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