NetBSD/lib/libpthread/pthread.c

/*	$NetBSD: pthread.c,v 1.96 2008/01/08 20:56:08 christos Exp $	*/

/*-
 * Copyright (c) 2001, 2002, 2003, 2006, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nathan J. Williams and Andrew Doran.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *        This product includes software developed by the NetBSD
 *        Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: pthread.c,v 1.96 2008/01/08 20:56:08 christos Exp $");

#define	__EXPOSE_STACK	1

#include <sys/param.h>
#include <sys/mman.h>
#include <sys/sysctl.h>
#include <sys/lwpctl.h>

#include <err.h>
#include <errno.h>
#include <lwp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <ucontext.h>
#include <unistd.h>
#include <sched.h>

#include "pthread.h"
#include "pthread_int.h"

pthread_rwlock_t pthread__alltree_lock = PTHREAD_RWLOCK_INITIALIZER;
RB_HEAD(__pthread__alltree, __pthread_st) pthread__alltree;

#ifndef lint
static int	pthread__cmp(struct __pthread_st *, struct __pthread_st *);
RB_PROTOTYPE_STATIC(__pthread__alltree, __pthread_st, pt_alltree, pthread__cmp)
#endif

static void	pthread__create_tramp(pthread_t, void *(*)(void *), void *);
static void	pthread__initthread(pthread_t);
static void	pthread__scrubthread(pthread_t, char *, int);
static int	pthread__stackid_setup(void *, size_t, pthread_t *);
static int	pthread__stackalloc(pthread_t *);
static void	pthread__initmain(pthread_t *);
static void	pthread__fork_callback(void);
static void	pthread__reap(pthread_t);
static void	pthread__child_callback(void);
static void	pthread__start(void);

void	pthread__init(void);

int pthread__started;
pthread_mutex_t pthread__deadqueue_lock = PTHREAD_MUTEX_INITIALIZER;
pthread_queue_t pthread__deadqueue;
pthread_queue_t pthread__allqueue;

static pthread_attr_t pthread_default_attr;
static lwpctl_t pthread__dummy_lwpctl = { .lc_curcpu = LWPCTL_CPU_NONE };
static pthread_t pthread__first;

enum {
	DIAGASSERT_ABORT =	1<<0,
	DIAGASSERT_STDERR =	1<<1,
	DIAGASSERT_SYSLOG =	1<<2
};

static int pthread__diagassert = DIAGASSERT_ABORT | DIAGASSERT_STDERR;

int pthread__concurrency;
int pthread__nspins;
int pthread__unpark_max = PTHREAD__UNPARK_MAX;
int pthread__osrev;

/* 
 * We have to initialize the pthread_stack* variables here because
 * mutexes are used before pthread_init() and thus pthread__initmain()
 * are called.  Since mutexes only save the stack pointer and not a
 * pointer to the thread data, it is safe to change the mapping from
 * stack pointer to thread data afterwards.
 */
#define	_STACKSIZE_LG 18
int	pthread__stacksize_lg = _STACKSIZE_LG;
size_t	pthread__stacksize = 1 << _STACKSIZE_LG;
vaddr_t	pthread__stackmask = (1 << _STACKSIZE_LG) - 1;
vaddr_t pthread__threadmask = (vaddr_t)~((1 << _STACKSIZE_LG) - 1);
#undef	_STACKSIZE_LG

int _sys___sigprocmask14(int, const sigset_t *, sigset_t *);

__strong_alias(__libc_thr_self,pthread_self)
__strong_alias(__libc_thr_create,pthread_create)
__strong_alias(__libc_thr_exit,pthread_exit)
__strong_alias(__libc_thr_errno,pthread__errno)
__strong_alias(__libc_thr_setcancelstate,pthread_setcancelstate)
__strong_alias(__libc_thr_equal,pthread_equal)
__strong_alias(__libc_thr_init,pthread__init)

/*
 * Static library kludge.  Place a reference to a symbol any library
 * file which does not already have a reference here.
 */
extern int pthread__cancel_stub_binder;

void *pthread__static_lib_binder[] = {
	&pthread__cancel_stub_binder,
	pthread_cond_init,
	pthread_mutex_init,
	pthread_rwlock_init,
	pthread_barrier_init,
	pthread_key_create,
	pthread_setspecific,
};

/*
 * This needs to be started by the library loading code, before main()
 * gets to run, for various things that use the state of the initial thread
 * to work properly (thread-specific data is an application-visible example;
 * spinlock counts for mutexes is an internal example).
 */
void
pthread__init(void)
{
	pthread_t first;
	char *p;
	int i, mib[2];
	size_t len;
	extern int __isthreaded;

	mib[0] = CTL_HW;
	mib[1] = HW_NCPU; 

	len = sizeof(pthread__concurrency);
	if (sysctl(mib, 2, &pthread__concurrency, &len, NULL, 0) == -1)
		err(1, "sysctl(hw.ncpu");

	mib[0] = CTL_KERN;
	mib[1] = KERN_OSREV; 

	len = sizeof(pthread__osrev);
	if (sysctl(mib, 2, &pthread__osrev, &len, NULL, 0) == -1)
		err(1, "sysctl(hw.osrevision");

	/* Initialize locks first; they're needed elsewhere. */
	pthread__lockprim_init();

	/* Fetch parameters. */
	i = (int)_lwp_unpark_all(NULL, 0, NULL);
	if (i == -1)
		err(1, "_lwp_unpark_all");
	if (i < pthread__unpark_max)
		pthread__unpark_max = i;

	/* Basic data structure setup */
	pthread_attr_init(&pthread_default_attr);
	PTQ_INIT(&pthread__allqueue);
	PTQ_INIT(&pthread__deadqueue);
	RB_INIT(&pthread__alltree);

	/* Create the thread structure corresponding to main() */
	pthread__initmain(&first);
	pthread__initthread(first);
	pthread__scrubthread(first, NULL, 0);

	first->pt_lid = _lwp_self();
	PTQ_INSERT_HEAD(&pthread__allqueue, first, pt_allq);
	RB_INSERT(__pthread__alltree, &pthread__alltree, first);

	(void)_lwp_ctl(LWPCTL_FEATURE_CURCPU, &first->pt_lwpctl);

	/* Start subsystems */
	PTHREAD_MD_INIT

	for (p = pthread__getenv("PTHREAD_DIAGASSERT"); p && *p; p++) {
		switch (*p) {
		case 'a':
			pthread__diagassert |= DIAGASSERT_ABORT;
			break;
		case 'A':
			pthread__diagassert &= ~DIAGASSERT_ABORT;
			break;
		case 'e':
			pthread__diagassert |= DIAGASSERT_STDERR;
			break;
		case 'E':
			pthread__diagassert &= ~DIAGASSERT_STDERR;
			break;
		case 'l':
			pthread__diagassert |= DIAGASSERT_SYSLOG;
			break;
		case 'L':
			pthread__diagassert &= ~DIAGASSERT_SYSLOG;
			break;
		}
	}

	/* Tell libc that we're here and it should role-play accordingly. */
	pthread__first = first;
	pthread_atfork(NULL, NULL, pthread__fork_callback);
	__isthreaded = 1;
}

static void
pthread__fork_callback(void)
{

	/* lwpctl state is not copied across fork. */
	(void)_lwp_ctl(LWPCTL_FEATURE_CURCPU, &pthread__first->pt_lwpctl);
}

static void
pthread__child_callback(void)
{

	/*
	 * Clean up data structures that a forked child process might
	 * trip over. Note that if threads have been created (causing
	 * this handler to be registered) the standards say that the
	 * child will trigger undefined behavior if it makes any
	 * pthread_* calls (or any other calls that aren't
	 * async-signal-safe), so we don't really have to clean up
	 * much. Anything that permits some pthread_* calls to work is
	 * merely being polite.
	 */
	pthread__started = 0;
}

static void
pthread__start(void)
{

	/*
	 * Per-process timers are cleared by fork(); despite the
	 * various restrictions on fork() and threads, it's legal to
	 * fork() before creating any threads. 
	 */
	pthread_atfork(NULL, NULL, pthread__child_callback);
}


/* General-purpose thread data structure sanitization. */
/* ARGSUSED */
static void
pthread__initthread(pthread_t t)
{

	t->pt_self = t;
	t->pt_magic = PT_MAGIC;
	t->pt_willpark = 0;
	t->pt_unpark = 0;
	t->pt_sleeponq = 0;
	t->pt_nwaiters = 0;
	t->pt_sleepobj = NULL;
	t->pt_signalled = 0;
	t->pt_havespecific = 0;
	t->pt_early = NULL;
	t->pt_lwpctl = &pthread__dummy_lwpctl;
	t->pt_blocking = 0;
	t->pt_droplock = NULL;

	memcpy(&t->pt_lockops, pthread__lock_ops, sizeof(t->pt_lockops));
	pthread_mutex_init(&t->pt_lock, NULL);
	PTQ_INIT(&t->pt_cleanup_stack);
	pthread_cond_init(&t->pt_joiners, NULL);
	memset(&t->pt_specific, 0, sizeof(t->pt_specific));
}

static void
pthread__scrubthread(pthread_t t, char *name, int flags)
{

	t->pt_state = PT_STATE_RUNNING;
	t->pt_exitval = NULL;
	t->pt_flags = flags;
	t->pt_cancel = 0;
	t->pt_errno = 0;
	t->pt_name = name;
	t->pt_lid = 0;
}


int
pthread_create(pthread_t *thread, const pthread_attr_t *attr,
	    void *(*startfunc)(void *), void *arg)
{
	pthread_t newthread;
	pthread_attr_t nattr;
	struct pthread_attr_private *p;
	char * volatile name;
	unsigned long flag;
	int ret;

	/*
	 * It's okay to check this without a lock because there can
	 * only be one thread before it becomes true.
	 */
	if (pthread__started == 0) {
		pthread__start();
		pthread__started = 1;
	}

	if (attr == NULL)
		nattr = pthread_default_attr;
	else if (attr->pta_magic == PT_ATTR_MAGIC)
		nattr = *attr;
	else
		return EINVAL;

	/* Fetch misc. attributes from the attr structure. */
	name = NULL;
	if ((p = nattr.pta_private) != NULL)
		if (p->ptap_name[0] != '\0')
			if ((name = strdup(p->ptap_name)) == NULL)
				return ENOMEM;

	newthread = NULL;

	/*
	 * Try to reclaim a dead thread.
	 */
	if (!PTQ_EMPTY(&pthread__deadqueue)) {
		pthread_mutex_lock(&pthread__deadqueue_lock);
		newthread = PTQ_FIRST(&pthread__deadqueue);
		if (newthread != NULL) {
			PTQ_REMOVE(&pthread__deadqueue, newthread, pt_deadq);
			pthread_mutex_unlock(&pthread__deadqueue_lock);
			/* Still running? */
			if (newthread->pt_lwpctl->lc_curcpu !=
			    LWPCTL_CPU_EXITED &&
			    (_lwp_kill(newthread->pt_lid, 0) == 0 ||
			    errno != ESRCH)) {
				pthread_mutex_lock(&pthread__deadqueue_lock);
				PTQ_INSERT_TAIL(&pthread__deadqueue,
				    newthread, pt_deadq);
				pthread_mutex_unlock(&pthread__deadqueue_lock);
				newthread = NULL;
			}
		} else
			pthread_mutex_unlock(&pthread__deadqueue_lock);
	}

	/*
	 * If necessary set up a stack, allocate space for a pthread_st,
	 * and initialize it.
	 */
	if (newthread == NULL) {
		ret = pthread__stackalloc(&newthread);
		if (ret != 0) {
			if (name)
				free(name);
			return ret;
		}

		/* This is used only when creating the thread. */
		_INITCONTEXT_U(&newthread->pt_uc);
#ifdef PTHREAD_MACHINE_HAS_ID_REGISTER
		pthread__uc_id(&newthread->pt_uc) = newthread;
#endif
		newthread->pt_uc.uc_stack = newthread->pt_stack;
		newthread->pt_uc.uc_link = NULL;

		/* Add to list of all threads. */
		pthread_rwlock_wrlock(&pthread__alltree_lock);
		PTQ_INSERT_TAIL(&pthread__allqueue, newthread, pt_allq);
		RB_INSERT(__pthread__alltree, &pthread__alltree, newthread);
		pthread_rwlock_unlock(&pthread__alltree_lock);

		/* Will be reset by the thread upon exit. */
		pthread__initthread(newthread);
	}

	/*
	 * Create the new LWP.
	 */
	pthread__scrubthread(newthread, name, nattr.pta_flags);
	makecontext(&newthread->pt_uc, pthread__create_tramp, 3,
	    newthread, startfunc, arg);

	flag = LWP_DETACHED;
	if ((newthread->pt_flags & PT_FLAG_SUSPENDED) != 0)
		flag |= LWP_SUSPENDED;
	ret = _lwp_create(&newthread->pt_uc, flag, &newthread->pt_lid);
	if (ret != 0) {
		free(name);
		newthread->pt_state = PT_STATE_DEAD;
		pthread_mutex_lock(&pthread__deadqueue_lock);
		PTQ_INSERT_HEAD(&pthread__deadqueue, newthread, pt_deadq);
		pthread_mutex_unlock(&pthread__deadqueue_lock);
		return ret;
	}

	*thread = newthread;

	return 0;
}


static void
pthread__create_tramp(pthread_t self, void *(*start)(void *), void *arg)
{
	void *retval;

#ifdef PTHREAD__HAVE_THREADREG
	/* Set up identity register. */
	pthread__threadreg_set(self);
#endif

	/*
	 * Throw away some stack in a feeble attempt to reduce cache
	 * thrash.  May help for SMT processors.  XXX We should not
	 * be allocating stacks on fixed 2MB boundaries.  Needs a
	 * thread register or decent thread local storage.  Note
	 * that pt_lid may not be set by this point, but we don't
	 * care.
	 */
	(void)alloca(((unsigned)self->pt_lid & 7) << 8);

	if (self->pt_name != NULL) {
		pthread_mutex_lock(&self->pt_lock);
		if (self->pt_name != NULL)
			(void)_lwp_setname(0, self->pt_name);
		pthread_mutex_unlock(&self->pt_lock);
	}

	(void)_lwp_ctl(LWPCTL_FEATURE_CURCPU, &self->pt_lwpctl);

	retval = (*start)(arg);

	pthread_exit(retval);

	/*NOTREACHED*/
	pthread__abort();
}

int
pthread_suspend_np(pthread_t thread)
{
	pthread_t self;

	self = pthread__self();
	if (self == thread) {
		return EDEADLK;
	}
	if (pthread__find(thread) != 0)
		return ESRCH;
	if (_lwp_suspend(thread->pt_lid) == 0)
		return 0;
	return errno;
}

int
pthread_resume_np(pthread_t thread)
{
 
	if (pthread__find(thread) != 0)
		return ESRCH;
	if (_lwp_continue(thread->pt_lid) == 0)
		return 0;
	return errno;
}

void
pthread_exit(void *retval)
{
	pthread_t self;
	struct pt_clean_t *cleanup;
	char *name;

	self = pthread__self();

	/* Disable cancellability. */
	pthread_mutex_lock(&self->pt_lock);
	self->pt_flags |= PT_FLAG_CS_DISABLED;
	self->pt_cancel = 0;

	/* Call any cancellation cleanup handlers */
	if (!PTQ_EMPTY(&self->pt_cleanup_stack)) {
		pthread_mutex_unlock(&self->pt_lock);
		while (!PTQ_EMPTY(&self->pt_cleanup_stack)) {
			cleanup = PTQ_FIRST(&self->pt_cleanup_stack);
			PTQ_REMOVE(&self->pt_cleanup_stack, cleanup, ptc_next);
			(*cleanup->ptc_cleanup)(cleanup->ptc_arg);
		}
		pthread_mutex_lock(&self->pt_lock);
	}

	/* Perform cleanup of thread-specific data */
	pthread__destroy_tsd(self);

	/* Signal our exit. */
	self->pt_exitval = retval;
	if (self->pt_flags & PT_FLAG_DETACHED) {
		self->pt_state = PT_STATE_DEAD;
		name = self->pt_name;
		self->pt_name = NULL;
		pthread_mutex_unlock(&self->pt_lock);
		if (name != NULL)
			free(name);
		pthread_mutex_lock(&pthread__deadqueue_lock);
		PTQ_INSERT_TAIL(&pthread__deadqueue, self, pt_deadq);
		pthread_mutex_unlock(&pthread__deadqueue_lock);
		_lwp_exit();
	} else {
		self->pt_state = PT_STATE_ZOMBIE;
		pthread_cond_broadcast(&self->pt_joiners);
		pthread_mutex_unlock(&self->pt_lock);
		/* Note: name will be freed by the joiner. */
		_lwp_exit();
	}

	/*NOTREACHED*/
	pthread__abort();
	exit(1);
}


int
pthread_join(pthread_t thread, void **valptr)
{
	pthread_t self;
	int error;

	self = pthread__self();

	if (pthread__find(thread) != 0)
		return ESRCH;

	if (thread->pt_magic != PT_MAGIC)
		return EINVAL;

	if (thread == self)
		return EDEADLK;

	self->pt_droplock = &thread->pt_lock;
	pthread_mutex_lock(&thread->pt_lock);
	for (;;) {
		if (thread->pt_state == PT_STATE_ZOMBIE)
			break;
		if (thread->pt_state == PT_STATE_DEAD) {
			pthread_mutex_unlock(&thread->pt_lock);
			self->pt_droplock = NULL;
			return ESRCH;
		}
		if ((thread->pt_flags & PT_FLAG_DETACHED) != 0) {
			pthread_mutex_unlock(&thread->pt_lock);
			self->pt_droplock = NULL;
			return EINVAL;
		}
		error = pthread_cond_wait(&thread->pt_joiners,
		    &thread->pt_lock);
		if (error != 0) {
			pthread__errorfunc(__FILE__, __LINE__,
			    __func__, "unexpected return from cond_wait()");
		}

	}
	if (valptr != NULL)
		*valptr = thread->pt_exitval;
	/* pthread__reap() will drop the lock. */
	pthread__reap(thread);
	self->pt_droplock = NULL;

	return 0;
}

static void
pthread__reap(pthread_t thread)
{
	char *name;

	name = thread->pt_name;
	thread->pt_name = NULL;
	thread->pt_state = PT_STATE_DEAD;
	pthread_mutex_unlock(&thread->pt_lock);

	pthread_mutex_lock(&pthread__deadqueue_lock);
	PTQ_INSERT_HEAD(&pthread__deadqueue, thread, pt_deadq);
	pthread_mutex_unlock(&pthread__deadqueue_lock);

	if (name != NULL)
		free(name);
}

int
pthread_equal(pthread_t t1, pthread_t t2)
{

	/* Nothing special here. */
	return (t1 == t2);
}


int
pthread_detach(pthread_t thread)
{

	if (pthread__find(thread) != 0)
		return ESRCH;

	if (thread->pt_magic != PT_MAGIC)
		return EINVAL;

	pthread_mutex_lock(&thread->pt_lock);
	thread->pt_flags |= PT_FLAG_DETACHED;
	if (thread->pt_state == PT_STATE_ZOMBIE) {
		/* pthread__reap() will drop the lock. */
		pthread__reap(thread);
	} else {
		/*
		 * Not valid for threads to be waiting in
		 * pthread_join() (there are intractable
		 * sync issues from the application
		 * perspective), but give those threads
		 * a chance anyway.
		 */
		pthread_cond_broadcast(&thread->pt_joiners);
		pthread_mutex_unlock(&thread->pt_lock);
	}

	return 0;
}


int
pthread_getname_np(pthread_t thread, char *name, size_t len)
{

	if (pthread__find(thread) != 0)
		return ESRCH;

	if (thread->pt_magic != PT_MAGIC)
		return EINVAL;

	pthread_mutex_lock(&thread->pt_lock);
	if (thread->pt_name == NULL)
		name[0] = '\0';
	else
		strlcpy(name, thread->pt_name, len);
	pthread_mutex_unlock(&thread->pt_lock);

	return 0;
}


int
pthread_setname_np(pthread_t thread, const char *name, void *arg)
{
	char *oldname, *cp, newname[PTHREAD_MAX_NAMELEN_NP];
	int namelen;

	if (pthread__find(thread) != 0)
		return ESRCH;

	if (thread->pt_magic != PT_MAGIC)
		return EINVAL;

	namelen = snprintf(newname, sizeof(newname), name, arg);
	if (namelen >= PTHREAD_MAX_NAMELEN_NP)
		return EINVAL;

	cp = strdup(newname);
	if (cp == NULL)
		return ENOMEM;

	pthread_mutex_lock(&thread->pt_lock);
	oldname = thread->pt_name;
	thread->pt_name = cp;
	(void)_lwp_setname(thread->pt_lid, cp);
	pthread_mutex_unlock(&thread->pt_lock);

	if (oldname != NULL)
		free(oldname);

	return 0;
}



/*
 * XXX There should be a way for applications to use the efficent
 *  inline version, but there are opacity/namespace issues.
 */
pthread_t
pthread_self(void)
{

	return pthread__self();
}


int
pthread_cancel(pthread_t thread)
{

	if (pthread__find(thread) != 0)
		return ESRCH;
	pthread_mutex_lock(&thread->pt_lock);
	thread->pt_flags |= PT_FLAG_CS_PENDING;
	if ((thread->pt_flags & PT_FLAG_CS_DISABLED) == 0) {
		thread->pt_cancel = 1;
		pthread_mutex_unlock(&thread->pt_lock);
		_lwp_wakeup(thread->pt_lid);
	} else
		pthread_mutex_unlock(&thread->pt_lock);

	return 0;
}


int
pthread_setcancelstate(int state, int *oldstate)
{
	pthread_t self;
	int retval;

	self = pthread__self();
	retval = 0;

	pthread_mutex_lock(&self->pt_lock);

	if (oldstate != NULL) {
		if (self->pt_flags & PT_FLAG_CS_DISABLED)
			*oldstate = PTHREAD_CANCEL_DISABLE;
		else
			*oldstate = PTHREAD_CANCEL_ENABLE;
	}

	if (state == PTHREAD_CANCEL_DISABLE) {
		self->pt_flags |= PT_FLAG_CS_DISABLED;
		if (self->pt_cancel) {
			self->pt_flags |= PT_FLAG_CS_PENDING;
			self->pt_cancel = 0;
		}
	} else if (state == PTHREAD_CANCEL_ENABLE) {
		self->pt_flags &= ~PT_FLAG_CS_DISABLED;
		/*
		 * If a cancellation was requested while cancellation
		 * was disabled, note that fact for future
		 * cancellation tests.
		 */
		if (self->pt_flags & PT_FLAG_CS_PENDING) {
			self->pt_cancel = 1;
			/* This is not a deferred cancellation point. */
			if (self->pt_flags & PT_FLAG_CS_ASYNC) {
				pthread_mutex_unlock(&self->pt_lock);
				pthread__cancelled();
			}
		}
	} else
		retval = EINVAL;

	pthread_mutex_unlock(&self->pt_lock);

	return retval;
}


int
pthread_setcanceltype(int type, int *oldtype)
{
	pthread_t self;
	int retval;

	self = pthread__self();
	retval = 0;

	pthread_mutex_lock(&self->pt_lock);

	if (oldtype != NULL) {
		if (self->pt_flags & PT_FLAG_CS_ASYNC)
			*oldtype = PTHREAD_CANCEL_ASYNCHRONOUS;
		else
			*oldtype = PTHREAD_CANCEL_DEFERRED;
	}

	if (type == PTHREAD_CANCEL_ASYNCHRONOUS) {
		self->pt_flags |= PT_FLAG_CS_ASYNC;
		if (self->pt_cancel) {
			pthread_mutex_unlock(&self->pt_lock);
			pthread__cancelled();
		}
	} else if (type == PTHREAD_CANCEL_DEFERRED)
		self->pt_flags &= ~PT_FLAG_CS_ASYNC;
	else
		retval = EINVAL;

	pthread_mutex_unlock(&self->pt_lock);

	return retval;
}


void
pthread_testcancel(void)
{
	pthread_t self;

	self = pthread__self();
	if (self->pt_cancel)
		pthread__cancelled();
}


/*
 * POSIX requires that certain functions return an error rather than
 * invoking undefined behavior even when handed completely bogus
 * pthread_t values, e.g. stack garbage or (pthread_t)666. This
 * utility routine searches the list of threads for the pthread_t
 * value without dereferencing it.
 */
int
pthread__find(pthread_t id)
{
	pthread_t target;

	pthread_rwlock_rdlock(&pthread__alltree_lock);
	/* LINTED */
	target = RB_FIND(__pthread__alltree, &pthread__alltree, id);
	pthread_rwlock_unlock(&pthread__alltree_lock);

	if (target == NULL || target->pt_state == PT_STATE_DEAD)
		return ESRCH;

	return 0;
}


void
pthread__testcancel(pthread_t self)
{

	if (self->pt_cancel)
		pthread__cancelled();
}


void
pthread__cancelled(void)
{
	pthread_mutex_t *droplock;
	pthread_t self;

	self = pthread__self();
	droplock = self->pt_droplock;
	self->pt_droplock = NULL;

	if (droplock != NULL && pthread_mutex_held_np(droplock))
		pthread_mutex_unlock(droplock);

	pthread_exit(PTHREAD_CANCELED);
}


void
pthread__cleanup_push(void (*cleanup)(void *), void *arg, void *store)
{
	pthread_t self;
	struct pt_clean_t *entry;

	self = pthread__self();
	entry = store;
	entry->ptc_cleanup = cleanup;
	entry->ptc_arg = arg;
	PTQ_INSERT_HEAD(&self->pt_cleanup_stack, entry, ptc_next);
}


void
pthread__cleanup_pop(int ex, void *store)
{
	pthread_t self;
	struct pt_clean_t *entry;

	self = pthread__self();
	entry = store;

	PTQ_REMOVE(&self->pt_cleanup_stack, entry, ptc_next);
	if (ex)
		(*entry->ptc_cleanup)(entry->ptc_arg);
}


int *
pthread__errno(void)
{
	pthread_t self;

	self = pthread__self();

	return &(self->pt_errno);
}

ssize_t	_sys_write(int, const void *, size_t);

void
pthread__assertfunc(const char *file, int line, const char *function,
		    const char *expr)
{
	char buf[1024];
	int len;

	/*
	 * snprintf should not acquire any locks, or we could
	 * end up deadlocked if the assert caller held locks.
	 */
	len = snprintf(buf, 1024, 
	    "assertion \"%s\" failed: file \"%s\", line %d%s%s%s\n",
	    expr, file, line,
	    function ? ", function \"" : "",
	    function ? function : "",
	    function ? "\"" : "");

	_sys_write(STDERR_FILENO, buf, (size_t)len);
	(void)kill(getpid(), SIGABRT);

	_exit(1);
}


void
pthread__errorfunc(const char *file, int line, const char *function,
		   const char *msg)
{
	char buf[1024];
	size_t len;
	
	if (pthread__diagassert == 0)
		return;

	/*
	 * snprintf should not acquire any locks, or we could
	 * end up deadlocked if the assert caller held locks.
	 */
	len = snprintf(buf, 1024, 
	    "%s: Error detected by libpthread: %s.\n"
	    "Detected by file \"%s\", line %d%s%s%s.\n"
	    "See pthread(3) for information.\n",
	    getprogname(), msg, file, line,
	    function ? ", function \"" : "",
	    function ? function : "",
	    function ? "\"" : "");

	if (pthread__diagassert & DIAGASSERT_STDERR)
		_sys_write(STDERR_FILENO, buf, len);

	if (pthread__diagassert & DIAGASSERT_SYSLOG)
		syslog(LOG_DEBUG | LOG_USER, "%s", buf);

	if (pthread__diagassert & DIAGASSERT_ABORT) {
		(void)kill(getpid(), SIGABRT);
		_exit(1);
	}
}

/*
 * Thread park/unpark operations.  The kernel operations are
 * modelled after a brief description from "Multithreading in
 * the Solaris Operating Environment":
 *
 * http://www.sun.com/software/whitepapers/solaris9/multithread.pdf
 */

#define	OOPS(msg)			\
    pthread__errorfunc(__FILE__, __LINE__, __func__, msg)

int
pthread__park(pthread_t self, pthread_spin_t *lock,
	      pthread_queue_t *queue, const struct timespec *abstime,
	      int cancelpt, const void *hint)
{
	int rv, error;
	void *obj;

	/* Clear the willpark flag, since we're about to block. */
	self->pt_willpark = 0;

	/*
	 * For non-interlocked release of mutexes we need a store
	 * barrier before incrementing pt_blocking away from zero. 
	 * This is provided by the caller (it will release an
	 * interlock, or do an explicit barrier).
	 */
	self->pt_blocking++;

	/*
	 * Wait until we are awoken by a pending unpark operation,
	 * a signal, an unpark posted after we have gone asleep,
	 * or an expired timeout.
	 *
	 * It is fine to test the value of both pt_sleepobj and
	 * pt_sleeponq without holding any locks, because:
	 *
	 * o Only the blocking thread (this thread) ever sets them
	 *   to a non-NULL value.
	 *
	 * o Other threads may set them NULL, but if they do so they
	 *   must also make this thread return from _lwp_park.
	 *
	 * o _lwp_park, _lwp_unpark and _lwp_unpark_all are system
	 *   calls and all make use of spinlocks in the kernel.  So
	 *   these system calls act as full memory barriers, and will
	 *   ensure that the calling CPU's store buffers are drained.
	 *   In combination with the spinlock release before unpark,
	 *   this means that modification of pt_sleepobj/onq by another
	 *   thread will become globally visible before that thread
	 *   schedules an unpark operation on this thread.
	 *
	 * Note: the test in the while() statement dodges the park op if
	 * we have already been awoken, unless there is another thread to
	 * awaken.  This saves a syscall - if we were already awakened,
	 * the next call to _lwp_park() would need to return early in order
	 * to eat the previous wakeup.
	 */
	rv = 0;
	while ((self->pt_sleepobj != NULL || self->pt_unpark != 0) && rv == 0) {
		/*
		 * If we deferred unparking a thread, arrange to
		 * have _lwp_park() restart it before blocking.
		 */
		error = _lwp_park(abstime, self->pt_unpark, hint,
		    self->pt_unparkhint);
		self->pt_unpark = 0;
		if (error != 0) {
			switch (rv = errno) {
			case EINTR:
			case EALREADY:
				rv = 0;
				break;
			case ETIMEDOUT:
				break;
			default:
				OOPS("_lwp_park failed");
				break;
			}
		}
		/* Check for cancellation. */
		if (cancelpt && self->pt_cancel)
			rv = EINTR;
	}

	/*
	 * If we have been awoken early but are still on the queue,
	 * then remove ourself.  Again, it's safe to do the test
	 * without holding any locks.
	 */
	if (__predict_false(self->pt_sleeponq)) {
		pthread__spinlock(self, lock);
		if (self->pt_sleeponq) {
			PTQ_REMOVE(queue, self, pt_sleep);
			obj = self->pt_sleepobj;
			self->pt_sleepobj = NULL;
			self->pt_sleeponq = 0;
			if (obj != NULL && self->pt_early != NULL)
				(*self->pt_early)(obj);
		}
		pthread__spinunlock(self, lock);
	}
	self->pt_early = NULL;
	self->pt_blocking--;

	return rv;
}

void
pthread__unpark(pthread_t self, pthread_spin_t *lock,
		pthread_queue_t *queue, pthread_t target)
{
	int rv;

	if (target == NULL) {
		pthread__spinunlock(self, lock);
		return;
	}

	/*
	 * Easy: the thread has already been removed from
	 * the queue, so just awaken it.
	 */
	target->pt_sleepobj = NULL;
	target->pt_sleeponq = 0;

	/*
	 * Releasing the spinlock serves as a store barrier,
	 * which ensures that all our modifications are visible
	 * to the thread in pthread__park() before the unpark
	 * operation is set in motion.
	 */
	pthread__spinunlock(self, lock);

	/*
	 * If the calling thread is about to block, defer
	 * unparking the target until _lwp_park() is called.
	 */
	if (self->pt_willpark && self->pt_unpark == 0) {
		self->pt_unpark = target->pt_lid;
		self->pt_unparkhint = queue;
	} else {
		rv = _lwp_unpark(target->pt_lid, queue);
		if (rv != 0 && errno != EALREADY && errno != EINTR) {
			OOPS("_lwp_unpark failed");
		}
	}
}

void
pthread__unpark_all(pthread_t self, pthread_spin_t *lock,
		    pthread_queue_t *queue)
{
	ssize_t n, rv;
	pthread_t thread, next;
	void *wakeobj;

	if (PTQ_EMPTY(queue) && self->pt_nwaiters == 0) {
		pthread__spinunlock(self, lock);
		return;
	}

	wakeobj = queue;

	for (;;) {
		/*
		 * Pull waiters from the queue and add to this
		 * thread's waiters list.
		 */
		thread = PTQ_FIRST(queue);
		for (n = self->pt_nwaiters, self->pt_nwaiters = 0;
		    n < pthread__unpark_max && thread != NULL;
		    thread = next) {
			/*
			 * If the sleepobj pointer is non-NULL, it
			 * means one of two things:
			 *
			 * o The thread has awoken early, spun
			 *   through application code and is
			 *   once more asleep on this object.
			 *
			 * o This is a new thread that has blocked
			 *   on the object after we have released
			 *   the interlock in this loop.
			 *
			 * In both cases we shouldn't remove the
			 * thread from the queue.
			 */
			next = PTQ_NEXT(thread, pt_sleep);
			if (thread->pt_sleepobj != wakeobj)
				continue;
			thread->pt_sleepobj = NULL;
			thread->pt_sleeponq = 0;
			self->pt_waiters[n++] = thread->pt_lid;
			PTQ_REMOVE(queue, thread, pt_sleep);
		}

		/*
		 * Releasing the spinlock serves as a store barrier,
		 * which ensures that all our modifications are visible
		 * to the thread in pthread__park() before the unpark
		 * operation is set in motion.
		 */
		switch (n) {
		case 0:
			pthread__spinunlock(self, lock);
			return;
		case 1:
			/*
			 * If the calling thread is about to block,
			 * defer unparking the target until _lwp_park()
			 * is called.
			 */
			pthread__spinunlock(self, lock);
			if (self->pt_willpark && self->pt_unpark == 0) {
				self->pt_unpark = self->pt_waiters[0];
				self->pt_unparkhint = queue;
				return;
			}
			rv = (ssize_t)_lwp_unpark(self->pt_waiters[0], queue);
			if (rv != 0 && errno != EALREADY && errno != EINTR) {
				OOPS("_lwp_unpark failed");
			}
			return;
		default:
			/*
			 * Clear all sleepobj pointers, since we
			 * release the spin lock before awkening
			 * everybody, and must synchronise with
			 * pthread__park().
			 */
			while (thread != NULL) {
				thread->pt_sleepobj = NULL;
				thread = PTQ_NEXT(thread, pt_sleep);
			}
			/* 
			 * Now only interested in waking threads
			 * marked to be woken (sleepobj == NULL).
			 */
			wakeobj = NULL;
			pthread__spinunlock(self, lock);
			rv = _lwp_unpark_all(self->pt_waiters, (size_t)n,
			    queue);
			if (rv != 0 && errno != EINTR) {
				OOPS("_lwp_unpark_all failed");
			}
			break;
		}
		pthread__spinlock(self, lock);
	}
}

#undef	OOPS

/*
 * Allocate a stack for a thread, and set it up. It needs to be aligned, so 
 * that a thread can find itself by its stack pointer. 
 */
static int
pthread__stackalloc(pthread_t *newt)
{
	void *addr;

	addr = mmap(NULL, pthread__stacksize, PROT_READ|PROT_WRITE,
	    MAP_ANON|MAP_PRIVATE | MAP_ALIGNED(pthread__stacksize_lg),
	    -1, (off_t)0);

	if (addr == MAP_FAILED)
		return ENOMEM;

	pthread__assert(((intptr_t)addr & pthread__stackmask) == 0);

	return pthread__stackid_setup(addr, pthread__stacksize, newt); 
}


/*
 * Set up the slightly special stack for the "initial" thread, which
 * runs on the normal system stack, and thus gets slightly different
 * treatment.
 */
static void
pthread__initmain(pthread_t *newt)
{
	struct rlimit slimit;
	size_t pagesize;
	pthread_t t;
	void *base;
	size_t size;
	int error, ret;
	char *value;

	pagesize = (size_t)sysconf(_SC_PAGESIZE);
	pthread__stacksize = 0;
	ret = getrlimit(RLIMIT_STACK, &slimit);
	if (ret == -1)
		err(1, "Couldn't get stack resource consumption limits");

	value = pthread__getenv("PTHREAD_STACKSIZE");
	if (value != NULL) {
		pthread__stacksize = atoi(value) * 1024;
		if (pthread__stacksize > slimit.rlim_cur)
			pthread__stacksize = (size_t)slimit.rlim_cur;
	}
	if (pthread__stacksize == 0)
		pthread__stacksize = (size_t)slimit.rlim_cur;
	if (pthread__stacksize < 4 * pagesize)
		errx(1, "Stacksize limit is too low, minimum %zd kbyte.",
		    4 * pagesize / 1024);

	pthread__stacksize_lg = -1;
	while (pthread__stacksize) {
		pthread__stacksize >>= 1;
		pthread__stacksize_lg++;
	}

	pthread__stacksize = (1 << pthread__stacksize_lg);
	pthread__stackmask = pthread__stacksize - 1;
	pthread__threadmask = ~pthread__stackmask;

	base = (void *)(pthread__sp() & pthread__threadmask);
	size = pthread__stacksize;

	error = pthread__stackid_setup(base, size, &t);
	if (error) {
		/* XXX */
		errx(2, "failed to setup main thread: error=%d", error);
	}

	*newt = t;

#ifdef PTHREAD__HAVE_THREADREG
	/* Set up identity register. */
	pthread__threadreg_set(t);
#endif
}

static int
/*ARGSUSED*/
pthread__stackid_setup(void *base, size_t size, pthread_t *tp)
{
	pthread_t t;
	void *redaddr;
	size_t pagesize;
	int ret;

	t = base;
	pagesize = (size_t)sysconf(_SC_PAGESIZE);

	/*
	 * Put a pointer to the pthread in the bottom (but
         * redzone-protected section) of the stack. 
	 */
	redaddr = STACK_SHRINK(STACK_MAX(base, size), pagesize);
	t->pt_stack.ss_size = size - 2 * pagesize;
#ifdef __MACHINE_STACK_GROWS_UP
	t->pt_stack.ss_sp = (char *)(void *)base + pagesize;
#else
	t->pt_stack.ss_sp = (char *)(void *)base + 2 * pagesize;
#endif

	/* Protect the next-to-bottom stack page as a red zone. */
	ret = mprotect(redaddr, pagesize, PROT_NONE);
	if (ret == -1) {
		return errno;
	}
	*tp = t;
	return 0;
}

#ifndef lint
static int
pthread__cmp(struct __pthread_st *a, struct __pthread_st *b)
{
	return b - a;
}
RB_GENERATE_STATIC(__pthread__alltree, __pthread_st, pt_alltree, pthread__cmp)
#endif

/* Because getenv() wants to use locks. */
char *
pthread__getenv(const char *name)
{
	extern char *__findenv(const char *, int *);
	int off;

	return __findenv(name, &off);
}