lib/libthread_xu/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/types.h>
  29 #include <sys/queue.h>
  30
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <pthread.h>
  34
  35 #include "libc_private.h"
  36 #include "thr_private.h"
  37
  38 /* #define DEBUG_THREAD_LIST */
  39 #ifdef DEBUG_THREAD_LIST
  40 #define DBG_MSG         stdout_debug
  41 #else
  42 #define DBG_MSG(x...)
  43 #endif
  44
  45 /* List of all threads */
  46 struct thread_head _thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
  47
  48 /* List of threads needing GC */
  49 struct thread_head _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
  50
  51 /* Number of active threads */
  52 int     _thread_active_threads = 1;
  53
  54 /* Garbage thread count. */
  55 int     _thr_gc_count;
  56
  57 umtx_t  _thr_list_lock;
  58
  59 /*
  60  * Define a high water mark for the maximum number of threads that
  61  * will be cached.  Once this level is reached, any extra threads
  62  * will be free()'d.
  63  */
  64 #define MAX_CACHED_THREADS      100
  65
  66 /*
  67  * We've got to keep track of everything that is allocated, not only
  68  * to have a speedy free list, but also so they can be deallocated
  69  * after a fork().
  70  */
  71 static TAILQ_HEAD(, pthread)    free_threadq;
  72 static umtx_t                   free_thread_lock;
  73 static umtx_t                   tcb_lock;
  74 static int                      free_thread_count = 0;
  75 static int                      inited = 0;
  76 static u_int64_t                next_uniqueid = 1;
  77
  78 LIST_HEAD(thread_hash_head, pthread);
  79 #define HASH_QUEUES     128
  80 static struct thread_hash_head  thr_hashtable[HASH_QUEUES];
  81 #define THREAD_HASH(thrd)       (((unsigned long)thrd >> 12) % HASH_QUEUES)
  82
  83 static void thr_destroy(struct pthread *curthread, struct pthread *thread);
  84
  85 void
  86 _thr_list_init(void)
  87 {
  88         int i;
  89
  90         _thr_gc_count = 0;
  91         _thr_umtx_init(&_thr_list_lock);
  92         TAILQ_INIT(&_thread_list);
  93         TAILQ_INIT(&free_threadq);
  94         _thr_umtx_init(&free_thread_lock);
  95         _thr_umtx_init(&tcb_lock);
  96         if (inited) {
  97                 for (i = 0; i < HASH_QUEUES; ++i)
  98                         LIST_INIT(&thr_hashtable[i]);
  99         }
 100         inited = 1;
 101 }
 102
 103 void
 104 _thr_gc(struct pthread *curthread)
 105 {
 106         struct pthread *td, *td_next;
 107         TAILQ_HEAD(, pthread) worklist;
 108
 109         TAILQ_INIT(&worklist);
 110         THREAD_LIST_LOCK(curthread);
 111
 112         /* Check the threads waiting for GC. */
 113         for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) {
 114                 td_next = TAILQ_NEXT(td, gcle);
 115                 if (td->terminated == 0) {
 116                         /* make sure we are not still in userland */
 117                         continue;
 118                 }
 119                 _thr_stack_free(&td->attr);
 120                 if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
 121                     (td->refcount == 0)) {
 122                         THR_GCLIST_REMOVE(td);
 123                         /*
 124                          * The thread has detached and is no longer
 125                          * referenced.  It is safe to remove all
 126                          * remnants of the thread.
 127                          */
 128                         THR_LIST_REMOVE(td);
 129                         TAILQ_INSERT_HEAD(&worklist, td, gcle);
 130                 }
 131         }
 132         THREAD_LIST_UNLOCK(curthread);
 133
 134         while ((td = TAILQ_FIRST(&worklist)) != NULL) {
 135                 TAILQ_REMOVE(&worklist, td, gcle);
 136                 /*
 137                  * XXX we don't free initial thread, because there might
 138                  * have some code referencing initial thread.
 139                  */
 140                 if (td == _thr_initial) {
 141                         DBG_MSG("Initial thread won't be freed\n");
 142                         continue;
 143                 }
 144
 145                 _thr_free(curthread, td);
 146         }
 147 }
 148
 149 struct pthread *
 150 _thr_alloc(struct pthread *curthread)
 151 {
 152         struct pthread  *thread = NULL;
 153         struct tls_tcb  *tcb;
 154
 155         if (curthread != NULL) {
 156                 if (GC_NEEDED())
 157                         _thr_gc(curthread);
 158                 if (free_thread_count > 0) {
 159                         THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 160                         if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
 161                                 TAILQ_REMOVE(&free_threadq, thread, tle);
 162                                 free_thread_count--;
 163                         }
 164                         THR_LOCK_RELEASE(curthread, &free_thread_lock);
 165                 }
 166         }
 167         if (thread == NULL) {
 168                 thread = malloc(sizeof(struct pthread));
 169                 if (thread == NULL)
 170                         return (NULL);
 171         }
 172         if (curthread != NULL) {
 173                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 174                 tcb = _tcb_ctor(thread, 0 /* not initial tls */);
 175                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 176         } else {
 177                 tcb = _tcb_ctor(thread, 1 /* initial tls */);
 178         }
 179         if (tcb != NULL) {
 180                 memset(thread, 0, sizeof(*thread));
 181                 thread->tcb = tcb;
 182         } else {
 183                 thr_destroy(curthread, thread);
 184                 thread = NULL;
 185         }
 186         return (thread);
 187 }
 188
 189 void
 190 _thr_free(struct pthread *curthread, struct pthread *thread)
 191 {
 192         DBG_MSG("Freeing thread %p\n", thread);
 193         if (thread->name) {
 194                 free(thread->name);
 195                 thread->name = NULL;
 196         }
 197         /*
 198          * Always free tcb, as we only know it is part of RTLD TLS
 199          * block, but don't know its detail and can not assume how
 200          * it works, so better to avoid caching it here.
 201          */
 202         if (curthread != NULL) {
 203                 THR_LOCK_ACQUIRE(curthread, &tcb_lock);
 204                 _tcb_dtor(thread->tcb);
 205                 THR_LOCK_RELEASE(curthread, &tcb_lock);
 206         } else {
 207                 _tcb_dtor(thread->tcb);
 208         }
 209         thread->tcb = NULL;
 210         if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
 211                 thr_destroy(curthread, thread);
 212         } else {
 213                 /*
 214                  * Add the thread to the free thread list, this also avoids
 215                  * pthread id is reused too quickly, may help some buggy apps.
 216                  */
 217                 THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
 218                 TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
 219                 free_thread_count++;
 220                 THR_LOCK_RELEASE(curthread, &free_thread_lock);
 221         }
 222 }
 223
 224 static void
 225 thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
 226 {
 227         free(thread);
 228 }
 229
 230 /*
 231  * Add an active thread:
 232  *
 233  *   o Assign the thread a unique id (which GDB uses to track
 234  *     threads.
 235  *   o Add the thread to the list of all threads and increment
 236  *     number of active threads.
 237  */
 238 void
 239 _thr_link(struct pthread *curthread, struct pthread *thread)
 240 {
 241         THREAD_LIST_LOCK(curthread);
 242         /*
 243          * Initialize the unique id (which GDB uses to track
 244          * threads), add the thread to the list of all threads,
 245          * and
 246          */
 247         thread->uniqueid = next_uniqueid++;
 248         THR_LIST_ADD(thread);
 249         _thread_active_threads++;
 250         THREAD_LIST_UNLOCK(curthread);
 251 }
 252
 253 /*
 254  * Remove an active thread.
 255  */
 256 void
 257 _thr_unlink(struct pthread *curthread, struct pthread *thread)
 258 {
 259         THREAD_LIST_LOCK(curthread);
 260         THR_LIST_REMOVE(thread);
 261         _thread_active_threads--;
 262         THREAD_LIST_UNLOCK(curthread);
 263 }
 264
 265 void
 266 _thr_hash_add(struct pthread *thread)
 267 {
 268         struct thread_hash_head *head;
 269
 270         head = &thr_hashtable[THREAD_HASH(thread)];
 271         LIST_INSERT_HEAD(head, thread, hle);
 272 }
 273
 274 void
 275 _thr_hash_remove(struct pthread *thread)
 276 {
 277         LIST_REMOVE(thread, hle);
 278 }
 279
 280 struct pthread *
 281 _thr_hash_find(struct pthread *thread)
 282 {
 283         struct pthread *td;
 284         struct thread_hash_head *head;
 285
 286         head = &thr_hashtable[THREAD_HASH(thread)];
 287         LIST_FOREACH(td, head, hle) {
 288                 if (td == thread)
 289                         return (thread);
 290         }
 291         return (NULL);
 292 }
 293
 294 /*
 295  * Find a thread in the linked list of active threads and add a reference
 296  * to it.  Threads with positive reference counts will not be deallocated
 297  * until all references are released.
 298  */
 299 int
 300 _thr_ref_add(struct pthread *curthread, struct pthread *thread,
 301     int include_dead)
 302 {
 303         int ret;
 304
 305         if (thread == NULL)
 306                 /* Invalid thread: */
 307                 return (EINVAL);
 308
 309         THREAD_LIST_LOCK(curthread);
 310         if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
 311                 thread->refcount++;
 312         }
 313         THREAD_LIST_UNLOCK(curthread);
 314
 315         /* Return zero if the thread exists: */
 316         return (ret);
 317 }
 318
 319 void
 320 _thr_ref_delete(struct pthread *curthread, struct pthread *thread)
 321 {
 322         THREAD_LIST_LOCK(curthread);
 323         _thr_ref_delete_unlocked(curthread, thread);
 324         THREAD_LIST_UNLOCK(curthread);
 325 }
 326
 327 void
 328 _thr_ref_delete_unlocked(struct pthread *curthread __unused,
 329         struct pthread *thread)
 330 {
 331         if (thread != NULL) {
 332                 thread->refcount--;
 333                 if ((thread->refcount == 0) && thread->state == PS_DEAD &&
 334                     (thread->tlflags & TLFLAGS_DETACHED) != 0)
 335                         THR_GCLIST_ADD(thread);
 336         }
 337 }
 338
 339 int
 340 _thr_find_thread(struct pthread *curthread __unused, struct pthread *thread,
 341     int include_dead)
 342 {
 343         struct pthread *pthread;
 344
 345         if (thread == NULL)
 346                 return (EINVAL);
 347
 348         pthread = _thr_hash_find(thread);
 349         if (pthread) {
 350                 if (include_dead == 0 && pthread->state == PS_DEAD) {
 351                         pthread = NULL;
 352                 }
 353         }
 354
 355         /* Return zero if the thread exists: */
 356         return ((pthread != NULL) ? 0 : ESRCH);
 357 }