xref: /freebsd/lib/libthr/thread/thr_init.c (revision fb47a3769c514735bceb2822a64e5e70c3d2f7a4)
1 /*-
2  * SPDX-License-Identifier: BSD-4-Clause
3  *
4  * Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
5  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
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, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by John Birrell.
19  * 4. Neither the name of the author nor the names of any co-contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 #include "namespace.h"
40 #include <sys/types.h>
41 #include <sys/signalvar.h>
42 #include <sys/ioctl.h>
43 #include <sys/link_elf.h>
44 #include <sys/resource.h>
45 #include <sys/sysctl.h>
46 #include <sys/ttycom.h>
47 #include <sys/mman.h>
48 #include <sys/rtprio.h>
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <paths.h>
52 #include <pthread.h>
53 #include <pthread_np.h>
54 #include <signal.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <time.h>
58 #include <unistd.h>
59 #include "un-namespace.h"
60 
61 #include "libc_private.h"
62 #include "thr_private.h"
63 
64 char		*_usrstack;
65 struct pthread	*_thr_initial;
66 int		_libthr_debug;
67 int		_thread_event_mask;
68 struct pthread	*_thread_last_event;
69 pthreadlist	_thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
70 pthreadlist 	_thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
71 int		_thread_active_threads = 1;
72 atfork_head	_thr_atfork_list = TAILQ_HEAD_INITIALIZER(_thr_atfork_list);
73 struct urwlock	_thr_atfork_lock = DEFAULT_URWLOCK;
74 
75 struct pthread_prio	_thr_priorities[3] = {
76 	{RTP_PRIO_MIN,  RTP_PRIO_MAX, 0}, /* FIFO */
77 	{0, 0, 63}, /* OTHER */
78 	{RTP_PRIO_MIN, RTP_PRIO_MAX, 0}  /* RR */
79 };
80 
81 struct pthread_attr _pthread_attr_default = {
82 	.sched_policy = SCHED_OTHER,
83 	.sched_inherit = PTHREAD_INHERIT_SCHED,
84 	.prio = 0,
85 	.suspend = THR_CREATE_RUNNING,
86 	.flags = PTHREAD_SCOPE_SYSTEM,
87 	.stackaddr_attr = NULL,
88 	.stacksize_attr = THR_STACK_DEFAULT,
89 	.guardsize_attr = 0,
90 	.cpusetsize = 0,
91 	.cpuset = NULL
92 };
93 
94 struct pthread_mutex_attr _pthread_mutexattr_default = {
95 	.m_type = PTHREAD_MUTEX_DEFAULT,
96 	.m_protocol = PTHREAD_PRIO_NONE,
97 	.m_ceiling = 0,
98 	.m_pshared = PTHREAD_PROCESS_PRIVATE,
99 	.m_robust = PTHREAD_MUTEX_STALLED,
100 };
101 
102 struct pthread_mutex_attr _pthread_mutexattr_adaptive_default = {
103 	.m_type = PTHREAD_MUTEX_ADAPTIVE_NP,
104 	.m_protocol = PTHREAD_PRIO_NONE,
105 	.m_ceiling = 0,
106 	.m_pshared = PTHREAD_PROCESS_PRIVATE,
107 	.m_robust = PTHREAD_MUTEX_STALLED,
108 };
109 
110 /* Default condition variable attributes: */
111 struct pthread_cond_attr _pthread_condattr_default = {
112 	.c_pshared = PTHREAD_PROCESS_PRIVATE,
113 	.c_clockid = CLOCK_REALTIME
114 };
115 
116 int		_thr_is_smp = 0;
117 size_t		_thr_guard_default;
118 size_t		_thr_stack_default = THR_STACK_DEFAULT;
119 size_t		_thr_stack_initial = THR_STACK_INITIAL;
120 int		_thr_page_size;
121 int		_thr_spinloops;
122 int		_thr_yieldloops;
123 int		_thr_queuefifo = 4;
124 int		_gc_count;
125 struct umutex	_mutex_static_lock = DEFAULT_UMUTEX;
126 struct umutex	_cond_static_lock = DEFAULT_UMUTEX;
127 struct umutex	_rwlock_static_lock = DEFAULT_UMUTEX;
128 struct umutex	_keytable_lock = DEFAULT_UMUTEX;
129 struct urwlock	_thr_list_lock = DEFAULT_URWLOCK;
130 struct umutex	_thr_event_lock = DEFAULT_UMUTEX;
131 struct umutex	_suspend_all_lock = DEFAULT_UMUTEX;
132 struct pthread	*_single_thread;
133 int		_suspend_all_cycle;
134 int		_suspend_all_waiters;
135 
136 int	__pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
137 int	__pthread_mutex_lock(pthread_mutex_t *);
138 int	__pthread_mutex_trylock(pthread_mutex_t *);
139 void	_thread_init_hack(void) __attribute__ ((constructor));
140 
141 static void init_private(void);
142 static void init_main_thread(struct pthread *thread);
143 
144 /*
145  * All weak references used within libc should be in this table.
146  * This is so that static libraries will work.
147  */
148 
149 STATIC_LIB_REQUIRE(_fork);
150 STATIC_LIB_REQUIRE(_pthread_getspecific);
151 STATIC_LIB_REQUIRE(_pthread_key_create);
152 STATIC_LIB_REQUIRE(_pthread_key_delete);
153 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
154 STATIC_LIB_REQUIRE(_pthread_mutex_init);
155 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
156 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
157 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
158 STATIC_LIB_REQUIRE(_pthread_mutexattr_init);
159 STATIC_LIB_REQUIRE(_pthread_mutexattr_destroy);
160 STATIC_LIB_REQUIRE(_pthread_mutexattr_settype);
161 STATIC_LIB_REQUIRE(_pthread_once);
162 STATIC_LIB_REQUIRE(_pthread_setspecific);
163 STATIC_LIB_REQUIRE(_raise);
164 STATIC_LIB_REQUIRE(_sem_destroy);
165 STATIC_LIB_REQUIRE(_sem_getvalue);
166 STATIC_LIB_REQUIRE(_sem_init);
167 STATIC_LIB_REQUIRE(_sem_post);
168 STATIC_LIB_REQUIRE(_sem_timedwait);
169 STATIC_LIB_REQUIRE(_sem_trywait);
170 STATIC_LIB_REQUIRE(_sem_wait);
171 STATIC_LIB_REQUIRE(_sigaction);
172 STATIC_LIB_REQUIRE(_sigprocmask);
173 STATIC_LIB_REQUIRE(_sigsuspend);
174 STATIC_LIB_REQUIRE(_sigtimedwait);
175 STATIC_LIB_REQUIRE(_sigwait);
176 STATIC_LIB_REQUIRE(_sigwaitinfo);
177 STATIC_LIB_REQUIRE(_spinlock);
178 STATIC_LIB_REQUIRE(_spinunlock);
179 STATIC_LIB_REQUIRE(_thread_init_hack);
180 
181 /*
182  * These are needed when linking statically.  All references within
183  * libgcc (and in the future libc) to these routines are weak, but
184  * if they are not (strongly) referenced by the application or other
185  * libraries, then the actual functions will not be loaded.
186  */
187 STATIC_LIB_REQUIRE(_pthread_once);
188 STATIC_LIB_REQUIRE(_pthread_key_create);
189 STATIC_LIB_REQUIRE(_pthread_key_delete);
190 STATIC_LIB_REQUIRE(_pthread_getspecific);
191 STATIC_LIB_REQUIRE(_pthread_setspecific);
192 STATIC_LIB_REQUIRE(_pthread_mutex_init);
193 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
194 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
195 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
196 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
197 STATIC_LIB_REQUIRE(_pthread_create);
198 
199 /* Pull in all symbols required by libthread_db */
200 STATIC_LIB_REQUIRE(_thread_state_running);
201 
202 #define	DUAL_ENTRY(entry)	\
203 	(pthread_func_t)entry, (pthread_func_t)entry
204 
205 static pthread_func_t jmp_table[][2] = {
206 	{DUAL_ENTRY(_pthread_atfork)},	/* PJT_ATFORK */
207 	{DUAL_ENTRY(_pthread_attr_destroy)},	/* PJT_ATTR_DESTROY */
208 	{DUAL_ENTRY(_pthread_attr_getdetachstate)},	/* PJT_ATTR_GETDETACHSTATE */
209 	{DUAL_ENTRY(_pthread_attr_getguardsize)},	/* PJT_ATTR_GETGUARDSIZE */
210 	{DUAL_ENTRY(_pthread_attr_getinheritsched)},	/* PJT_ATTR_GETINHERITSCHED */
211 	{DUAL_ENTRY(_pthread_attr_getschedparam)},	/* PJT_ATTR_GETSCHEDPARAM */
212 	{DUAL_ENTRY(_pthread_attr_getschedpolicy)},	/* PJT_ATTR_GETSCHEDPOLICY */
213 	{DUAL_ENTRY(_pthread_attr_getscope)},	/* PJT_ATTR_GETSCOPE */
214 	{DUAL_ENTRY(_pthread_attr_getstackaddr)},	/* PJT_ATTR_GETSTACKADDR */
215 	{DUAL_ENTRY(_pthread_attr_getstacksize)},	/* PJT_ATTR_GETSTACKSIZE */
216 	{DUAL_ENTRY(_pthread_attr_init)},	/* PJT_ATTR_INIT */
217 	{DUAL_ENTRY(_pthread_attr_setdetachstate)},	/* PJT_ATTR_SETDETACHSTATE */
218 	{DUAL_ENTRY(_pthread_attr_setguardsize)},	/* PJT_ATTR_SETGUARDSIZE */
219 	{DUAL_ENTRY(_pthread_attr_setinheritsched)},	/* PJT_ATTR_SETINHERITSCHED */
220 	{DUAL_ENTRY(_pthread_attr_setschedparam)},	/* PJT_ATTR_SETSCHEDPARAM */
221 	{DUAL_ENTRY(_pthread_attr_setschedpolicy)},	/* PJT_ATTR_SETSCHEDPOLICY */
222 	{DUAL_ENTRY(_pthread_attr_setscope)},	/* PJT_ATTR_SETSCOPE */
223 	{DUAL_ENTRY(_pthread_attr_setstackaddr)},	/* PJT_ATTR_SETSTACKADDR */
224 	{DUAL_ENTRY(_pthread_attr_setstacksize)},	/* PJT_ATTR_SETSTACKSIZE */
225 	{DUAL_ENTRY(_pthread_cancel)},	/* PJT_CANCEL */
226 	{DUAL_ENTRY(_pthread_cleanup_pop)},	/* PJT_CLEANUP_POP */
227 	{DUAL_ENTRY(_pthread_cleanup_push)},	/* PJT_CLEANUP_PUSH */
228 	{DUAL_ENTRY(_pthread_cond_broadcast)},	/* PJT_COND_BROADCAST */
229 	{DUAL_ENTRY(_pthread_cond_destroy)},	/* PJT_COND_DESTROY */
230 	{DUAL_ENTRY(_pthread_cond_init)},	/* PJT_COND_INIT */
231 	{DUAL_ENTRY(_pthread_cond_signal)},	/* PJT_COND_SIGNAL */
232 	{DUAL_ENTRY(_pthread_cond_timedwait)},	/* PJT_COND_TIMEDWAIT */
233 	{(pthread_func_t)__pthread_cond_wait,
234 	 (pthread_func_t)_pthread_cond_wait},	/* PJT_COND_WAIT */
235 	{DUAL_ENTRY(_pthread_detach)},	/* PJT_DETACH */
236 	{DUAL_ENTRY(_pthread_equal)},	/* PJT_EQUAL */
237 	{DUAL_ENTRY(_pthread_exit)},	/* PJT_EXIT */
238 	{DUAL_ENTRY(_pthread_getspecific)},	/* PJT_GETSPECIFIC */
239 	{DUAL_ENTRY(_pthread_join)},	/* PJT_JOIN */
240 	{DUAL_ENTRY(_pthread_key_create)},	/* PJT_KEY_CREATE */
241 	{DUAL_ENTRY(_pthread_key_delete)},	/* PJT_KEY_DELETE*/
242 	{DUAL_ENTRY(_pthread_kill)},	/* PJT_KILL */
243 	{DUAL_ENTRY(_pthread_main_np)},		/* PJT_MAIN_NP */
244 	{DUAL_ENTRY(_pthread_mutexattr_destroy)}, /* PJT_MUTEXATTR_DESTROY */
245 	{DUAL_ENTRY(_pthread_mutexattr_init)},	/* PJT_MUTEXATTR_INIT */
246 	{DUAL_ENTRY(_pthread_mutexattr_settype)}, /* PJT_MUTEXATTR_SETTYPE */
247 	{DUAL_ENTRY(_pthread_mutex_destroy)},	/* PJT_MUTEX_DESTROY */
248 	{DUAL_ENTRY(_pthread_mutex_init)},	/* PJT_MUTEX_INIT */
249 	{(pthread_func_t)__pthread_mutex_lock,
250 	 (pthread_func_t)_pthread_mutex_lock},	/* PJT_MUTEX_LOCK */
251 	{(pthread_func_t)__pthread_mutex_trylock,
252 	 (pthread_func_t)_pthread_mutex_trylock},/* PJT_MUTEX_TRYLOCK */
253 	{DUAL_ENTRY(_pthread_mutex_unlock)},	/* PJT_MUTEX_UNLOCK */
254 	{DUAL_ENTRY(_pthread_once)},		/* PJT_ONCE */
255 	{DUAL_ENTRY(_pthread_rwlock_destroy)},	/* PJT_RWLOCK_DESTROY */
256 	{DUAL_ENTRY(_pthread_rwlock_init)},	/* PJT_RWLOCK_INIT */
257 	{DUAL_ENTRY(_pthread_rwlock_rdlock)},	/* PJT_RWLOCK_RDLOCK */
258 	{DUAL_ENTRY(_pthread_rwlock_tryrdlock)},/* PJT_RWLOCK_TRYRDLOCK */
259 	{DUAL_ENTRY(_pthread_rwlock_trywrlock)},/* PJT_RWLOCK_TRYWRLOCK */
260 	{DUAL_ENTRY(_pthread_rwlock_unlock)},	/* PJT_RWLOCK_UNLOCK */
261 	{DUAL_ENTRY(_pthread_rwlock_wrlock)},	/* PJT_RWLOCK_WRLOCK */
262 	{DUAL_ENTRY(_pthread_self)},		/* PJT_SELF */
263 	{DUAL_ENTRY(_pthread_setcancelstate)},	/* PJT_SETCANCELSTATE */
264 	{DUAL_ENTRY(_pthread_setcanceltype)},	/* PJT_SETCANCELTYPE */
265 	{DUAL_ENTRY(_pthread_setspecific)},	/* PJT_SETSPECIFIC */
266 	{DUAL_ENTRY(_pthread_sigmask)},		/* PJT_SIGMASK */
267 	{DUAL_ENTRY(_pthread_testcancel)},	/* PJT_TESTCANCEL */
268 	{DUAL_ENTRY(__pthread_cleanup_pop_imp)},/* PJT_CLEANUP_POP_IMP */
269 	{DUAL_ENTRY(__pthread_cleanup_push_imp)},/* PJT_CLEANUP_PUSH_IMP */
270 	{DUAL_ENTRY(_pthread_cancel_enter)},	/* PJT_CANCEL_ENTER */
271 	{DUAL_ENTRY(_pthread_cancel_leave)},	/* PJT_CANCEL_LEAVE */
272 	{DUAL_ENTRY(_pthread_mutex_consistent)},/* PJT_MUTEX_CONSISTENT */
273 	{DUAL_ENTRY(_pthread_mutexattr_getrobust)},/* PJT_MUTEXATTR_GETROBUST */
274 	{DUAL_ENTRY(_pthread_mutexattr_setrobust)},/* PJT_MUTEXATTR_SETROBUST */
275 };
276 
277 static int init_once = 0;
278 
279 /*
280  * For the shared version of the threads library, the above is sufficient.
281  * But for the archive version of the library, we need a little bit more.
282  * Namely, we must arrange for this particular module to be pulled in from
283  * the archive library at link time.  To accomplish that, we define and
284  * initialize a variable, "_thread_autoinit_dummy_decl".  This variable is
285  * referenced (as an extern) from libc/stdlib/exit.c. This will always
286  * create a need for this module, ensuring that it is present in the
287  * executable.
288  */
289 extern int _thread_autoinit_dummy_decl;
290 int _thread_autoinit_dummy_decl = 0;
291 
292 void
293 _thread_init_hack(void)
294 {
295 
296 	_libpthread_init(NULL);
297 }
298 
299 
300 /*
301  * Threaded process initialization.
302  *
303  * This is only called under two conditions:
304  *
305  *   1) Some thread routines have detected that the library hasn't yet
306  *      been initialized (_thr_initial == NULL && curthread == NULL), or
307  *
308  *   2) An explicit call to reinitialize after a fork (indicated
309  *      by curthread != NULL)
310  */
311 void
312 _libpthread_init(struct pthread *curthread)
313 {
314 	int first, dlopened;
315 
316 	/* Check if this function has already been called: */
317 	if (_thr_initial != NULL && curthread == NULL)
318 		/* Only initialize the threaded application once. */
319 		return;
320 
321 	/*
322 	 * Check the size of the jump table to make sure it is preset
323 	 * with the correct number of entries.
324 	 */
325 	if (sizeof(jmp_table) != sizeof(pthread_func_t) * PJT_MAX * 2)
326 		PANIC("Thread jump table not properly initialized");
327 	memcpy(__thr_jtable, jmp_table, sizeof(jmp_table));
328 	__thr_interpose_libc();
329 
330 	/* Initialize pthread private data. */
331 	init_private();
332 
333 	/* Set the initial thread. */
334 	if (curthread == NULL) {
335 		first = 1;
336 		/* Create and initialize the initial thread. */
337 		curthread = _thr_alloc(NULL);
338 		if (curthread == NULL)
339 			PANIC("Can't allocate initial thread");
340 		init_main_thread(curthread);
341 	} else {
342 		first = 0;
343 	}
344 
345 	/*
346 	 * Add the thread to the thread list queue.
347 	 */
348 	THR_LIST_ADD(curthread);
349 	_thread_active_threads = 1;
350 
351 	/* Setup the thread specific data */
352 	_tcb_set(curthread->tcb);
353 
354 	if (first) {
355 		_thr_initial = curthread;
356 		dlopened = _rtld_is_dlopened(&_thread_autoinit_dummy_decl) != 0;
357 		_thr_signal_init(dlopened);
358 		if (_thread_event_mask & TD_CREATE)
359 			_thr_report_creation(curthread, curthread);
360 		/*
361 		 * Always use our rtld lock implementation.
362 		 * It is faster because it postpones signal handlers
363 		 * instead of calling sigprocmask(2).
364 		 */
365 		_thr_rtld_init();
366 	}
367 }
368 
369 /*
370  * This function and pthread_create() do a lot of the same things.
371  * It'd be nice to consolidate the common stuff in one place.
372  */
373 static void
374 init_main_thread(struct pthread *thread)
375 {
376 	struct sched_param sched_param;
377 	int i;
378 
379 	/* Setup the thread attributes. */
380 	thr_self(&thread->tid);
381 	thread->attr = _pthread_attr_default;
382 	/*
383 	 * Set up the thread stack.
384 	 *
385 	 * Create a red zone below the main stack.  All other stacks
386 	 * are constrained to a maximum size by the parameters
387 	 * passed to mmap(), but this stack is only limited by
388 	 * resource limits, so this stack needs an explicitly mapped
389 	 * red zone to protect the thread stack that is just beyond.
390 	 */
391 	if (mmap(_usrstack - _thr_stack_initial -
392 	    _thr_guard_default, _thr_guard_default, 0, MAP_ANON,
393 	    -1, 0) == MAP_FAILED)
394 		PANIC("Cannot allocate red zone for initial thread");
395 
396 	/*
397 	 * Mark the stack as an application supplied stack so that it
398 	 * isn't deallocated.
399 	 *
400 	 * XXX - I'm not sure it would hurt anything to deallocate
401 	 *       the main thread stack because deallocation doesn't
402 	 *       actually free() it; it just puts it in the free
403 	 *       stack queue for later reuse.
404 	 */
405 	thread->attr.stackaddr_attr = _usrstack - _thr_stack_initial;
406 	thread->attr.stacksize_attr = _thr_stack_initial;
407 	thread->attr.guardsize_attr = _thr_guard_default;
408 	thread->attr.flags |= THR_STACK_USER;
409 
410 	/*
411 	 * Write a magic value to the thread structure
412 	 * to help identify valid ones:
413 	 */
414 	thread->magic = THR_MAGIC;
415 
416 	thread->cancel_enable = 1;
417 	thread->cancel_async = 0;
418 
419 	/* Initialize the mutex queues */
420 	for (i = 0; i < TMQ_NITEMS; i++)
421 		TAILQ_INIT(&thread->mq[i]);
422 
423 	thread->state = PS_RUNNING;
424 
425 	_thr_getscheduler(thread->tid, &thread->attr.sched_policy,
426 		 &sched_param);
427 	thread->attr.prio = sched_param.sched_priority;
428 
429 #ifdef _PTHREAD_FORCED_UNWIND
430 	thread->unwind_stackend = _usrstack;
431 #endif
432 
433 	/* Others cleared to zero by thr_alloc() */
434 }
435 
436 static void
437 init_private(void)
438 {
439 	struct rlimit rlim;
440 	size_t len;
441 	int mib[2];
442 	char *env, *env_bigstack, *env_splitstack;
443 
444 	_thr_umutex_init(&_mutex_static_lock);
445 	_thr_umutex_init(&_cond_static_lock);
446 	_thr_umutex_init(&_rwlock_static_lock);
447 	_thr_umutex_init(&_keytable_lock);
448 	_thr_urwlock_init(&_thr_atfork_lock);
449 	_thr_umutex_init(&_thr_event_lock);
450 	_thr_umutex_init(&_suspend_all_lock);
451 	_thr_spinlock_init();
452 	_thr_list_init();
453 	_thr_wake_addr_init();
454 	_sleepq_init();
455 	_single_thread = NULL;
456 	_suspend_all_waiters = 0;
457 
458 	/*
459 	 * Avoid reinitializing some things if they don't need to be,
460 	 * e.g. after a fork().
461 	 */
462 	if (init_once == 0) {
463 		__thr_pshared_init();
464 		/* Find the stack top */
465 		mib[0] = CTL_KERN;
466 		mib[1] = KERN_USRSTACK;
467 		len = sizeof (_usrstack);
468 		if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
469 			PANIC("Cannot get kern.usrstack from sysctl");
470 		env_bigstack = getenv("LIBPTHREAD_BIGSTACK_MAIN");
471 		env_splitstack = getenv("LIBPTHREAD_SPLITSTACK_MAIN");
472 		if (env_bigstack != NULL || env_splitstack == NULL) {
473 			if (getrlimit(RLIMIT_STACK, &rlim) == -1)
474 				PANIC("Cannot get stack rlimit");
475 			_thr_stack_initial = rlim.rlim_cur;
476 		}
477 		len = sizeof(_thr_is_smp);
478 		sysctlbyname("kern.smp.cpus", &_thr_is_smp, &len, NULL, 0);
479 		_thr_is_smp = (_thr_is_smp > 1);
480 		_thr_page_size = getpagesize();
481 		_thr_guard_default = _thr_page_size;
482 		_pthread_attr_default.guardsize_attr = _thr_guard_default;
483 		_pthread_attr_default.stacksize_attr = _thr_stack_default;
484 		env = getenv("LIBPTHREAD_SPINLOOPS");
485 		if (env)
486 			_thr_spinloops = atoi(env);
487 		env = getenv("LIBPTHREAD_YIELDLOOPS");
488 		if (env)
489 			_thr_yieldloops = atoi(env);
490 		env = getenv("LIBPTHREAD_QUEUE_FIFO");
491 		if (env)
492 			_thr_queuefifo = atoi(env);
493 		TAILQ_INIT(&_thr_atfork_list);
494 	}
495 	init_once = 1;
496 }
497