xref: /netbsd-src/lib/libpthread/pthread.c (revision 075022b349321510ad14036d70908681ed02f117)

/*	$NetBSD: pthread.c,v 1.28 2003/07/21 22:24:09 nathanw Exp $	*/

/*-
 * Copyright (c) 2001,2002,2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nathan J. Williams.
 *
 * 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 1.28 2003/07/21 22:24:09 nathanw Exp $");

#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"

#ifdef PTHREAD_MAIN_DEBUG
#define SDPRINTF(x) DPRINTF(x)
#else
#define SDPRINTF(x)
#endif

static void	pthread__create_tramp(void *(*start)(void *), void *arg);

int pthread__started;

pthread_spin_t pthread__allqueue_lock;
struct pthread_queue_t pthread__allqueue;

pthread_spin_t pthread__deadqueue_lock;
struct pthread_queue_t pthread__deadqueue;
struct pthread_queue_t pthread__reidlequeue;

static int nthreads;
static int nextthread;
static pthread_spin_t nextthread_lock;
static pthread_attr_t pthread_default_attr;

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

static int pthread__diagassert = DIAGASSERT_ABORT | DIAGASSERT_STDERR;

pthread_spin_t pthread__runqueue_lock;
struct pthread_queue_t pthread__runqueue;
struct pthread_queue_t pthread__idlequeue;

__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)

/*
 * 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;
extern int pthread__sched_binder;
extern struct pthread_queue_t pthread__nanosleeping;

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__sched_binder,
	&pthread__nanosleeping
};

/*
 * 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;
	extern int __isthreaded;

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

	/* Basic data structure setup */
	pthread_attr_init(&pthread_default_attr);
	PTQ_INIT(&pthread__allqueue);
	PTQ_INIT(&pthread__deadqueue);
	PTQ_INIT(&pthread__reidlequeue);
	PTQ_INIT(&pthread__runqueue);
	PTQ_INIT(&pthread__idlequeue);
	nthreads = 1;

	/* Create the thread structure corresponding to main() */
	pthread__initmain(&first);
	pthread__initthread(first, first);
	first->pt_state = PT_STATE_RUNNING;
	sigprocmask(0, NULL, &first->pt_sigmask);
	PTQ_INSERT_HEAD(&pthread__allqueue, first, pt_allq);

	/* Start subsystems */
	pthread__signal_init();
	PTHREAD_MD_INIT
#ifdef PTHREAD__DEBUG
	pthread__debug_init();
#endif

	for (p = 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. */
	__isthreaded = 1;
}

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)
{
	pthread_t self, idle;
	int i, ret;

	self = pthread__self(); /* should be the "main()" thread */

	/*
	 * 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__alarm_init();

	pthread_atfork(NULL, NULL, pthread__child_callback);

	/* Create idle threads */
	for (i = 0; i < NIDLETHREADS; i++) {
		ret = pthread__stackalloc(&idle);
		if (ret != 0)
			err(1, "Couldn't allocate stack for idle thread!");
		pthread__initthread(self, idle);
		sigfillset(&idle->pt_sigmask);
		idle->pt_type = PT_THREAD_IDLE;
		PTQ_INSERT_HEAD(&pthread__allqueue, idle, pt_allq);
		pthread__sched_idle(self, idle);
	}

	/* Start up the SA subsystem */
	pthread__sa_start();
	SDPRINTF(("(pthread__start %p) Started.\n", self));
}


/* General-purpose thread data structure sanitization. */
void
pthread__initthread(pthread_t self, pthread_t t)
{
	int id;

	pthread_spinlock(self, &nextthread_lock);
	id = nextthread;
	nextthread++;
	pthread_spinunlock(self, &nextthread_lock);
	t->pt_num = id;

	t->pt_magic = PT_MAGIC;
	t->pt_type = PT_THREAD_NORMAL;
	t->pt_state = PT_STATE_RUNNABLE;
	pthread_lockinit(&t->pt_statelock);
	pthread_lockinit(&t->pt_flaglock);
	t->pt_spinlocks = 0;
	t->pt_next = NULL;
	t->pt_exitval = NULL;
	t->pt_flags = 0;
	t->pt_cancel = 0;
	t->pt_errno = 0;
	t->pt_parent = NULL;
	t->pt_heldlock = NULL;
	t->pt_switchto = NULL;
	t->pt_trapuc = NULL;
	sigemptyset(&t->pt_siglist);
	sigemptyset(&t->pt_sigmask);
	pthread_lockinit(&t->pt_siglock);
	PTQ_INIT(&t->pt_joiners);
	pthread_lockinit(&t->pt_join_lock);
	PTQ_INIT(&t->pt_cleanup_stack);
	memset(&t->pt_specific, 0, sizeof(int) * PTHREAD_KEYS_MAX);
	t->pt_name = NULL;
#ifdef PTHREAD__DEBUG
	t->blocks = 0;
	t->preempts = 0;
	t->rescheds = 0;
#endif
}


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

	PTHREADD_ADD(PTHREADD_CREATE);

	/*
	 * 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;

	self = pthread__self();

	pthread_spinlock(self, &pthread__deadqueue_lock);
	if (!PTQ_EMPTY(&pthread__deadqueue)) {
		newthread = PTQ_FIRST(&pthread__deadqueue);
		PTQ_REMOVE(&pthread__deadqueue, newthread, pt_allq);
		pthread_spinunlock(self, &pthread__deadqueue_lock);
	} else {
		pthread_spinunlock(self, &pthread__deadqueue_lock);
		/* Set up a stack and allocate space for a pthread_st. */
		ret = pthread__stackalloc(&newthread);
		if (ret != 0)
			return ret;
	}

	/* 2. Set up state. */
	pthread__initthread(self, newthread);
	newthread->pt_flags = nattr.pta_flags;
	newthread->pt_sigmask = self->pt_sigmask;

	/* 3. Set up misc. attributes. */
	newthread->pt_name = name;

	/*
	 * 4. Set up context.
	 *
	 * The pt_uc pointer points to a location safely below the
	 * stack start; this is arranged by pthread__stackalloc().
	 */
	_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;
	makecontext(newthread->pt_uc, pthread__create_tramp, 2,
	    startfunc, arg);

	/* 5. Add to list of all threads. */
	pthread_spinlock(self, &pthread__allqueue_lock);
	PTQ_INSERT_HEAD(&pthread__allqueue, newthread, pt_allq);
	nthreads++;
	pthread_spinunlock(self, &pthread__allqueue_lock);

	SDPRINTF(("(pthread_create %p) Created new thread %p (name pointer %p).\n", self, newthread, newthread->pt_name));
	/* 6. Put on run queue. */
	pthread__sched(self, newthread);

	*thread = newthread;

	return 0;
}


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

	retval = start(arg);

	pthread_exit(retval);

	/*NOTREACHED*/
	pthread__abort();
}


/*
 * Other threads will switch to the idle thread so that they
 * can dispose of any awkward locks or recycle upcall state.
 */
void
pthread__idle(void)
{
	pthread_t self;

	PTHREADD_ADD(PTHREADD_IDLE);
	self = pthread__self();
	SDPRINTF(("(pthread__idle %p).\n", self));

	/*
	 * The drill here is that we want to yield the processor,
	 * but for the thread itself to be recovered, we need to be on
	 * a list somewhere for the thread system to know about us.
	 */
	pthread_spinlock(self, &pthread__deadqueue_lock);
	PTQ_INSERT_TAIL(&pthread__reidlequeue, self, pt_runq);
	/* Don't need a flag lock; nothing else has a handle on this thread */
	self->pt_flags |= PT_FLAG_IDLED;
	pthread_spinunlock(self, &pthread__deadqueue_lock);

	/*
	 * If we get to run this, then no preemption has happened
	 * (because the upcall handler will not continue an idle thread with
	 * PT_FLAG_IDLED set), and so we can yield the processor safely.
	 */
	SDPRINTF(("(pthread__idle %p) yielding.\n", self));
	sa_yield();

	/* NOTREACHED */
	self->pt_spinlocks++; /* XXX make sure we get to finish the assert! */
	SDPRINTF(("(pthread__idle %p) Returned! Error.\n", self));
	pthread__abort();
}


void
pthread_exit(void *retval)
{
	pthread_t self;
	struct pt_clean_t *cleanup;
	char *name;
	int nt, flags;

	self = pthread__self();
	SDPRINTF(("(pthread_exit %p) Exiting (status %p, flags %x, cancel %d).\n", self, retval, self->pt_flags, self->pt_cancel));

	/* Disable cancellability. */
	pthread_spinlock(self, &self->pt_flaglock);
	self->pt_flags |= PT_FLAG_CS_DISABLED;
	flags = self->pt_flags;
	self->pt_cancel = 0;
	pthread_spinunlock(self, &self->pt_flaglock);

	/* Call any cancellation cleanup handlers */
	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);
	}

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

	self->pt_exitval = retval;

	if (flags & PT_FLAG_DETACHED) {
		name = self->pt_name;
		self->pt_name = NULL;

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

		pthread_spinlock(self, &pthread__allqueue_lock);
		PTQ_REMOVE(&pthread__allqueue, self, pt_allq);
		nthreads--;
		nt = nthreads;
		pthread_spinunlock(self, &pthread__allqueue_lock);

		self->pt_state = PT_STATE_DEAD;
		if (nt == 0) {
			/* Whoah, we're the last one. Time to go. */
			exit(0);
		}

		/* Yeah, yeah, doing work while we're dead is tacky. */
		pthread_spinlock(self, &pthread__deadqueue_lock);
		PTQ_INSERT_HEAD(&pthread__deadqueue, self, pt_allq);
		pthread__block(self, &pthread__deadqueue_lock);
	} else {
		/* Note: name will be freed by the joiner. */
		pthread_spinlock(self, &self->pt_join_lock);
		pthread_spinlock(self, &pthread__allqueue_lock);
		nthreads--;
		nt = nthreads;
		self->pt_state = PT_STATE_ZOMBIE;
		pthread_spinunlock(self, &pthread__allqueue_lock);
		if (nt == 0) {
			/* Whoah, we're the last one. Time to go. */
			exit(0);
		}
		/*
		 * Wake up all the potential joiners. Only one can win.
		 * (Can you say "Thundering Herd"? I knew you could.)
		 */
		pthread__sched_sleepers(self, &self->pt_joiners);
		pthread__block(self, &self->pt_join_lock);
	}

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


int
pthread_join(pthread_t thread, void **valptr)
{
	pthread_t self;
	char *name;
	int num;

	self = pthread__self();
	SDPRINTF(("(pthread_join %p) Joining %p.\n", self, thread));

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

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

	if (thread == self)
		return EDEADLK;

	pthread_spinlock(self, &thread->pt_flaglock);

	if (thread->pt_flags & PT_FLAG_DETACHED) {
		pthread_spinunlock(self, &thread->pt_flaglock);
		return EINVAL;
	}

	num = thread->pt_num;
	pthread_spinlock(self, &thread->pt_join_lock);
	while (thread->pt_state != PT_STATE_ZOMBIE) {
		if ((thread->pt_state == PT_STATE_DEAD) ||
		    (thread->pt_flags & PT_FLAG_DETACHED) ||
		    (thread->pt_num != num)) {
			/*
			 * Another thread beat us to the join, or called
			 * pthread_detach(). If num didn't match, the
			 * thread died and was recycled before we got
			 * another chance to run.
			 */
			pthread_spinunlock(self, &thread->pt_join_lock);
			pthread_spinunlock(self, &thread->pt_flaglock);
			return ESRCH;
		}
		/*
		 * "I'm not dead yet!"
		 * "You will be soon enough."
		 */
		pthread_spinunlock(self, &thread->pt_flaglock);
		pthread_spinlock(self, &self->pt_statelock);
		if (self->pt_cancel) {
			pthread_spinunlock(self, &self->pt_statelock);
			pthread_spinunlock(self, &thread->pt_join_lock);
			pthread_exit(PTHREAD_CANCELED);
		}
		self->pt_state = PT_STATE_BLOCKED_QUEUE;
		self->pt_sleepobj = thread;
		self->pt_sleepq = &thread->pt_joiners;
		self->pt_sleeplock = &thread->pt_join_lock;
		pthread_spinunlock(self, &self->pt_statelock);

		PTQ_INSERT_TAIL(&thread->pt_joiners, self, pt_sleep);
		pthread__block(self, &thread->pt_join_lock);
		pthread_spinlock(self, &thread->pt_flaglock);
		pthread_spinlock(self, &thread->pt_join_lock);
	}

	/* All ours. */
	thread->pt_state = PT_STATE_DEAD;
	name = thread->pt_name;
	thread->pt_name = NULL;
	pthread_spinunlock(self, &thread->pt_join_lock);
	pthread_spinunlock(self, &thread->pt_flaglock);

	if (valptr != NULL)
		*valptr = thread->pt_exitval;

	SDPRINTF(("(pthread_join %p) Joined %p.\n", self, thread));

	/* Cleanup time. Move the dead thread from allqueue to the deadqueue */
	pthread_spinlock(self, &pthread__allqueue_lock);
	PTQ_REMOVE(&pthread__allqueue, thread, pt_allq);
	pthread_spinunlock(self, &pthread__allqueue_lock);

	pthread_spinlock(self, &pthread__deadqueue_lock);
	PTQ_INSERT_HEAD(&pthread__deadqueue, thread, pt_allq);
	pthread_spinunlock(self, &pthread__deadqueue_lock);

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

	return 0;
}


int
pthread_equal(pthread_t t1, pthread_t t2)
{

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


int
pthread_detach(pthread_t thread)
{
	pthread_t self;

	self = pthread__self();

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

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

	pthread_spinlock(self, &thread->pt_flaglock);
	pthread_spinlock(self, &thread->pt_join_lock);

	if (thread->pt_flags & PT_FLAG_DETACHED) {
		pthread_spinunlock(self, &thread->pt_join_lock);
		pthread_spinunlock(self, &thread->pt_flaglock);
		return EINVAL;
	}

	thread->pt_flags |= PT_FLAG_DETACHED;

	/* Any joiners have to be punted now. */
	pthread__sched_sleepers(self, &thread->pt_joiners);

	pthread_spinunlock(self, &thread->pt_join_lock);
	pthread_spinunlock(self, &thread->pt_flaglock);

	return 0;
}


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

	self = pthread__self();

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

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

	pthread_spinlock(self, &thread->pt_join_lock);
	if (thread->pt_name == NULL)
		name[0] = '\0';
	else
		strlcpy(name, thread->pt_name, len);
	pthread_spinunlock(self, &thread->pt_join_lock);

	return 0;
}


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

	if (pthread__find(self, 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_spinlock(self, &thread->pt_join_lock);

	if (thread->pt_state == PT_STATE_DEAD) {
		pthread_spinunlock(self, &thread->pt_join_lock);
		free(cp);
		return EINVAL;
	}

	oldname = thread->pt_name;
	thread->pt_name = cp;

	pthread_spinunlock(self, &thread->pt_join_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)
{
	pthread_t self;

	if (!(thread->pt_state == PT_STATE_RUNNING ||
	    thread->pt_state == PT_STATE_RUNNABLE ||
	    thread->pt_state == PT_STATE_BLOCKED_QUEUE ||
	    thread->pt_state == PT_STATE_BLOCKED_SYS))
		return ESRCH;

	self = pthread__self();

	pthread_spinlock(self, &thread->pt_flaglock);
	thread->pt_flags |= PT_FLAG_CS_PENDING;
	if ((thread->pt_flags & PT_FLAG_CS_DISABLED) == 0) {
		thread->pt_cancel = 1;
		pthread_spinunlock(self, &thread->pt_flaglock);
		pthread_spinlock(self, &thread->pt_statelock);
		if (thread->pt_state == PT_STATE_BLOCKED_SYS) {
			/*
			 * It's sleeping in the kernel. If we can wake
			 * it up, it will notice the cancellation when
			 * it returns. If it doesn't wake up when we
			 * make this call, then it's blocked
			 * uninterruptably in the kernel, and there's
			 * not much to be done about it.
			 */
			_lwp_wakeup(thread->pt_blockedlwp);
		} else if (thread->pt_state == PT_STATE_BLOCKED_QUEUE) {
			/*
			 * We're blocked somewhere (pthread__block()
			 * was called). Cause it to wake up; it will
			 * check for the cancellation if the routine
			 * is a cancellation point, and loop and reblock
			 * otherwise.
			 */
			pthread_spinlock(self, thread->pt_sleeplock);
			PTQ_REMOVE(thread->pt_sleepq, thread,
			    pt_sleep);
			pthread_spinunlock(self, thread->pt_sleeplock);
			pthread__sched(self, thread);
		} else {
			/*
			 * Nothing. The target thread is running and will
			 * notice at the next deferred cancellation point.
			 */
		}
		pthread_spinunlock(self, &thread->pt_statelock);
	} else
		pthread_spinunlock(self, &thread->pt_flaglock);

	return 0;
}


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

	self = pthread__self();
	retval = 0;

	pthread_spinlock(self, &self->pt_flaglock);
	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_spinunlock(self, &self->pt_flaglock);
				pthread_exit(PTHREAD_CANCELED);
			}
		}
	} else
		retval = EINVAL;

	pthread_spinunlock(self, &self->pt_flaglock);
	return retval;
}


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

	self = pthread__self();
	retval = 0;

	pthread_spinlock(self, &self->pt_flaglock);

	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_spinunlock(self, &self->pt_flaglock);
			pthread_exit(PTHREAD_CANCELED);
		}
	} else if (type == PTHREAD_CANCEL_DEFERRED)
		self->pt_flags &= ~PT_FLAG_CS_ASYNC;
	else
		retval = EINVAL;

	pthread_spinunlock(self, &self->pt_flaglock);
	return retval;
}


void
pthread_testcancel()
{
	pthread_t self;

	self = pthread__self();
	if (self->pt_cancel)
		pthread_exit(PTHREAD_CANCELED);
}


/*
 * 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 self, pthread_t id)
{
	pthread_t target;

	pthread_spinlock(self, &pthread__allqueue_lock);
	PTQ_FOREACH(target, &pthread__allqueue, pt_allq)
	    if (target == id)
		    break;
	pthread_spinunlock(self, &pthread__allqueue_lock);

	if (target == NULL)
		return ESRCH;

	return 0;
}


void
pthread__testcancel(pthread_t self)
{

	if (self->pt_cancel)
		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(char *file, int line, char *function, 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(char *file, int line, char *function, 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);
	}
}