xref: /freebsd/lib/libthr/thread/thr_init.c (revision fe6060f10f634930ff71b7c50291ddc610da2475)
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		*_stacktop;
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 	[PJT_ATFORK] = {DUAL_ENTRY(_thr_atfork)},
207 	[PJT_ATTR_DESTROY] = {DUAL_ENTRY(_thr_attr_destroy)},
208 	[PJT_ATTR_GETDETACHSTATE] = {DUAL_ENTRY(_thr_attr_getdetachstate)},
209 	[PJT_ATTR_GETGUARDSIZE] = {DUAL_ENTRY(_thr_attr_getguardsize)},
210 	[PJT_ATTR_GETINHERITSCHED] = {DUAL_ENTRY(_thr_attr_getinheritsched)},
211 	[PJT_ATTR_GETSCHEDPARAM] = {DUAL_ENTRY(_thr_attr_getschedparam)},
212 	[PJT_ATTR_GETSCHEDPOLICY] = {DUAL_ENTRY(_thr_attr_getschedpolicy)},
213 	[PJT_ATTR_GETSCOPE] = {DUAL_ENTRY(_thr_attr_getscope)},
214 	[PJT_ATTR_GETSTACKADDR] = {DUAL_ENTRY(_thr_attr_getstackaddr)},
215 	[PJT_ATTR_GETSTACKSIZE] = {DUAL_ENTRY(_thr_attr_getstacksize)},
216 	[PJT_ATTR_INIT] = {DUAL_ENTRY(_thr_attr_init)},
217 	[PJT_ATTR_SETDETACHSTATE] = {DUAL_ENTRY(_thr_attr_setdetachstate)},
218 	[PJT_ATTR_SETGUARDSIZE] = {DUAL_ENTRY(_thr_attr_setguardsize)},
219 	[PJT_ATTR_SETINHERITSCHED] = {DUAL_ENTRY(_thr_attr_setinheritsched)},
220 	[PJT_ATTR_SETSCHEDPARAM] = {DUAL_ENTRY(_thr_attr_setschedparam)},
221 	[PJT_ATTR_SETSCHEDPOLICY] = {DUAL_ENTRY(_thr_attr_setschedpolicy)},
222 	[PJT_ATTR_SETSCOPE] = {DUAL_ENTRY(_thr_attr_setscope)},
223 	[PJT_ATTR_SETSTACKADDR] = {DUAL_ENTRY(_thr_attr_setstackaddr)},
224 	[PJT_ATTR_SETSTACKSIZE] = {DUAL_ENTRY(_thr_attr_setstacksize)},
225 	[PJT_CANCEL] = {DUAL_ENTRY(_thr_cancel)},
226 	[PJT_CLEANUP_POP] = {DUAL_ENTRY(_thr_cleanup_pop)},
227 	[PJT_CLEANUP_PUSH] = {DUAL_ENTRY(_thr_cleanup_push)},
228 	[PJT_COND_BROADCAST] = {DUAL_ENTRY(_thr_cond_broadcast)},
229 	[PJT_COND_DESTROY] = {DUAL_ENTRY(_thr_cond_destroy)},
230 	[PJT_COND_INIT] = {DUAL_ENTRY(_thr_cond_init)},
231 	[PJT_COND_SIGNAL] = {DUAL_ENTRY(_thr_cond_signal)},
232 	[PJT_COND_TIMEDWAIT] = {DUAL_ENTRY(_thr_cond_timedwait)},
233 	[PJT_COND_WAIT] = {(pthread_func_t)__thr_cond_wait,
234 	    (pthread_func_t)_thr_cond_wait},
235 	[PJT_DETACH] = {DUAL_ENTRY(_thr_detach)},
236 	[PJT_EQUAL] = {DUAL_ENTRY(_thr_equal)},
237 	[PJT_EXIT] = {DUAL_ENTRY(_Tthr_exit)},
238 	[PJT_GETSPECIFIC] = {DUAL_ENTRY(_thr_getspecific)},
239 	[PJT_JOIN] = {DUAL_ENTRY(_thr_join)},
240 	[PJT_KEY_CREATE] = {DUAL_ENTRY(_thr_key_create)},
241 	[PJT_KEY_DELETE] = {DUAL_ENTRY(_thr_key_delete)},
242 	[PJT_KILL] = {DUAL_ENTRY(_Tthr_kill)},
243 	[PJT_MAIN_NP] = {DUAL_ENTRY(_thr_main_np)},
244 	[PJT_MUTEXATTR_DESTROY] = {DUAL_ENTRY(_thr_mutexattr_destroy)},
245 	[PJT_MUTEXATTR_INIT] = {DUAL_ENTRY(_thr_mutexattr_init)},
246 	[PJT_MUTEXATTR_SETTYPE] = {DUAL_ENTRY(_thr_mutexattr_settype)},
247 	[PJT_MUTEX_DESTROY] = {DUAL_ENTRY(_thr_mutex_destroy)},
248 	[PJT_MUTEX_INIT] = {DUAL_ENTRY(__Tthr_mutex_init)},
249 	[PJT_MUTEX_LOCK] = {DUAL_ENTRY(__Tthr_mutex_lock)},
250 	[PJT_MUTEX_TRYLOCK] = {DUAL_ENTRY(__Tthr_mutex_trylock)},
251 	[PJT_MUTEX_UNLOCK] = {DUAL_ENTRY(_thr_mutex_unlock)},
252 	[PJT_ONCE] = {DUAL_ENTRY(_thr_once)},
253 	[PJT_RWLOCK_DESTROY] = {DUAL_ENTRY(_thr_rwlock_destroy)},
254 	[PJT_RWLOCK_INIT] = {DUAL_ENTRY(_thr_rwlock_init)},
255 	[PJT_RWLOCK_RDLOCK] = {DUAL_ENTRY(_Tthr_rwlock_rdlock)},
256 	[PJT_RWLOCK_TRYRDLOCK] = {DUAL_ENTRY(_Tthr_rwlock_tryrdlock)},
257 	[PJT_RWLOCK_TRYWRLOCK] = {DUAL_ENTRY(_Tthr_rwlock_trywrlock)},
258 	[PJT_RWLOCK_UNLOCK] = {DUAL_ENTRY(_Tthr_rwlock_unlock)},
259 	[PJT_RWLOCK_WRLOCK] = {DUAL_ENTRY(_Tthr_rwlock_wrlock)},
260 	[PJT_SELF] = {DUAL_ENTRY(_Tthr_self)},
261 	[PJT_SETCANCELSTATE] = {DUAL_ENTRY(_thr_setcancelstate)},
262 	[PJT_SETCANCELTYPE] = {DUAL_ENTRY(_thr_setcanceltype)},
263 	[PJT_SETSPECIFIC] = {DUAL_ENTRY(_thr_setspecific)},
264 	[PJT_SIGMASK] = {DUAL_ENTRY(_thr_sigmask)},
265 	[PJT_TESTCANCEL] = {DUAL_ENTRY(_Tthr_testcancel)},
266 	[PJT_CLEANUP_POP_IMP] = {DUAL_ENTRY(__thr_cleanup_pop_imp)},
267 	[PJT_CLEANUP_PUSH_IMP] = {DUAL_ENTRY(__thr_cleanup_push_imp)},
268 	[PJT_CANCEL_ENTER] = {DUAL_ENTRY(_Tthr_cancel_enter)},
269 	[PJT_CANCEL_LEAVE] = {DUAL_ENTRY(_Tthr_cancel_leave)},
270 	[PJT_MUTEX_CONSISTENT] = {DUAL_ENTRY(_Tthr_mutex_consistent)},
271 	[PJT_MUTEXATTR_GETROBUST] = {DUAL_ENTRY(_thr_mutexattr_getrobust)},
272 	[PJT_MUTEXATTR_SETROBUST] = {DUAL_ENTRY(_thr_mutexattr_setrobust)},
273 	[PJT_GETTHREADID_NP] = {DUAL_ENTRY(_thr_getthreadid_np)},
274 	[PJT_ATTR_GET_NP] = {DUAL_ENTRY(_thr_attr_get_np)},
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(_stacktop - _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 = _stacktop - _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 = _stacktop;
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 		__thr_malloc_init();
465 		/* Find the stack top */
466 		mib[0] = CTL_KERN;
467 		mib[1] = KERN_STACKTOP;
468 		len = sizeof (_stacktop);
469 		if (sysctl(mib, 2, &_stacktop, &len, NULL, 0) == -1) {
470 			mib[1] = KERN_USRSTACK;
471 			if (sysctl(mib, 2, &_stacktop, &len, NULL, 0) == -1)
472 				PANIC("Cannot get kern.usrstack from sysctl");
473 		}
474 		env_bigstack = getenv("LIBPTHREAD_BIGSTACK_MAIN");
475 		env_splitstack = getenv("LIBPTHREAD_SPLITSTACK_MAIN");
476 		if (env_bigstack != NULL || env_splitstack == NULL) {
477 			if (getrlimit(RLIMIT_STACK, &rlim) == -1)
478 				PANIC("Cannot get stack rlimit");
479 			_thr_stack_initial = rlim.rlim_cur;
480 		}
481 		_thr_is_smp = sysconf(_SC_NPROCESSORS_CONF);
482 		if (_thr_is_smp == -1)
483 			PANIC("Cannot get _SC_NPROCESSORS_CONF");
484 		_thr_is_smp = (_thr_is_smp > 1);
485 		_thr_page_size = getpagesize();
486 		_thr_guard_default = _thr_page_size;
487 		_pthread_attr_default.guardsize_attr = _thr_guard_default;
488 		_pthread_attr_default.stacksize_attr = _thr_stack_default;
489 		env = getenv("LIBPTHREAD_SPINLOOPS");
490 		if (env)
491 			_thr_spinloops = atoi(env);
492 		env = getenv("LIBPTHREAD_YIELDLOOPS");
493 		if (env)
494 			_thr_yieldloops = atoi(env);
495 		env = getenv("LIBPTHREAD_QUEUE_FIFO");
496 		if (env)
497 			_thr_queuefifo = atoi(env);
498 		TAILQ_INIT(&_thr_atfork_list);
499 	}
500 	init_once = 1;
501 }
502