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