Implement PThreads barriers and barrier attributes.

9 files changed, 551 insertions, 1 deletions

diff --git a/lib/libthr/thread/Makefile.inc b/lib/libthr/thread/Makefile.inc
index c43737e..8e11911 100644
--- a/lib/libthr/thread/Makefile.inc
+++ b/lib/libthr/thread/Makefile.inc
@@ -6,6 +6,8 @@
 SRCS+= \
 	thr_attr.c \
 	thr_autoinit.c \
+	thr_barrier.c \
+	thr_barrierattr.c \
 	thr_cancel.c \
 	thr_clean.c \
 	thr_concurrency.c \
diff --git a/lib/libthr/thread/thr_barrier.c b/lib/libthr/thread/thr_barrier.c
new file mode 100644
index 0000000..c635820
--- /dev/null
+++ b/lib/libthr/thread/thr_barrier.c
@@ -0,0 +1,129 @@
+/*-
+ * Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "thr_private.h"
+
+__weak_reference(_pthread_barrier_destroy, pthread_barrier_destroy);
+__weak_reference(_pthread_barrier_init, pthread_barrier_init);
+__weak_reference(_pthread_barrier_wait, pthread_barrier_wait);
+
+int
+_pthread_barrier_destroy(pthread_barrier_t *barrier)
+{
+	if (*barrier == NULL)
+		return (EINVAL);
+	if ((*barrier)->b_subtotal > 0)
+		return (EBUSY);
+	PTHREAD_ASSERT((*barrier)->b_subtotal == 0,
+	    "barrier count must be zero when destroyed");
+	free(*barrier);
+	*barrier = NULL;
+	return (0);
+}
+
+int
+_pthread_barrier_init(pthread_barrier_t *barrier,
+    const pthread_barrierattr_t attr, unsigned int count)
+{
+	if (count < 1)
+		return (EINVAL);
+	*barrier =
+	    (struct pthread_barrier *)malloc(sizeof(struct pthread_barrier));
+	if (*barrier == NULL)
+		return (ENOMEM);
+	memset((void *)*barrier, 0, sizeof(struct pthread_barrier));
+	(*barrier)->b_total = count;
+	TAILQ_INIT(&(*barrier)->b_barrq);
+	return (0);
+}
+
+int
+_pthread_barrier_wait(pthread_barrier_t *barrier)
+{
+	struct pthread_barrier *b;
+	struct pthread	       *ptd;
+	int error;
+
+	if (*barrier == NULL)
+		return (EINVAL);
+
+	/*
+	 * Check if threads waiting on the barrier can be released. If
+	 * so, release them and make this last thread the special thread.
+	 */
+	error = 0;
+	b = *barrier;
+	UMTX_LOCK(&b->b_lock);
+	if (b->b_subtotal == (b->b_total - 1)) {
+		TAILQ_FOREACH(ptd, &b->b_barrq, sqe) {
+			_thread_critical_enter(ptd);
+			PTHREAD_NEW_STATE(ptd, PS_RUNNING);
+			TAILQ_REMOVE(&b->b_barrq, ptd, sqe);
+			ptd->flags |= PTHREAD_FLAGS_BARR_REL;
+			_thread_critical_exit(ptd);
+		}
+		b->b_subtotal = 0;
+		UMTX_UNLOCK(&b->b_lock);
+		return (PTHREAD_BARRIER_SERIAL_THREAD);
+	}
+
+	/*
+	 * More threads need to reach the barrier. Suspend this thread.
+	 */
+	_thread_critical_enter(curthread);
+	TAILQ_INSERT_HEAD(&b->b_barrq, curthread, sqe);
+	PTHREAD_NEW_STATE(curthread, PS_BARRIER_WAIT);
+	_thread_critical_exit(curthread);
+	b->b_subtotal++;
+	PTHREAD_ASSERT(b->b_subtotal < b->b_total,
+	    "the number of threads waiting at a barrier is too large");
+	UMTX_UNLOCK(&b->b_lock);
+	do {
+		error = _thread_suspend(curthread, NULL);
+		if (error == EINTR) {
+			/*
+			 * Make sure this thread wasn't released from
+			 * the barrier while it was handling the signal.
+			 */
+			_thread_critical_enter(curthread);
+			if ((curthread->flags & PTHREAD_FLAGS_BARR_REL) != 0) {
+				curthread->flags &= ~PTHREAD_FLAGS_BARR_REL;
+				_thread_critical_exit(curthread);
+				error = 0;
+				break;
+			}
+			PTHREAD_NEW_STATE(curthread, PS_BARRIER_WAIT);
+			_thread_critical_exit(curthread);
+		}
+	} while (error == EINTR);
+	return (error);
+}
diff --git a/lib/libthr/thread/thr_barrierattr.c b/lib/libthr/thread/thr_barrierattr.c
new file mode 100644
index 0000000..2fe3955
--- /dev/null
+++ b/lib/libthr/thread/thr_barrierattr.c
@@ -0,0 +1,79 @@
+/*-
+ * Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <pthread.h>
+#include <stdlib.h>
+
+#include "thr_private.h"
+
+__weak_reference(_pthread_barrierattr_destroy, pthread_barrierattr_destroy);
+__weak_reference(_pthread_barrierattr_init, pthread_barrierattr_init);
+__weak_reference(_pthread_barrierattr_getpshared,
+    pthread_barrierattr_getpshared);
+__weak_reference(_pthread_barrierattr_setpshared,
+    pthread_barrierattr_setpshared);
+
+int
+_pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
+{
+	if (*attr == NULL)
+		return (EINVAL);
+	free(*attr);
+	*attr = NULL;
+	return (0);
+}
+
+int
+_pthread_barrierattr_init(pthread_barrierattr_t *attr)
+{
+	*attr =
+	    (pthread_barrierattr_t)malloc(sizeof(struct pthread_barrierattr));
+	if ((*attr) == NULL)
+		return (ENOMEM);
+	(*attr)->ba_pshared = PTHREAD_PROCESS_PRIVATE;
+	return (0);
+}
+
+int
+_pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr, int *pshared)
+{
+	if (*attr == NULL)
+		return (EINVAL);
+	*pshared = (*attr)->ba_pshared;
+	return (0);
+}
+
+int
+_pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
+{
+	if (*attr == NULL || (pshared != PTHREAD_PROCESS_PRIVATE &&
+	    pshared != PTHREAD_PROCESS_SHARED))
+		return (EINVAL);
+	(*attr)->ba_pshared = pshared;
+	return (0);
+}
diff --git a/lib/libthr/thread/thr_cancel.c b/lib/libthr/thread/thr_cancel.c
index d27b4b3..a539de7 100644
--- a/lib/libthr/thread/thr_cancel.c
+++ b/lib/libthr/thread/thr_cancel.c
@@ -93,6 +93,7 @@ retry:
 			PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 			break;
 
+		case PS_BARRIER_WAIT:
 		case PS_MUTEX_WAIT:
 		case PS_COND_WAIT:
 			/*
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index cad1d04..e42bb14 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -146,7 +146,6 @@
 	PTHREAD_SET_STATE(thrd, newstate);				\
 } while (0)
 
-
 /*
  * TailQ initialization values.
  */
@@ -368,6 +367,22 @@ extern int _pthread_page_size;
  */
 #define	GET_CURRENT_TOD(tv)	gettimeofday(&(tv), NULL)
 
+struct pthread_barrierattr {
+	int ba_pshared;
+};
+
+/*
+ * POSIX Threads barrier object.
+ * Lock order:
+ *	1. pthread_barrier
+ *	2. pthread
+ */
+struct pthread_barrier {
+	TAILQ_HEAD(barrq_head, pthread) b_barrq;
+	struct umtx b_lock;
+	int	    b_total;
+	int	    b_subtotal;
+};
 
 struct pthread_rwlockattr {
 	int		pshared;
@@ -388,6 +403,7 @@ enum pthread_state {
 	PS_RUNNING,
 	PS_MUTEX_WAIT,
 	PS_COND_WAIT,
+	PS_BARRIER_WAIT,
 	PS_SLEEP_WAIT,	/* XXX We need to wrap syscalls to set this state */
 	PS_WAIT_WAIT,
 	PS_JOIN,
@@ -535,6 +551,7 @@ struct pthread {
 	int		flags;
 #define PTHREAD_FLAGS_PRIVATE	0x0001
 #define PTHREAD_EXITING		0x0002
+#define PTHREAD_FLAGS_BARR_REL	0x0004	/* has been released from barrier */
 #define PTHREAD_FLAGS_IN_CONDQ	0x0080	/* in condition queue using sqe link*/
 #define PTHREAD_FLAGS_IN_MUTEXQ	0x0100	/* in mutex queue using sqe link */
 #define	PTHREAD_FLAGS_SUSPENDED	0x0200	/* thread is suspended */
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index 0b8ba2b..771afbc 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -130,6 +130,13 @@ _thread_sig_wrapper(int sig, siginfo_t *info, void *context)
 	 * after cleanup handling.
 	 */
 	switch (curthread->state) {
+	case PS_BARRIER_WAIT:
+		/*
+		 * XXX - The thread has reached the barrier. We can't
+		 *	 "back it away" from the barrier.
+		 */
+		_thread_critical_enter(curthread);
+		break;
 	case PS_COND_WAIT:
 		/*
 		 * Cache the address, since it will not be available
diff --git a/share/man/man3/Makefile b/share/man/man3/Makefile
index 8e5df1b..fb9ceb8 100644
--- a/share/man/man3/Makefile
+++ b/share/man/man3/Makefile
@@ -140,6 +140,8 @@ PTHREAD_MAN=	pthread.3 \
 		pthread_attr.3 \
 		pthread_attr_get_np.3 \
 		pthread_attr_setcreatesuspend_np.3 \
+		pthread_barrier_destroy.3 \
+		pthread_barrierattr.3 \
 		pthread_cancel.3 \
 		pthread_cleanup_pop.3 \
 		pthread_cleanup_push.3 \
@@ -216,6 +218,12 @@ PTHREAD_MLINKS=	pthread_attr.3 pthread_attr_destroy.3 \
 		pthread_attr.3 pthread_attr_setstack.3 \
 		pthread_attr.3 pthread_attr_setstackaddr.3 \
 		pthread_attr.3 pthread_attr_setstacksize.3
+PTHREAD_MLINKS+=pthread_barrier_destroy.3 pthread_barrier_init.3 \
+		pthread_barrier_destroy.3 pthread_barrier_wait.3
+PTHREAD_MLINKS+=pthread_barrierattr.3 pthread_barrierattr_destroy.3 \
+		pthread_barrierattr.3 pthread_barrierattr_getpshared.3 \
+		pthread_barrierattr.3 pthread_barrierattr_init.3 \
+		pthread_barrierattr.3 pthread_barrierattr_setpshared.3
 PTHREAD_MLINKS+=pthread_condattr.3 pthread_condattr_destroy.3 \
 		pthread_condattr.3 pthread_condattr_init.3
 PTHREAD_MLINKS+=pthread_getconcurrency.3 pthread_setconcurrency.3
diff --git a/share/man/man3/pthread_barrier_destroy.3 b/share/man/man3/pthread_barrier_destroy.3
new file mode 100644
index 0000000..27ded5b
--- /dev/null
+++ b/share/man/man3/pthread_barrier_destroy.3
@@ -0,0 +1,157 @@
+.\" Copyright (c) 2004 Michael Telahun Makonnen
+.\" All rights reserved.
+.\"
+.\" 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.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+.\"
+.\" $FreeBSD$
+.\"
+.\" Note: The date here should be updated whenever a non-trivial
+.\" change is made to the manual page.
+.Dd February 19, 2004
+.Dt PTHREAD_BARRIER_DESTROY 3 PTHREAD_BARRIER_INIT 3 PTHREAD_BARRIER_WAIT 3
+.Os
+.Sh NAME
+.Nm pthread_barrier_destroy pthread_barrier_init pthread_barrier_wait
+.Nd "destroy, initialize or wait on a barrier object"
+.Sh LIBRARY
+.Lb libpthread
+.Lb libthr
+.Sh SYNOPSIS
+.In pthread.h
+.Ft int
+.Fn pthread_barrier_destroy "pthread_barrier_t *barrier"
+.Ft int
+.Fn pthread_barrier_init "pthread_barrier_t *barrier" "const pthread_barrierattr_t *attr" "int count"
+.Ft int
+.Fn pthread_barrier_wait "pthread_barrier_t *barrier"
+.Sh DESCRIPTION
+The
+.Fn pthread_barrier_init
+function will initialize
+.Fa barrier
+with attributes specified in
+.Fa attr ,
+or if it is NULL,
+with default attributes.
+The number of threads that must call
+.Fn pthread_barrier_wait
+before any of the waiting threads can be
+released is specified by
+.Fa count .
+The
+.Fn pthread_barrier_destroy
+function will destroy
+.Fa barrier
+and release any resources that may have been allocated on its behalf.
+.Pp
+The
+.Fn pthread_barrier_wait
+function will synchronize calling threads at
+.Fa barrier .
+The threads will be blocked from
+making further progress until
+a sufficient number of threads calls this function.
+The number of threads that must call it before
+any of them will be released is determined by the
+.Fa count
+argument to
+.Fn pthread_barrier_init .
+Once the threads have been released the barrier will be reset.
+.Sh DIAGNOSTICS
+If successful,
+both
+.Fn pthread_barrier_destroy
+and
+.Fn pthread_barrier_init
+will return zero.
+Otherwise an error number will be returned to indicate the error.
+If the call to
+.Fn pthread_barrier_wait
+is successful all but one of the threads will return zero.
+That one thread will return PTHREAD_BARRIER_SERIAL_THREAD.
+Otherwise an error number will be returned to indicate the error.
+.Pp
+None of these functions will return EINTR.
+.Sh IMPLIMENTATION NOTES
+In both
+.Lb libpthread
+and
+.Lb libthr
+the PTHREAD_BARRIER_SERIAL_THREAD return value will
+always be returned by the last thread to reach the barrier.
+.Sh ERRORS
+The
+.Fn pthread_barrier_destroy
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EBUSY
+An attempt was made to destroy
+.Fa barrier
+while it was in use.
+.El
+.Pp
+The
+.Fn pthread_barrier_destroy
+and
+.Fn pthread_barrier_wait
+functions may fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The value specified by
+.Fa barrier
+is invalid.
+.El
+.Pp
+The
+.Fn pthread_barrier_init
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EAGAIN
+The system lacks resources,
+other than memory,
+to initialize
+.Fa barrier .
+.It Bq Er EINVAL
+The
+.Fa count
+argument is less than 1.
+.It Bq Er ENOMEM
+Insufficient memory to initialize
+.Fa barrier .
+.El
+.Sh SEE ALSO
+.Xr pthread_barrier_wait 3 ,
+.Xr pthread_barrierattr 3
+.Sh HISTORY
+The
+.Fn pthread_barrier_destroy ,
+.Fn pthread_barrier_init
+and
+.Fn pthread_barrier_wait
+functions first appeared in
+.Lb libpthread
+in
+.Fx 5.2 ,
+and in
+.Lb libthr
+in
+.Fx 5.3 .
diff --git a/share/man/man3/pthread_barrierattr.3 b/share/man/man3/pthread_barrierattr.3
new file mode 100644
index 0000000..2931bdf
--- /dev/null
+++ b/share/man/man3/pthread_barrierattr.3
@@ -0,0 +1,150 @@
+.\" Copyright (c) 2004 Michael Telahun Makonnen
+.\" All rights reserved.
+.\"
+.\" 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.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+.\"
+.\" $FreeBSD$
+.\"
+.\" Note: The date here should be updated whenever a non-trivial
+.\" change is made to the manual page.
+.Dd February 19, 2004
+.Dt PTHREAD_BARRIERATTR_DESTROY 3 PTHREAD_BARRIERATTR_GETPSHARED 3 PTHREAD_BARRIERATTR_INIT 3 PTHREAD_BARRIERATTR_SETPSHARED 3
+.Os
+.Sh NAME
+.Nm pthread_barrierattr_destroy pthread_barrierattr_getpshared
+.Nm pthread_barrierattr_init pthread_barrierattr_setpshared
+.Nd "manipulate a barrier attribute object"
+.Sh LIBRARY
+.Lb libpthread
+.Lb libthr
+.Sh SYNOPSIS
+.In pthread.h
+.Ft int
+.Fn pthread_barrierattr_destroy "pthread_barrierattr_t *attr"
+.Ft int
+.Fn pthread_barrierattr_getpshared "const pthread_barrierattr_t *attr" "int *pshared"
+.Ft int
+.Fn pthread_barrierattr_init "pthread_barrierattr_t *attr"
+.Ft int
+.Fn pthread_barrierattr_setpshared "pthread_barrierattr_t *attr" "int pshared"
+.Sh DESCRIPTION
+The
+.Fn pthread_barrierattr_init
+function will initialize
+.Fa attr
+with default attributes.
+The
+.Fn pthread_barrierattr_destroy
+function will destroy
+.Fa attr
+and release any resources that may have been allocated on its behalf.
+.Pp
+The
+.Fn pthread_barrierattr_getpshared
+function will put the value of the process-shared attribute from
+.Fa attr
+into the memory area pointed to by
+.Fa pshared .
+The
+.Fn pthread_barrierattr_setpshared
+function will set the process-shared attribute of
+.Fa attr
+to the value specified in
+.Fa pshared.
+The argument
+.Fa pshared
+may have one of the following values:
+.Bl -tag -width ".Dv PTHREAD_PROCESS_PRIVATE"
+.It Dv PTHREAD_PROCESS_PRIVATE
+The barrier object it is attached to may only be accessed by
+threads in the same process as the one that created the object.
+.It Dv PTHREAD_PROCESS_SHARED
+The barrier object it is attached to may be accessed by
+threads in processes other than the one that created the object.
+.El
+.Sh DIAGNOSTICS
+If successful all these functions will return zero.
+Otherwise an error number will be returned to indicate the error.
+.Pp
+None of these functions will return EINTR.
+.Pp
+.Sh ERRORS
+The
+.Fn pthread_barrierattr_destroy ,
+.Fn pthread_barrierattr_getpshared
+and
+.Fn pthread_barrierattr_setpshared
+functions may fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The value specified by
+.Fa attr
+is invalid.
+.El
+.Pp
+The
+.Fn pthread_barrierattr_init
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er ENOMEM
+Insufficient memory to initialize the barrier attribute object
+.Fa attr .
+.El
+.Pp
+The
+.Fn pthread_barrierattr_setpshared
+function will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The value specified in
+.Fa pshared
+is not one of the allowed values.
+.El
+.Sh SEE ALSO
+.Xr pthread_barrier_destroy 3 ,
+.Xr pthread_barrier_init 3 ,
+.Xr pthread_barrier_wait 3 ,
+.Sh HISTORY
+The
+.Fn pthread_barrierattr
+functions first appeared in
+.Lb libpthread
+in
+.Fx 5.2 ,
+and in
+.Lb libthr
+in
+.Fx 5.3 .
+.Sh BUGS
+The implementation of
+.Fn pthread_barriers
+does not fully conform to
+.St -p1003.2
+because the process-shared attribute is ignored in
+.Lb libthr ,
+and in
+.Lb libpthread
+if any value other than
+.Dv PTHREAD_PROCESSES_PRIVATE
+is specified in a call to
+.Fn pthread_barrierattr_setpshared
+it will return EINVAL.