lib/libthr/thread/thr_list.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
   5  * Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice unmodified, this list of conditions, and the following
  13  *    disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #include <sys/types.h>
  34 #include <sys/queue.h>
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <pthread.h>
  39
  40 #include "libc_private.h"
  41 #include "thr_private.h"
  42 #include "static_tls.h"
  43
  44 /*#define DEBUG_THREAD_LIST */
  45 #ifdef DEBUG_THREAD_LIST
  46 #define DBG_MSG         stdout_debug
  47 #else
  48 #define DBG_MSG(x...)
  49 #endif
  50
  51 #define MAX_THREADS             100000
  52
  53 /*
  54  * Define a high water mark for the maximum number of threads that
  55  * will be cached.  Once this level is reached, any extra threads
  56  * will be free()'d.
  57  */
  58 #define MAX_CACHED_THREADS      100
  59
  60 /*
  61  * We've got to keep track of everything that is allocated, not only
  62  * to have a speedy free list, but also so they can be deallocated
  63  * after a fork().
  64  */
  65 static TAILQ_HEAD(, pthread)    free_threadq;
  66 static struct umutex            free_thread_lock = DEFAULT_UMUTEX;
  67 static struct umutex            tcb_lock = DEFAULT_UMUTEX;
  68 static int                      free_thread_count = 0;
  69 static int                      inited = 0;
  70 static int                      total_threads;
  71
  72 LIST_HEAD(thread_hash_head, pthread);
  73 #define HASH_QUEUES     128
  74 static struct thread_hash_head  thr_hashtable[HASH_QUEUES];
  75 #define THREAD_HASH(thrd)       (((unsigned long)thrd >> 8) % HASH_QUEUES)
  76
  77 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
  78
  79 void
  80 _thr_list_init(void)
  81 {
  82         int i;
  83
  84         _gc_count = 0;
  85         total_threads = 1;
  86         _thr_urwlock_init(&_thr_list_lock);
  87         TAILQ_INIT(&_thread_list);
  88         TAILQ_INIT(&free_threadq);
  89         _thr_umutex_init(&free_thread_lock);
  90         _thr_umutex_init(&tcb_lock);
  91         if (inited) {
  92                 for (i = 0; i < HASH_QUEUES; ++i)
  93                         LIST_INIT(&thr_hashtable[i]);
  94         }
  95         inited = 1;
  96 }
  97
  98 void
  99 _thr_gc(struct pthread *curthread)
 100 {
 101         struct pthread *td, *td_next;
 102         TAILQ_HEAD(, pthread) worklist;
 103
 104         TAILQ_INIT(&worklist);
 105         THREAD_LIST_WRLOCK(curthread);
 106
 107         /* Check the threads waiting for GC. */
 108         TAILQ_FOREACH_SAFE(td, &_thread_gc_list, gcle, td_next) {
 109                 if (td->tid != TID_TERMINATED) {
 110                         /* make sure we are not still in userland */
 111                         continue;
 112                 }
 113                 _thr_stack_free(&td->attr);
 114                 THR_GCLIST_REMOVE(td);
 115                 TAILQ_INSERT_HEAD(&worklist, td, gcle);
 116         }
 117         THREAD_LIST_UNLOCK(curthread);
 118
 119         while ((td = TAILQ_FIRST(&worklist)) != NULL) {
 120                 TAILQ_REMOVE(&worklist, td, gcle);
 121                 /*
 122                  * XXX we don't free initial thread, because there might
 123                  * have some code referencing initial thread.
 124                  */
 125                 if (td == _thr_initial) {
 126                         DBG_MSG("Initial thread won't be freed\n");
 127                         continue;
 128                 }
 129
 130                 _thr_free(curthread, td);
 131         }
 132 }
 133
 134 struct pthread *
 135 _thr_alloc(struct pthread *curthread)
 136 {
 137         struct pthread  *thread = NULL;
 138         struct tcb      *tcb;
 139
 140         if (curthread != NULL) {
 141                 if (GC_NEEDED())
 142                         _thr_gc(curthread);
 143                 if (free_thread_count > 0) {
 144                         THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 145                         if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 146                                 TAILQ_REMOVE(&free_threadq, thread, tle);
 147                                 free_thread_count--;
 148                         }
 149                         THR_LOCK_RELEASE(curthread, &free_thread_lock);
 150                 }
 151         }
 152         if (thread == NULL) {
 153                 if (total_threads > MAX_THREADS)
 154                         return (NULL);
 155                 atomic_fetchadd_int(&total_threads, 1);
 156                 thread = calloc(1, sizeof(struct pthread));
 157                 if (thread == NULL) {
 158                         atomic_fetchadd_int(&total_threads, -1);
 159                         return (NULL);
 160                 }
 161                 if ((thread->sleepqueue = _sleepq_alloc()) == NULL ||
 162                     (thread->wake_addr = _thr_alloc_wake_addr()) == NULL) {
 163                         thr_destroy(curthread, thread);
 164                         atomic_fetchadd_int(&total_threads, -1);
 165                         return (NULL);
 166                 }
 167         } else {
 168                 bzero(&thread->_pthread_startzero,
 169                         __rangeof(struct pthread, _pthread_startzero, _pthread_endzero));
 170         }
 171         if (curthread != NULL) {
 172                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 173                 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
 174                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 175         } else {
 176                 tcb = _tcb_ctor(thread, 1 /* initial tls */);
 177         }
 178         if (tcb != NULL) {
 179                 thread->tcb = tcb;
 180         } else {
 181                 thr_destroy(curthread, thread);
 182                 atomic_fetchadd_int(&total_threads, -1);
 183                 thread = NULL;
 184         }
 185         return (thread);
 186 }
 187
 188 void
 189 _thr_free(struct pthread *curthread, struct pthread *thread)
 190 {
 191         DBG_MSG("Freeing thread %p\n", thread);
 192
 193         /*
 194          * Always free tcb, as we only know it is part of RTLD TLS
 195          * block, but don't know its detail and can not assume how
 196          * it works, so better to avoid caching it here.
 197          */
 198         if (curthread != NULL) {
 199                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 200                 _tcb_dtor(thread->tcb);
 201                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 202         } else {
 203                 _tcb_dtor(thread->tcb);
 204         }
 205         thread->tcb = NULL;
 206         if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 207                 thr_destroy(curthread, thread);
 208                 atomic_fetchadd_int(&total_threads, -1);
 209         } else {
 210                 /*
 211                  * Add the thread to the free thread list, this also avoids
 212                  * pthread id is reused too quickly, may help some buggy apps.
 213                  */
 214                 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 215                 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 216                 free_thread_count++;
 217                 THR_LOCK_RELEASE(curthread, &free_thread_lock);
 218         }
 219 }
 220
 221 static void
 222 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 223 {
 224         if (thread->sleepqueue != NULL)
 225                 _sleepq_free(thread->sleepqueue);
 226         if (thread->wake_addr != NULL)
 227                 _thr_release_wake_addr(thread->wake_addr);
 228         free(thread);
 229 }
 230
 231 /*
 232  * Add the thread to the list of all threads and increment
 233  * number of active threads.
 234  */
 235 void
 236 _thr_link(struct pthread *curthread, struct pthread *thread)
 237 {
 238         THREAD_LIST_WRLOCK(curthread);
 239         THR_LIST_ADD(thread);
 240         THREAD_LIST_UNLOCK(curthread);
 241         atomic_add_int(&_thread_active_threads, 1);
 242 }
 243
 244 /*
 245  * Remove an active thread.
 246  */
 247 void
 248 _thr_unlink(struct pthread *curthread, struct pthread *thread)
 249 {
 250         THREAD_LIST_WRLOCK(curthread);
 251         THR_LIST_REMOVE(thread);
 252         THREAD_LIST_UNLOCK(curthread);
 253         atomic_add_int(&_thread_active_threads, -1);
 254 }
 255
 256 void
 257 _thr_hash_add(struct pthread *thread)
 258 {
 259         struct thread_hash_head *head;
 260
 261         head = &thr_hashtable[THREAD_HASH(thread)];
 262         LIST_INSERT_HEAD(head, thread, hle);
 263 }
 264
 265 void
 266 _thr_hash_remove(struct pthread *thread)
 267 {
 268         LIST_REMOVE(thread, hle);
 269 }
 270
 271 struct pthread *
 272 _thr_hash_find(struct pthread *thread)
 273 {
 274         struct pthread *td;
 275         struct thread_hash_head *head;
 276
 277         head = &thr_hashtable[THREAD_HASH(thread)];
 278         LIST_FOREACH(td, head, hle) {
 279                 if (td == thread)
 280                         return (thread);
 281         }
 282         return (NULL);
 283 }
 284
 285 /*
 286  * Find a thread in the linked list of active threads and add a reference
 287  * to it.  Threads with positive reference counts will not be deallocated
 288  * until all references are released.
 289  */
 290 int
 291 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
 292     int include_dead)
 293 {
 294         int ret;
 295
 296         if (thread == NULL)
 297                 /* Invalid thread: */
 298                 return (EINVAL);
 299
 300         if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
 301                 thread->refcount++;
 302                 THR_CRITICAL_ENTER(curthread);
 303                 THR_THREAD_UNLOCK(curthread, thread);
 304         }
 305
 306         /* Return zero if the thread exists: */
 307         return (ret);
 308 }
 309
 310 void
 311 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
 312 {
 313         THR_THREAD_LOCK(curthread, thread);
 314         thread->refcount--;
 315         _thr_try_gc(curthread, thread);
 316         THR_CRITICAL_LEAVE(curthread);
 317 }
 318
 319 /* entered with thread lock held, exit with thread lock released */
 320 void
 321 _thr_try_gc(struct pthread *curthread, struct pthread *thread)
 322 {
 323         if (THR_SHOULD_GC(thread)) {
 324                 THR_REF_ADD(curthread, thread);
 325                 THR_THREAD_UNLOCK(curthread, thread);
 326                 THREAD_LIST_WRLOCK(curthread);
 327                 THR_THREAD_LOCK(curthread, thread);
 328                 THR_REF_DEL(curthread, thread);
 329                 if (THR_SHOULD_GC(thread)) {
 330                         THR_LIST_REMOVE(thread);
 331                         THR_GCLIST_ADD(thread);
 332                 }
 333                 THR_THREAD_UNLOCK(curthread, thread);
 334                 THREAD_LIST_UNLOCK(curthread);
 335         } else {
 336                 THR_THREAD_UNLOCK(curthread, thread);
 337         }
 338 }
 339
 340 /* return with thread lock held if thread is found */
 341 int
 342 _thr_find_thread(struct pthread *curthread, struct pthread *thread,
 343     int include_dead)
 344 {
 345         struct pthread *pthread;
 346         int ret;
 347
 348         if (thread == NULL)
 349                 return (EINVAL);
 350
 351         ret = 0;
 352         THREAD_LIST_RDLOCK(curthread);
 353         pthread = _thr_hash_find(thread);
 354         if (pthread) {
 355                 THR_THREAD_LOCK(curthread, pthread);
 356                 if (include_dead == 0 && pthread->state == PS_DEAD) {
 357                         THR_THREAD_UNLOCK(curthread, pthread);
 358                         ret = ESRCH;
 359                 }
 360         } else {
 361                 ret = ESRCH;
 362         }
 363         THREAD_LIST_UNLOCK(curthread);
 364         return (ret);
 365 }
 366
 367 #include "pthread_tls.h"
 368
 369 static void
 370 thr_distribute_static_tls(uintptr_t tlsbase, void *src, size_t len,
 371     size_t total_len)
 372 {
 373
 374         memcpy((void *)tlsbase, src, len);
 375         memset((char *)tlsbase + len, 0, total_len - len);
 376 }
 377
 378 void
 379 __pthread_distribute_static_tls(size_t offset, void *src, size_t len,
 380     size_t total_len)
 381 {
 382         struct pthread *curthread, *thrd;
 383         uintptr_t tlsbase;
 384
 385         if (!_thr_is_inited()) {
 386                 tlsbase = _libc_get_static_tls_base(offset);
 387                 thr_distribute_static_tls(tlsbase, src, len, total_len);
 388                 return;
 389         }
 390         curthread = _get_curthread();
 391         THREAD_LIST_RDLOCK(curthread);
 392         TAILQ_FOREACH(thrd, &_thread_list, tle) {
 393                 tlsbase = _get_static_tls_base(thrd, offset);
 394                 thr_distribute_static_tls(tlsbase, src, len, total_len);
 395         }
 396         THREAD_LIST_UNLOCK(curthread);
 397 }