Implement PThreads barriers and barrier attributes.

6 files changed, 236 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