1 /*- 2 * Copyright (c) 2003 David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/lib/libpthread/thread/thr_barrier.c,v 1.1 2003/09/04 14:06:43 davidxu Exp $ 27 * $DragonFly: src/lib/libthread_xu/thread/thr_barrier.c,v 1.4 2005/03/29 19:26:20 joerg Exp $ 28 */ 29 30 #include <machine/tls.h> 31 32 #include <errno.h> 33 #include <stdlib.h> 34 #include <pthread.h> 35 36 #include "thr_private.h" 37 38 __weak_reference(_pthread_barrier_init, pthread_barrier_init); 39 __weak_reference(_pthread_barrier_wait, pthread_barrier_wait); 40 __weak_reference(_pthread_barrier_destroy, pthread_barrier_destroy); 41 42 int 43 _pthread_barrier_destroy(pthread_barrier_t *barrier) 44 { 45 pthread_barrier_t bar; 46 47 if (barrier == NULL || *barrier == NULL) 48 return (EINVAL); 49 50 bar = *barrier; 51 if (bar->b_waiters > 0) 52 return (EBUSY); 53 *barrier = NULL; 54 free(bar); 55 return (0); 56 } 57 58 int 59 _pthread_barrier_init(pthread_barrier_t *barrier, 60 const pthread_barrierattr_t *attr, int count) 61 { 62 pthread_barrier_t bar; 63 64 if (barrier == NULL || count <= 0) 65 return (EINVAL); 66 67 bar = malloc(sizeof(struct pthread_barrier)); 68 if (bar == NULL) 69 return (ENOMEM); 70 71 _thr_umtx_init(&bar->b_lock); 72 bar->b_cycle = 0; 73 bar->b_waiters = 0; 74 bar->b_count = count; 75 *barrier = bar; 76 77 return (0); 78 } 79 80 int 81 _pthread_barrier_wait(pthread_barrier_t *barrier) 82 { 83 struct pthread *curthread = tls_get_curthread(); 84 pthread_barrier_t bar; 85 long cycle; 86 int ret; 87 88 if (barrier == NULL || *barrier == NULL) 89 return (EINVAL); 90 91 bar = *barrier; 92 THR_UMTX_LOCK(curthread, &bar->b_lock); 93 if (++bar->b_waiters == bar->b_count) { 94 /* Current thread is lastest thread */ 95 bar->b_waiters = 0; 96 bar->b_cycle++; 97 _thr_umtx_wake(&bar->b_cycle, bar->b_count); 98 THR_UMTX_UNLOCK(curthread, &bar->b_lock); 99 ret = PTHREAD_BARRIER_SERIAL_THREAD; 100 } else { 101 cycle = bar->b_cycle; 102 THR_UMTX_UNLOCK(curthread, &bar->b_lock); 103 do { 104 _thr_umtx_wait(&bar->b_cycle, cycle, NULL, 0); 105 /* test cycle to avoid bogus wakeup */ 106 } while (cycle == bar->b_cycle); 107 ret = 0; 108 } 109 return (ret); 110 } 111