130 lines
4.0 KiB
C
130 lines
4.0 KiB
C
/*-
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* Copyright (c) 2004 Michael Telahun Makonnen <mtm@FreeBSD.Org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <pthread.h>
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#include <stdlib.h>
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#include <string.h>
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#include "thr_private.h"
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__weak_reference(_pthread_barrier_destroy, pthread_barrier_destroy);
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__weak_reference(_pthread_barrier_init, pthread_barrier_init);
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__weak_reference(_pthread_barrier_wait, pthread_barrier_wait);
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int
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_pthread_barrier_destroy(pthread_barrier_t *barrier)
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{
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if (*barrier == NULL)
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return (EINVAL);
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if ((*barrier)->b_subtotal > 0)
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return (EBUSY);
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PTHREAD_ASSERT((*barrier)->b_subtotal == 0,
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"barrier count must be zero when destroyed");
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free(*barrier);
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*barrier = NULL;
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return (0);
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}
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int
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_pthread_barrier_init(pthread_barrier_t *barrier,
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const pthread_barrierattr_t attr, unsigned int count)
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{
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if (count < 1)
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return (EINVAL);
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*barrier =
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(struct pthread_barrier *)malloc(sizeof(struct pthread_barrier));
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if (*barrier == NULL)
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return (ENOMEM);
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memset((void *)*barrier, 0, sizeof(struct pthread_barrier));
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(*barrier)->b_total = count;
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TAILQ_INIT(&(*barrier)->b_barrq);
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return (0);
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}
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int
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_pthread_barrier_wait(pthread_barrier_t *barrier)
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{
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struct pthread_barrier *b;
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struct pthread *ptd;
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int error;
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if (*barrier == NULL)
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return (EINVAL);
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/*
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* Check if threads waiting on the barrier can be released. If
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* so, release them and make this last thread the special thread.
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*/
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error = 0;
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b = *barrier;
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UMTX_LOCK(&b->b_lock);
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if (b->b_subtotal == (b->b_total - 1)) {
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TAILQ_FOREACH(ptd, &b->b_barrq, sqe) {
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_thread_critical_enter(ptd);
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PTHREAD_NEW_STATE(ptd, PS_RUNNING);
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TAILQ_REMOVE(&b->b_barrq, ptd, sqe);
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ptd->flags |= PTHREAD_FLAGS_BARR_REL;
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_thread_critical_exit(ptd);
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}
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b->b_subtotal = 0;
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UMTX_UNLOCK(&b->b_lock);
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return (PTHREAD_BARRIER_SERIAL_THREAD);
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}
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/*
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* More threads need to reach the barrier. Suspend this thread.
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*/
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_thread_critical_enter(curthread);
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TAILQ_INSERT_HEAD(&b->b_barrq, curthread, sqe);
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PTHREAD_NEW_STATE(curthread, PS_BARRIER_WAIT);
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_thread_critical_exit(curthread);
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b->b_subtotal++;
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PTHREAD_ASSERT(b->b_subtotal < b->b_total,
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"the number of threads waiting at a barrier is too large");
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UMTX_UNLOCK(&b->b_lock);
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do {
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error = _thread_suspend(curthread, NULL);
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if (error == EINTR) {
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/*
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* Make sure this thread wasn't released from
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* the barrier while it was handling the signal.
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*/
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_thread_critical_enter(curthread);
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if ((curthread->flags & PTHREAD_FLAGS_BARR_REL) != 0) {
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curthread->flags &= ~PTHREAD_FLAGS_BARR_REL;
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_thread_critical_exit(curthread);
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error = 0;
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break;
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}
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PTHREAD_NEW_STATE(curthread, PS_BARRIER_WAIT);
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_thread_critical_exit(curthread);
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}
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} while (error == EINTR);
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return (error);
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}
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