323                 THR_THREAD_UNLOCK(curthread, thread);
 324                 THREAD_LIST_WRLOCK(curthread);
 325                 THR_THREAD_LOCK(curthread, thread);
 326                 THR_REF_DEL(curthread, thread);
 327                 if (THR_SHOULD_GC(thread)) {
 328                         THR_LIST_REMOVE(thread);
 329                         THR_GCLIST_ADD(thread);
 330                 }
 331                 THR_THREAD_UNLOCK(curthread, thread);
 332                 THREAD_LIST_UNLOCK(curthread);
 333         } else {
 334                 THR_THREAD_UNLOCK(curthread, thread);
 335         }
 336 }
 337
 338 /* return with thread lock held if thread is found */
 339 int
 340 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
 341     int include_dead)
 342 {
 343         struct pthread *pthread;
 344         int ret;
 345
 346         if (thread == NULL)
 347                 return (EINVAL);
 348
 349         ret = 0;
 350         THREAD_LIST_RDLOCK(curthread);
 351         pthread = _thr_hash_find(thread);
 352         if (pthread) {
 353                 THR_THREAD_LOCK(curthread, pthread);
 354                 if (include_dead == 0 && pthread->state == PS_DEAD) {
 355                         THR_THREAD_UNLOCK(curthread, pthread);
 356                         ret = ESRCH;
 357                 }
 358         } else {
 359                 ret = ESRCH;
 360         }
 361         THREAD_LIST_UNLOCK(curthread);
 362         return (ret);
 363 }
 364
 365 #include "pthread_tls.h"
 366
 367 static void
 368 thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len,
 369     size_t total_len)
 370 {
 371
 372         memcpy((void *)tlsbase, src, len);
 373         memset((char *)tlsbase + len, 0, total_len - len);
 374 }
 375
 376 void
 377 __pthread_distribute_static_tls(size_t offset, void *src, size_t len,
 378     size_t total_len)
 379 {
 380         struct pthread *curthread, *thrd;
 381         uintptr_t tlsbase;
 382
 383         if (!_thr_is_inited()) {
 384                 tlsbase = _libc_get_static_tls_base(offset);
 385                 thr_distribute_static_tls(tlsbase, src, len, total_len);
 386                 return;
 387         }
 388         curthread = _get_curthread();
 389         THREAD_LIST_RDLOCK(curthread);
 390         TAILQ_FOREACH(thrd, &_thread_list, tle) {
 391                 tlsbase = _get_static_tls_base(thrd, offset);
 392                 thr_distribute_static_tls(tlsbase, src, len, total_len);
 393         }
 394         THREAD_LIST_UNLOCK(curthread);
 395 }