xref: /freebsd/lib/libthr/thread/thr_init.c (revision 6607310b740c499e273ae5bbf1f308ed91b61c05)
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/sysctl.h>
41 #include <sys/ttycom.h>
42 #include <sys/mman.h>
43 #include <sys/rtprio.h>
44 #include <errno.h>
45 #include <fcntl.h>
46 #include <paths.h>
47 #include <pthread.h>
48 #include <pthread_np.h>
49 #include <signal.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <time.h>
53 #include <unistd.h>
54 #include "un-namespace.h"
55 
56 #include "libc_private.h"
57 #include "thr_private.h"
58 
59 char		*_usrstack;
60 struct pthread	*_thr_initial;
61 int		_libthr_debug;
62 int		_thread_event_mask;
63 struct pthread	*_thread_last_event;
64 pthreadlist	_thread_list = TAILQ_HEAD_INITIALIZER(_thread_list);
65 pthreadlist 	_thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
66 int		_thread_active_threads = 1;
67 atfork_head	_thr_atfork_list = TAILQ_HEAD_INITIALIZER(_thr_atfork_list);
68 struct umutex	_thr_atfork_lock = DEFAULT_UMUTEX;
69 
70 struct pthread_prio	_thr_priorities[3] = {
71 	{RTP_PRIO_MIN,  RTP_PRIO_MAX, 0}, /* FIFO */
72 	{0, 0, 63}, /* OTHER */
73 	{RTP_PRIO_MIN, RTP_PRIO_MAX, 0}  /* RR */
74 };
75 
76 struct pthread_attr _pthread_attr_default = {
77 	.sched_policy = SCHED_OTHER,
78 	.sched_inherit = 0,
79 	.prio = 0,
80 	.suspend = THR_CREATE_RUNNING,
81 	.flags = PTHREAD_SCOPE_SYSTEM,
82 	.stackaddr_attr = NULL,
83 	.stacksize_attr = THR_STACK_DEFAULT,
84 	.guardsize_attr = 0
85 };
86 
87 struct pthread_mutex_attr _pthread_mutexattr_default = {
88 	.m_type = PTHREAD_MUTEX_DEFAULT,
89 	.m_protocol = PTHREAD_PRIO_NONE,
90 	.m_ceiling = 0,
91 	.m_flags = 0
92 };
93 
94 /* Default condition variable attributes: */
95 struct pthread_cond_attr _pthread_condattr_default = {
96 	.c_pshared = PTHREAD_PROCESS_PRIVATE,
97 	.c_clockid = CLOCK_REALTIME
98 };
99 
100 pid_t		_thr_pid;
101 int		_thr_is_smp = 0;
102 size_t		_thr_guard_default;
103 size_t		_thr_stack_default = THR_STACK_DEFAULT;
104 size_t		_thr_stack_initial = THR_STACK_INITIAL;
105 int		_thr_page_size;
106 int		_thr_spinloops;
107 int		_thr_yieldloops;
108 int		_gc_count;
109 struct umutex	_mutex_static_lock = DEFAULT_UMUTEX;
110 struct umutex	_cond_static_lock = DEFAULT_UMUTEX;
111 struct umutex	_rwlock_static_lock = DEFAULT_UMUTEX;
112 struct umutex	_keytable_lock = DEFAULT_UMUTEX;
113 struct umutex	_thr_list_lock = DEFAULT_UMUTEX;
114 struct umutex	_thr_event_lock = DEFAULT_UMUTEX;
115 
116 int	__pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
117 int	__pthread_mutex_lock(pthread_mutex_t *);
118 int	__pthread_mutex_trylock(pthread_mutex_t *);
119 void	_thread_init_hack(void) __attribute__ ((constructor));
120 
121 static void init_private(void);
122 static void init_main_thread(struct pthread *thread);
123 
124 /*
125  * All weak references used within libc should be in this table.
126  * This is so that static libraries will work.
127  */
128 
129 STATIC_LIB_REQUIRE(_fork);
130 STATIC_LIB_REQUIRE(_pthread_getspecific);
131 STATIC_LIB_REQUIRE(_pthread_key_create);
132 STATIC_LIB_REQUIRE(_pthread_key_delete);
133 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
134 STATIC_LIB_REQUIRE(_pthread_mutex_init);
135 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
136 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
137 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
138 STATIC_LIB_REQUIRE(_pthread_mutexattr_init);
139 STATIC_LIB_REQUIRE(_pthread_mutexattr_destroy);
140 STATIC_LIB_REQUIRE(_pthread_mutexattr_settype);
141 STATIC_LIB_REQUIRE(_pthread_once);
142 STATIC_LIB_REQUIRE(_pthread_setspecific);
143 STATIC_LIB_REQUIRE(_raise);
144 STATIC_LIB_REQUIRE(_sem_destroy);
145 STATIC_LIB_REQUIRE(_sem_getvalue);
146 STATIC_LIB_REQUIRE(_sem_init);
147 STATIC_LIB_REQUIRE(_sem_post);
148 STATIC_LIB_REQUIRE(_sem_timedwait);
149 STATIC_LIB_REQUIRE(_sem_trywait);
150 STATIC_LIB_REQUIRE(_sem_wait);
151 STATIC_LIB_REQUIRE(_sigaction);
152 STATIC_LIB_REQUIRE(_sigprocmask);
153 STATIC_LIB_REQUIRE(_sigsuspend);
154 STATIC_LIB_REQUIRE(_sigtimedwait);
155 STATIC_LIB_REQUIRE(_sigwait);
156 STATIC_LIB_REQUIRE(_sigwaitinfo);
157 STATIC_LIB_REQUIRE(_spinlock);
158 STATIC_LIB_REQUIRE(_spinlock_debug);
159 STATIC_LIB_REQUIRE(_spinunlock);
160 STATIC_LIB_REQUIRE(_thread_init_hack);
161 STATIC_LIB_REQUIRE(_vfork);
162 
163 /*
164  * These are needed when linking statically.  All references within
165  * libgcc (and in the future libc) to these routines are weak, but
166  * if they are not (strongly) referenced by the application or other
167  * libraries, then the actual functions will not be loaded.
168  */
169 STATIC_LIB_REQUIRE(_pthread_once);
170 STATIC_LIB_REQUIRE(_pthread_key_create);
171 STATIC_LIB_REQUIRE(_pthread_key_delete);
172 STATIC_LIB_REQUIRE(_pthread_getspecific);
173 STATIC_LIB_REQUIRE(_pthread_setspecific);
174 STATIC_LIB_REQUIRE(_pthread_mutex_init);
175 STATIC_LIB_REQUIRE(_pthread_mutex_destroy);
176 STATIC_LIB_REQUIRE(_pthread_mutex_lock);
177 STATIC_LIB_REQUIRE(_pthread_mutex_trylock);
178 STATIC_LIB_REQUIRE(_pthread_mutex_unlock);
179 STATIC_LIB_REQUIRE(_pthread_create);
180 
181 /* Pull in all symbols required by libthread_db */
182 STATIC_LIB_REQUIRE(_thread_state_running);
183 
184 #define	DUAL_ENTRY(entry)	\
185 	(pthread_func_t)entry, (pthread_func_t)entry
186 
187 static pthread_func_t jmp_table[][2] = {
188 	{DUAL_ENTRY(_pthread_atfork)},	/* PJT_ATFORK */
189 	{DUAL_ENTRY(_pthread_attr_destroy)},	/* PJT_ATTR_DESTROY */
190 	{DUAL_ENTRY(_pthread_attr_getdetachstate)},	/* PJT_ATTR_GETDETACHSTATE */
191 	{DUAL_ENTRY(_pthread_attr_getguardsize)},	/* PJT_ATTR_GETGUARDSIZE */
192 	{DUAL_ENTRY(_pthread_attr_getinheritsched)},	/* PJT_ATTR_GETINHERITSCHED */
193 	{DUAL_ENTRY(_pthread_attr_getschedparam)},	/* PJT_ATTR_GETSCHEDPARAM */
194 	{DUAL_ENTRY(_pthread_attr_getschedpolicy)},	/* PJT_ATTR_GETSCHEDPOLICY */
195 	{DUAL_ENTRY(_pthread_attr_getscope)},	/* PJT_ATTR_GETSCOPE */
196 	{DUAL_ENTRY(_pthread_attr_getstackaddr)},	/* PJT_ATTR_GETSTACKADDR */
197 	{DUAL_ENTRY(_pthread_attr_getstacksize)},	/* PJT_ATTR_GETSTACKSIZE */
198 	{DUAL_ENTRY(_pthread_attr_init)},	/* PJT_ATTR_INIT */
199 	{DUAL_ENTRY(_pthread_attr_setdetachstate)},	/* PJT_ATTR_SETDETACHSTATE */
200 	{DUAL_ENTRY(_pthread_attr_setguardsize)},	/* PJT_ATTR_SETGUARDSIZE */
201 	{DUAL_ENTRY(_pthread_attr_setinheritsched)},	/* PJT_ATTR_SETINHERITSCHED */
202 	{DUAL_ENTRY(_pthread_attr_setschedparam)},	/* PJT_ATTR_SETSCHEDPARAM */
203 	{DUAL_ENTRY(_pthread_attr_setschedpolicy)},	/* PJT_ATTR_SETSCHEDPOLICY */
204 	{DUAL_ENTRY(_pthread_attr_setscope)},	/* PJT_ATTR_SETSCOPE */
205 	{DUAL_ENTRY(_pthread_attr_setstackaddr)},	/* PJT_ATTR_SETSTACKADDR */
206 	{DUAL_ENTRY(_pthread_attr_setstacksize)},	/* PJT_ATTR_SETSTACKSIZE */
207 	{DUAL_ENTRY(_pthread_cancel)},	/* PJT_CANCEL */
208 	{DUAL_ENTRY(_pthread_cleanup_pop)},	/* PJT_CLEANUP_POP */
209 	{DUAL_ENTRY(_pthread_cleanup_push)},	/* PJT_CLEANUP_PUSH */
210 	{DUAL_ENTRY(_pthread_cond_broadcast)},	/* PJT_COND_BROADCAST */
211 	{DUAL_ENTRY(_pthread_cond_destroy)},	/* PJT_COND_DESTROY */
212 	{DUAL_ENTRY(_pthread_cond_init)},	/* PJT_COND_INIT */
213 	{DUAL_ENTRY(_pthread_cond_signal)},	/* PJT_COND_SIGNAL */
214 	{DUAL_ENTRY(_pthread_cond_timedwait)},	/* PJT_COND_TIMEDWAIT */
215 	{(pthread_func_t)__pthread_cond_wait,
216 	 (pthread_func_t)_pthread_cond_wait},	/* PJT_COND_WAIT */
217 	{DUAL_ENTRY(_pthread_detach)},	/* PJT_DETACH */
218 	{DUAL_ENTRY(_pthread_equal)},	/* PJT_EQUAL */
219 	{DUAL_ENTRY(_pthread_exit)},	/* PJT_EXIT */
220 	{DUAL_ENTRY(_pthread_getspecific)},	/* PJT_GETSPECIFIC */
221 	{DUAL_ENTRY(_pthread_join)},	/* PJT_JOIN */
222 	{DUAL_ENTRY(_pthread_key_create)},	/* PJT_KEY_CREATE */
223 	{DUAL_ENTRY(_pthread_key_delete)},	/* PJT_KEY_DELETE*/
224 	{DUAL_ENTRY(_pthread_kill)},	/* PJT_KILL */
225 	{DUAL_ENTRY(_pthread_main_np)},		/* PJT_MAIN_NP */
226 	{DUAL_ENTRY(_pthread_mutexattr_destroy)}, /* PJT_MUTEXATTR_DESTROY */
227 	{DUAL_ENTRY(_pthread_mutexattr_init)},	/* PJT_MUTEXATTR_INIT */
228 	{DUAL_ENTRY(_pthread_mutexattr_settype)}, /* PJT_MUTEXATTR_SETTYPE */
229 	{DUAL_ENTRY(_pthread_mutex_destroy)},	/* PJT_MUTEX_DESTROY */
230 	{DUAL_ENTRY(_pthread_mutex_init)},	/* PJT_MUTEX_INIT */
231 	{(pthread_func_t)__pthread_mutex_lock,
232 	 (pthread_func_t)_pthread_mutex_lock},	/* PJT_MUTEX_LOCK */
233 	{(pthread_func_t)__pthread_mutex_trylock,
234 	 (pthread_func_t)_pthread_mutex_trylock},/* PJT_MUTEX_TRYLOCK */
235 	{DUAL_ENTRY(_pthread_mutex_unlock)},	/* PJT_MUTEX_UNLOCK */
236 	{DUAL_ENTRY(_pthread_once)},		/* PJT_ONCE */
237 	{DUAL_ENTRY(_pthread_rwlock_destroy)},	/* PJT_RWLOCK_DESTROY */
238 	{DUAL_ENTRY(_pthread_rwlock_init)},	/* PJT_RWLOCK_INIT */
239 	{DUAL_ENTRY(_pthread_rwlock_rdlock)},	/* PJT_RWLOCK_RDLOCK */
240 	{DUAL_ENTRY(_pthread_rwlock_tryrdlock)},/* PJT_RWLOCK_TRYRDLOCK */
241 	{DUAL_ENTRY(_pthread_rwlock_trywrlock)},/* PJT_RWLOCK_TRYWRLOCK */
242 	{DUAL_ENTRY(_pthread_rwlock_unlock)},	/* PJT_RWLOCK_UNLOCK */
243 	{DUAL_ENTRY(_pthread_rwlock_wrlock)},	/* PJT_RWLOCK_WRLOCK */
244 	{DUAL_ENTRY(_pthread_self)},		/* PJT_SELF */
245 	{DUAL_ENTRY(_pthread_setcancelstate)},	/* PJT_SETCANCELSTATE */
246 	{DUAL_ENTRY(_pthread_setcanceltype)},	/* PJT_SETCANCELTYPE */
247 	{DUAL_ENTRY(_pthread_setspecific)},	/* PJT_SETSPECIFIC */
248 	{DUAL_ENTRY(_pthread_sigmask)},		/* PJT_SIGMASK */
249 	{DUAL_ENTRY(_pthread_testcancel)}	/* PJT_TESTCANCEL */
250 };
251 
252 static int init_once = 0;
253 
254 /*
255  * For the shared version of the threads library, the above is sufficient.
256  * But for the archive version of the library, we need a little bit more.
257  * Namely, we must arrange for this particular module to be pulled in from
258  * the archive library at link time.  To accomplish that, we define and
259  * initialize a variable, "_thread_autoinit_dummy_decl".  This variable is
260  * referenced (as an extern) from libc/stdlib/exit.c. This will always
261  * create a need for this module, ensuring that it is present in the
262  * executable.
263  */
264 extern int _thread_autoinit_dummy_decl;
265 int _thread_autoinit_dummy_decl = 0;
266 
267 void
268 _thread_init_hack(void)
269 {
270 
271 	_libpthread_init(NULL);
272 }
273 
274 
275 /*
276  * Threaded process initialization.
277  *
278  * This is only called under two conditions:
279  *
280  *   1) Some thread routines have detected that the library hasn't yet
281  *      been initialized (_thr_initial == NULL && curthread == NULL), or
282  *
283  *   2) An explicit call to reinitialize after a fork (indicated
284  *      by curthread != NULL)
285  */
286 void
287 _libpthread_init(struct pthread *curthread)
288 {
289 	int fd, first = 0;
290 	sigset_t sigset, oldset;
291 
292 	/* Check if this function has already been called: */
293 	if ((_thr_initial != NULL) && (curthread == NULL))
294 		/* Only initialize the threaded application once. */
295 		return;
296 
297 	/*
298 	 * Check the size of the jump table to make sure it is preset
299 	 * with the correct number of entries.
300 	 */
301 	if (sizeof(jmp_table) != (sizeof(pthread_func_t) * PJT_MAX * 2))
302 		PANIC("Thread jump table not properly initialized");
303 	memcpy(__thr_jtable, jmp_table, sizeof(jmp_table));
304 
305 	/*
306 	 * Check for the special case of this process running as
307 	 * or in place of init as pid = 1:
308 	 */
309 	if ((_thr_pid = getpid()) == 1) {
310 		/*
311 		 * Setup a new session for this process which is
312 		 * assumed to be running as root.
313 		 */
314 		if (setsid() == -1)
315 			PANIC("Can't set session ID");
316 		if (revoke(_PATH_CONSOLE) != 0)
317 			PANIC("Can't revoke console");
318 		if ((fd = __sys_open(_PATH_CONSOLE, O_RDWR)) < 0)
319 			PANIC("Can't open console");
320 		if (setlogin("root") == -1)
321 			PANIC("Can't set login to root");
322 		if (_ioctl(fd, TIOCSCTTY, (char *) NULL) == -1)
323 			PANIC("Can't set controlling terminal");
324 	}
325 
326 	/* Initialize pthread private data. */
327 	init_private();
328 
329 	/* Set the initial thread. */
330 	if (curthread == NULL) {
331 		first = 1;
332 		/* Create and initialize the initial thread. */
333 		curthread = _thr_alloc(NULL);
334 		if (curthread == NULL)
335 			PANIC("Can't allocate initial thread");
336 		init_main_thread(curthread);
337 	}
338 	/*
339 	 * Add the thread to the thread list queue.
340 	 */
341 	THR_LIST_ADD(curthread);
342 	_thread_active_threads = 1;
343 
344 	/* Setup the thread specific data */
345 	_tcb_set(curthread->tcb);
346 
347 	if (first) {
348 		SIGFILLSET(sigset);
349 		SIGDELSET(sigset, SIGTRAP);
350 		__sys_sigprocmask(SIG_SETMASK, &sigset, &oldset);
351 		_thr_signal_init();
352 		_thr_initial = curthread;
353 		SIGDELSET(oldset, SIGCANCEL);
354 		__sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
355 		if (_thread_event_mask & TD_CREATE)
356 			_thr_report_creation(curthread, curthread);
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 	thr_set_name(thread->tid, "initial thread");
409 
410 	/* Initialize the mutex queue: */
411 	TAILQ_INIT(&thread->mutexq);
412 	TAILQ_INIT(&thread->pp_mutexq);
413 
414 	thread->state = PS_RUNNING;
415 
416 	_thr_getscheduler(thread->tid, &thread->attr.sched_policy,
417 		 &sched_param);
418 	thread->attr.prio = sched_param.sched_priority;
419 
420 	/* Others cleared to zero by thr_alloc() */
421 }
422 
423 static void
424 init_private(void)
425 {
426 	size_t len;
427 	int mib[2];
428 	char *env;
429 
430 	_thr_umutex_init(&_mutex_static_lock);
431 	_thr_umutex_init(&_cond_static_lock);
432 	_thr_umutex_init(&_rwlock_static_lock);
433 	_thr_umutex_init(&_keytable_lock);
434 	_thr_umutex_init(&_thr_atfork_lock);
435 	_thr_umutex_init(&_thr_event_lock);
436 	_thr_once_init();
437 	_thr_spinlock_init();
438 	_thr_list_init();
439 
440 	/*
441 	 * Avoid reinitializing some things if they don't need to be,
442 	 * e.g. after a fork().
443 	 */
444 	if (init_once == 0) {
445 		/* Find the stack top */
446 		mib[0] = CTL_KERN;
447 		mib[1] = KERN_USRSTACK;
448 		len = sizeof (_usrstack);
449 		if (sysctl(mib, 2, &_usrstack, &len, NULL, 0) == -1)
450 			PANIC("Cannot get kern.usrstack from sysctl");
451 		len = sizeof(_thr_is_smp);
452 		sysctlbyname("kern.smp.cpus", &_thr_is_smp, &len, NULL, 0);
453 		_thr_is_smp = (_thr_is_smp > 1);
454 		_thr_page_size = getpagesize();
455 		_thr_guard_default = _thr_page_size;
456 		_pthread_attr_default.guardsize_attr = _thr_guard_default;
457 		_pthread_attr_default.stacksize_attr = _thr_stack_default;
458 		env = getenv("LIBPTHREAD_SPINLOOPS");
459 		if (env)
460 			_thr_spinloops = atoi(env);
461 		env = getenv("LIBPTHREAD_YIELDLOOPS");
462 		if (env)
463 			_thr_yieldloops = atoi(env);
464 		TAILQ_INIT(&_thr_atfork_list);
465 	}
466 	init_once = 1;
467 }
468