lib/libthr/thread/thr_init.c

   1 /*
   2  * Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
   3  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   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, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by John Birrell.
  17  * 4. Neither the name of the author nor the names of any co-contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $FreeBSD$
  34  */
  35
  36 #include "namespace.h"
  37 #include <sys/types.h>
  38 #include <sys/signalvar.h>
  39 #include <sys/ioctl.h>
  40 #include <sys/link_elf.h>
  41 #include <sys/resource.h>
  42 #include <sys/sysctl.h>
  43 #include <sys/ttycom.h>
  44 #include <sys/mman.h>
  45 #include <sys/rtprio.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <paths.h>
  49 #include <pthread.h>
  50 #include <pthread_np.h>
  51 #include <signal.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <time.h>
  55 #include <unistd.h>
  56 #include "un-namespace.h"
  57
  58 #include "libc_private.h"
  59 #include "thr_private.h"
  60
  61 char            *_usrstack;
  62 struct pthread  *_thr_initial;
  63 int             _libthr_debug;
  64 int             _thread_event_mask;
  65 struct pthread  *_thread_last_event;
  66 pthreadlist     _thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
  67 pthreadlist     _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
  68 int             _thread_active_threads = 1;
  69 atfork_head     _thr_atfork_list = TAILQ_HEAD_INITIALIZER(_thr_atfork_list);
  70 struct urwlock  _thr_atfork_lock = DEFAULT_URWLOCK;
  71
  72 struct pthread_prio     _thr_priorities[3] = {
  73         {RTP_PRIO_MIN,  RTP_PRIO_MAX, 0}, /* FIFO */
  74         {0, 0, 63}, /* OTHER */
  75         {RTP_PRIO_MIN, RTP_PRIO_MAX, 0}  /* RR */
  76 };
  77
  78 struct pthread_attr _pthread_attr_default = {
  79         .sched_policy = SCHED_OTHER,
  80         .sched_inherit = PTHREAD_INHERIT_SCHED,
  81         .prio = 0,
  82         .suspend = THR_CREATE_RUNNING,
  83         .flags = PTHREAD_SCOPE_SYSTEM,
  84         .stackaddr_attr = NULL,
  85         .stacksize_attr = THR_STACK_DEFAULT,
  86         .guardsize_attr = 0,
  87         .cpusetsize = 0,
  88         .cpuset = NULL
  89 };
  90
  91 struct pthread_mutex_attr _pthread_mutexattr_default = {
  92         .m_type = PTHREAD_MUTEX_DEFAULT,
  93         .m_protocol = PTHREAD_PRIO_NONE,
  94         .m_ceiling = 0
  95 };
  96
  97 struct pthread_mutex_attr _pthread_mutexattr_adaptive_default = {
  98         .m_type = PTHREAD_MUTEX_ADAPTIVE_NP,
  99         .m_protocol = PTHREAD_PRIO_NONE,
 100         .m_ceiling = 0
 101 };
 102
 103 /* Default condition variable attributes: */
 104 struct pthread_cond_attr _pthread_condattr_default = {
 105         .c_pshared = PTHREAD_PROCESS_PRIVATE,
 106         .c_clockid = CLOCK_REALTIME
 107 };
 108
 109 int             _thr_is_smp = 0;
 110 size_t          _thr_guard_default;
 111 size_t          _thr_stack_default = THR_STACK_DEFAULT;
 112 size_t          _thr_stack_initial = THR_STACK_INITIAL;
 113 int             _thr_page_size;
 114 int             _thr_spinloops;
 115 int             _thr_yieldloops;
 116 int             _thr_queuefifo = 4;
 117 int             _gc_count;
 118 struct umutex   _mutex_static_lock = DEFAULT_UMUTEX;
 119 struct umutex   _cond_static_lock = DEFAULT_UMUTEX;
 120 struct umutex   _rwlock_static_lock = DEFAULT_UMUTEX;
 121 struct umutex   _keytable_lock = DEFAULT_UMUTEX;
 122 struct urwlock  _thr_list_lock = DEFAULT_URWLOCK;
 123 struct umutex   _thr_event_lock = DEFAULT_UMUTEX;
 124 struct umutex   _suspend_all_lock = DEFAULT_UMUTEX;
 125 struct pthread  *_single_thread;
 126 int             _suspend_all_cycle;
 127 int             _suspend_all_waiters;
 128
 129 int     __pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
 130 int     __pthread_mutex_lock(pthread_mutex_t *);
 131 int     __pthread_mutex_trylock(pthread_mutex_t *);
 132 void    _thread_init_hack(void) __attribute__ ((constructor));
 133
 134 static void init_private(void);
 135 static void init_main_thread(struct pthread *thread);
 136
 137 /*
 138  * All weak references used within libc should be in this table.
 139  * This is so that static libraries will work.
 140  */
 141
 142 STATIC_LIB_REQUIRE(_fork);
 143 STATIC_LIB_REQUIRE(_pthread_getspecific);
 144 STATIC_LIB_REQUIRE(_pthread_key_create);
 145 STATIC_LIB_REQUIRE(_pthread_key_delete);
 146 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
 147 STATIC_LIB_REQUIRE(_pthread_mutex_init);
 148 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
 149 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
 150 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
 151 STATIC_LIB_REQUIRE(_pthread_mutexattr_init);
 152 STATIC_LIB_REQUIRE(_pthread_mutexattr_destroy);
 153 STATIC_LIB_REQUIRE(_pthread_mutexattr_settype);
 154 STATIC_LIB_REQUIRE(_pthread_once);
 155 STATIC_LIB_REQUIRE(_pthread_setspecific);
 156 STATIC_LIB_REQUIRE(_raise);
 157 STATIC_LIB_REQUIRE(_sem_destroy);
 158 STATIC_LIB_REQUIRE(_sem_getvalue);
 159 STATIC_LIB_REQUIRE(_sem_init);
 160 STATIC_LIB_REQUIRE(_sem_post);
 161 STATIC_LIB_REQUIRE(_sem_timedwait);
 162 STATIC_LIB_REQUIRE(_sem_trywait);
 163 STATIC_LIB_REQUIRE(_sem_wait);
 164 STATIC_LIB_REQUIRE(_sigaction);
 165 STATIC_LIB_REQUIRE(_sigprocmask);
 166 STATIC_LIB_REQUIRE(_sigsuspend);
 167 STATIC_LIB_REQUIRE(_sigtimedwait);
 168 STATIC_LIB_REQUIRE(_sigwait);
 169 STATIC_LIB_REQUIRE(_sigwaitinfo);
 170 STATIC_LIB_REQUIRE(_spinlock);
 171 STATIC_LIB_REQUIRE(_spinlock_debug);
 172 STATIC_LIB_REQUIRE(_spinunlock);
 173 STATIC_LIB_REQUIRE(_thread_init_hack);
 174
 175 /*
 176  * These are needed when linking statically.  All references within
 177  * libgcc (and in the future libc) to these routines are weak, but
 178  * if they are not (strongly) referenced by the application or other
 179  * libraries, then the actual functions will not be loaded.
 180  */
 181 STATIC_LIB_REQUIRE(_pthread_once);
 182 STATIC_LIB_REQUIRE(_pthread_key_create);
 183 STATIC_LIB_REQUIRE(_pthread_key_delete);
 184 STATIC_LIB_REQUIRE(_pthread_getspecific);
 185 STATIC_LIB_REQUIRE(_pthread_setspecific);
 186 STATIC_LIB_REQUIRE(_pthread_mutex_init);
 187 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
 188 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
 189 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
 190 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
 191 STATIC_LIB_REQUIRE(_pthread_create);
 192
 193 /* Pull in all symbols required by libthread_db */
 194 STATIC_LIB_REQUIRE(_thread_state_running);
 195
 196 #define DUAL_ENTRY(entry)       \
 197         (pthread_func_t)entry, (pthread_func_t)entry
 198
 199 static pthread_func_t jmp_table[][2] = {
 200         {DUAL_ENTRY(_pthread_atfork)},  /* PJT_ATFORK */
 201         {DUAL_ENTRY(_pthread_attr_destroy)},    /* PJT_ATTR_DESTROY */
 202         {DUAL_ENTRY(_pthread_attr_getdetachstate)},     /* PJT_ATTR_GETDETACHSTATE */
 203         {DUAL_ENTRY(_pthread_attr_getguardsize)},       /* PJT_ATTR_GETGUARDSIZE */
 204         {DUAL_ENTRY(_pthread_attr_getinheritsched)},    /* PJT_ATTR_GETINHERITSCHED */
 205         {DUAL_ENTRY(_pthread_attr_getschedparam)},      /* PJT_ATTR_GETSCHEDPARAM */
 206         {DUAL_ENTRY(_pthread_attr_getschedpolicy)},     /* PJT_ATTR_GETSCHEDPOLICY */
 207         {DUAL_ENTRY(_pthread_attr_getscope)},   /* PJT_ATTR_GETSCOPE */
 208         {DUAL_ENTRY(_pthread_attr_getstackaddr)},       /* PJT_ATTR_GETSTACKADDR */
 209         {DUAL_ENTRY(_pthread_attr_getstacksize)},       /* PJT_ATTR_GETSTACKSIZE */
 210         {DUAL_ENTRY(_pthread_attr_init)},       /* PJT_ATTR_INIT */
 211         {DUAL_ENTRY(_pthread_attr_setdetachstate)},     /* PJT_ATTR_SETDETACHSTATE */
 212         {DUAL_ENTRY(_pthread_attr_setguardsize)},       /* PJT_ATTR_SETGUARDSIZE */
 213         {DUAL_ENTRY(_pthread_attr_setinheritsched)},    /* PJT_ATTR_SETINHERITSCHED */
 214         {DUAL_ENTRY(_pthread_attr_setschedparam)},      /* PJT_ATTR_SETSCHEDPARAM */
 215         {DUAL_ENTRY(_pthread_attr_setschedpolicy)},     /* PJT_ATTR_SETSCHEDPOLICY */
 216         {DUAL_ENTRY(_pthread_attr_setscope)},   /* PJT_ATTR_SETSCOPE */
 217         {DUAL_ENTRY(_pthread_attr_setstackaddr)},       /* PJT_ATTR_SETSTACKADDR */
 218         {DUAL_ENTRY(_pthread_attr_setstacksize)},       /* PJT_ATTR_SETSTACKSIZE */
 219         {DUAL_ENTRY(_pthread_cancel)},  /* PJT_CANCEL */
 220         {DUAL_ENTRY(_pthread_cleanup_pop)},     /* PJT_CLEANUP_POP */
 221         {DUAL_ENTRY(_pthread_cleanup_push)},    /* PJT_CLEANUP_PUSH */
 222         {DUAL_ENTRY(_pthread_cond_broadcast)},  /* PJT_COND_BROADCAST */
 223         {DUAL_ENTRY(_pthread_cond_destroy)},    /* PJT_COND_DESTROY */
 224         {DUAL_ENTRY(_pthread_cond_init)},       /* PJT_COND_INIT */
 225         {DUAL_ENTRY(_pthread_cond_signal)},     /* PJT_COND_SIGNAL */
 226         {DUAL_ENTRY(_pthread_cond_timedwait)},  /* PJT_COND_TIMEDWAIT */
 227         {(pthread_func_t)__pthread_cond_wait,
 228          (pthread_func_t)_pthread_cond_wait},   /* PJT_COND_WAIT */
 229         {DUAL_ENTRY(_pthread_detach)},  /* PJT_DETACH */
 230         {DUAL_ENTRY(_pthread_equal)},   /* PJT_EQUAL */
 231         {DUAL_ENTRY(_pthread_exit)},    /* PJT_EXIT */
 232         {DUAL_ENTRY(_pthread_getspecific)},     /* PJT_GETSPECIFIC */
 233         {DUAL_ENTRY(_pthread_join)},    /* PJT_JOIN */
 234         {DUAL_ENTRY(_pthread_key_create)},      /* PJT_KEY_CREATE */
 235         {DUAL_ENTRY(_pthread_key_delete)},      /* PJT_KEY_DELETE*/
 236         {DUAL_ENTRY(_pthread_kill)},    /* PJT_KILL */
 237         {DUAL_ENTRY(_pthread_main_np)},         /* PJT_MAIN_NP */
 238         {DUAL_ENTRY(_pthread_mutexattr_destroy)}, /* PJT_MUTEXATTR_DESTROY */
 239         {DUAL_ENTRY(_pthread_mutexattr_init)},  /* PJT_MUTEXATTR_INIT */
 240         {DUAL_ENTRY(_pthread_mutexattr_settype)}, /* PJT_MUTEXATTR_SETTYPE */
 241         {DUAL_ENTRY(_pthread_mutex_destroy)},   /* PJT_MUTEX_DESTROY */
 242         {DUAL_ENTRY(_pthread_mutex_init)},      /* PJT_MUTEX_INIT */
 243         {(pthread_func_t)__pthread_mutex_lock,
 244          (pthread_func_t)_pthread_mutex_lock},  /* PJT_MUTEX_LOCK */
 245         {(pthread_func_t)__pthread_mutex_trylock,
 246          (pthread_func_t)_pthread_mutex_trylock},/* PJT_MUTEX_TRYLOCK */
 247         {DUAL_ENTRY(_pthread_mutex_unlock)},    /* PJT_MUTEX_UNLOCK */
 248         {DUAL_ENTRY(_pthread_once)},            /* PJT_ONCE */
 249         {DUAL_ENTRY(_pthread_rwlock_destroy)},  /* PJT_RWLOCK_DESTROY */
 250         {DUAL_ENTRY(_pthread_rwlock_init)},     /* PJT_RWLOCK_INIT */
 251         {DUAL_ENTRY(_pthread_rwlock_rdlock)},   /* PJT_RWLOCK_RDLOCK */
 252         {DUAL_ENTRY(_pthread_rwlock_tryrdlock)},/* PJT_RWLOCK_TRYRDLOCK */
 253         {DUAL_ENTRY(_pthread_rwlock_trywrlock)},/* PJT_RWLOCK_TRYWRLOCK */
 254         {DUAL_ENTRY(_pthread_rwlock_unlock)},   /* PJT_RWLOCK_UNLOCK */
 255         {DUAL_ENTRY(_pthread_rwlock_wrlock)},   /* PJT_RWLOCK_WRLOCK */
 256         {DUAL_ENTRY(_pthread_self)},            /* PJT_SELF */
 257         {DUAL_ENTRY(_pthread_setcancelstate)},  /* PJT_SETCANCELSTATE */
 258         {DUAL_ENTRY(_pthread_setcanceltype)},   /* PJT_SETCANCELTYPE */
 259         {DUAL_ENTRY(_pthread_setspecific)},     /* PJT_SETSPECIFIC */
 260         {DUAL_ENTRY(_pthread_sigmask)},         /* PJT_SIGMASK */
 261         {DUAL_ENTRY(_pthread_testcancel)},      /* PJT_TESTCANCEL */
 262         {DUAL_ENTRY(__pthread_cleanup_pop_imp)},/* PJT_CLEANUP_POP_IMP */
 263         {DUAL_ENTRY(__pthread_cleanup_push_imp)},/* PJT_CLEANUP_PUSH_IMP */
 264         {DUAL_ENTRY(_pthread_cancel_enter)},    /* PJT_CANCEL_ENTER */
 265         {DUAL_ENTRY(_pthread_cancel_leave)}             /* PJT_CANCEL_LEAVE */
 266 };
 267
 268 static int init_once = 0;
 269
 270 /*
 271  * For the shared version of the threads library, the above is sufficient.
 272  * But for the archive version of the library, we need a little bit more.
 273  * Namely, we must arrange for this particular module to be pulled in from
 274  * the archive library at link time.  To accomplish that, we define and
 275  * initialize a variable, "_thread_autoinit_dummy_decl".  This variable is
 276  * referenced (as an extern) from libc/stdlib/exit.c. This will always
 277  * create a need for this module, ensuring that it is present in the
 278  * executable.
 279  */
 280 extern int _thread_autoinit_dummy_decl;
 281 int _thread_autoinit_dummy_decl = 0;
 282
 283 void
 284 _thread_init_hack(void)
 285 {
 286
 287         _libpthread_init(NULL);
 288 }
 289
 290
 291 /*
 292  * Threaded process initialization.
 293  *
 294  * This is only called under two conditions:
 295  *
 296  *   1) Some thread routines have detected that the library hasn't yet
 297  *      been initialized (_thr_initial == NULL && curthread == NULL), or
 298  *
 299  *   2) An explicit call to reinitialize after a fork (indicated
 300  *      by curthread != NULL)
 301  */
 302 void
 303 _libpthread_init(struct pthread *curthread)
 304 {
 305         int first, dlopened;
 306
 307         /* Check if this function has already been called: */
 308         if ((_thr_initial != NULL) && (curthread == NULL))
 309                 /* Only initialize the threaded application once. */
 310                 return;
 311
 312         /*
 313          * Check the size of the jump table to make sure it is preset
 314          * with the correct number of entries.
 315          */
 316         if (sizeof(jmp_table) != (sizeof(pthread_func_t) * PJT_MAX * 2))
 317                 PANIC("Thread jump table not properly initialized");
 318         memcpy(__thr_jtable, jmp_table, sizeof(jmp_table));
 319         __thr_interpose_libc();
 320
 321         /* Initialize pthread private data. */
 322         init_private();
 323
 324         /* Set the initial thread. */
 325         if (curthread == NULL) {
 326                 first = 1;
 327                 /* Create and initialize the initial thread. */
 328                 curthread = _thr_alloc(NULL);
 329                 if (curthread == NULL)
 330                         PANIC("Can't allocate initial thread");
 331                 init_main_thread(curthread);
 332         } else {
 333                 first = 0;
 334         }
 335
 336         /*
 337          * Add the thread to the thread list queue.
 338          */
 339         THR_LIST_ADD(curthread);
 340         _thread_active_threads = 1;
 341
 342         /* Setup the thread specific data */
 343         _tcb_set(curthread->tcb);
 344
 345         if (first) {
 346                 _thr_initial = curthread;
 347                 dlopened = _rtld_is_dlopened(&_thread_autoinit_dummy_decl) != 0;
 348                 _thr_signal_init(dlopened);
 349                 if (_thread_event_mask & TD_CREATE)
 350                         _thr_report_creation(curthread, curthread);
 351                 /*
 352                  * Always use our rtld lock implementation.
 353                  * It is faster because it postpones signal handlers
 354                  * instead of calling sigprocmask(2).
 355                  */
 356                 _thr_rtld_init();
 357         }
 358 }
 359
 360 /*
 361  * This function and pthread_create() do a lot of the same things.
 362  * It'd be nice to consolidate the common stuff in one place.
 363  */
 364 static void
 365 init_main_thread(struct pthread *thread)
 366 {
 367         struct sched_param sched_param;
 368
 369         /* Setup the thread attributes. */
 370         thr_self(&thread->tid);
 371         thread->attr = _pthread_attr_default;
 372         /*
 373          * Set up the thread stack.
 374          *
 375          * Create a red zone below the main stack.  All other stacks
 376          * are constrained to a maximum size by the parameters
 377          * passed to mmap(), but this stack is only limited by
 378          * resource limits, so this stack needs an explicitly mapped
 379          * red zone to protect the thread stack that is just beyond.
 380          */
 381         if (mmap(_usrstack - _thr_stack_initial -
 382             _thr_guard_default, _thr_guard_default, 0, MAP_ANON,
 383             -1, 0) == MAP_FAILED)
 384                 PANIC("Cannot allocate red zone for initial thread");
 385
 386         /*
 387          * Mark the stack as an application supplied stack so that it
 388          * isn't deallocated.
 389          *
 390          * XXX - I'm not sure it would hurt anything to deallocate
 391          *       the main thread stack because deallocation doesn't
 392          *       actually free() it; it just puts it in the free
 393          *       stack queue for later reuse.
 394          */
 395         thread->attr.stackaddr_attr = _usrstack - _thr_stack_initial;
 396         thread->attr.stacksize_attr = _thr_stack_initial;
 397         thread->attr.guardsize_attr = _thr_guard_default;
 398         thread->attr.flags |= THR_STACK_USER;
 399
 400         /*
 401          * Write a magic value to the thread structure
 402          * to help identify valid ones:
 403          */
 404         thread->magic = THR_MAGIC;
 405
 406         thread->cancel_enable = 1;
 407         thread->cancel_async = 0;
 408
 409         /* Initialize the mutex queue: */
 410         TAILQ_INIT(&thread->mutexq);
 411         TAILQ_INIT(&thread->pp_mutexq);
 412
 413         thread->state = PS_RUNNING;
 414
 415         _thr_getscheduler(thread->tid, &thread->attr.sched_policy,
 416                  &sched_param);
 417         thread->attr.prio = sched_param.sched_priority;
 418
 419 #ifdef _PTHREAD_FORCED_UNWIND
 420         thread->unwind_stackend = _usrstack;
 421 #endif
 422
 423         /* Others cleared to zero by thr_alloc() */
 424 }
 425
 426 static void
 427 init_private(void)
 428 {
 429         struct rlimit rlim;
 430         size_t len;
 431         int mib[2];
 432         char *env, *env_bigstack, *env_splitstack;
 433
 434         _thr_umutex_init(&_mutex_static_lock);
 435         _thr_umutex_init(&_cond_static_lock);
 436         _thr_umutex_init(&_rwlock_static_lock);
 437         _thr_umutex_init(&_keytable_lock);
 438         _thr_urwlock_init(&_thr_atfork_lock);
 439         _thr_umutex_init(&_thr_event_lock);
 440         _thr_umutex_init(&_suspend_all_lock);
 441         _thr_spinlock_init();
 442         _thr_list_init();
 443         _thr_wake_addr_init();
 444         _sleepq_init();
 445         _single_thread = NULL;
 446         _suspend_all_waiters = 0;
 447
 448         /*
 449          * Avoid reinitializing some things if they don't need to be,
 450          * e.g. after a fork().
 451          */
 452         if (init_once == 0) {
 453                 /* Find the stack top */
 454                 mib[0] = CTL_KERN;
 455                 mib[1] = KERN_USRSTACK;
 456                 len = sizeof (_usrstack);
 457                 if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
 458                         PANIC("Cannot get kern.usrstack from sysctl");
 459                 env_bigstack = getenv("LIBPTHREAD_BIGSTACK_MAIN");
 460                 env_splitstack = getenv("LIBPTHREAD_SPLITSTACK_MAIN");
 461                 if (env_bigstack != NULL || env_splitstack == NULL) {
 462                         if (getrlimit(RLIMIT_STACK, &rlim) == -1)
 463                                 PANIC("Cannot get stack rlimit");
 464                         _thr_stack_initial = rlim.rlim_cur;
 465                 }
 466                 len = sizeof(_thr_is_smp);
 467                 sysctlbyname("kern.smp.cpus", &_thr_is_smp, &len, NULL, 0);
 468                 _thr_is_smp = (_thr_is_smp > 1);
 469                 _thr_page_size = getpagesize();
 470                 _thr_guard_default = _thr_page_size;
 471                 _pthread_attr_default.guardsize_attr = _thr_guard_default;
 472                 _pthread_attr_default.stacksize_attr = _thr_stack_default;
 473                 env = getenv("LIBPTHREAD_SPINLOOPS");
 474                 if (env)
 475                         _thr_spinloops = atoi(env);
 476                 env = getenv("LIBPTHREAD_YIELDLOOPS");
 477                 if (env)
 478                         _thr_yieldloops = atoi(env);
 479                 env = getenv("LIBPTHREAD_QUEUE_FIFO");
 480                 if (env)
 481                         _thr_queuefifo = atoi(env);
 482                 TAILQ_INIT(&_thr_atfork_list);
 483         }
 484         init_once = 1;
 485 }