lib/libthr/thread/thr_barrier.c

   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  * $FreeBSD$
  27  */
  28
  29 #include "namespace.h"
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #include <pthread.h>
  33 #include "un-namespace.h"
  34
  35 #include "thr_private.h"
  36
  37 _Static_assert(sizeof(struct pthread_barrier) <= PAGE_SIZE,
  38     "pthread_barrier is too large for off-page");
  39
  40 __weak_reference(_pthread_barrier_init,         pthread_barrier_init);
  41 __weak_reference(_pthread_barrier_wait,         pthread_barrier_wait);
  42 __weak_reference(_pthread_barrier_destroy,      pthread_barrier_destroy);
  43
  44 int
  45 _pthread_barrier_destroy(pthread_barrier_t *barrier)
  46 {
  47         pthread_barrier_t bar;
  48         struct pthread *curthread;
  49         int pshared;
  50
  51         if (barrier == NULL || *barrier == NULL)
  52                 return (EINVAL);
  53
  54         if (*barrier == THR_PSHARED_PTR) {
  55                 bar = __thr_pshared_offpage(barrier, 0);
  56                 if (bar == NULL) {
  57                         *barrier = NULL;
  58                         return (0);
  59                 }
  60                 pshared = 1;
  61         } else {
  62                 bar = *barrier;
  63                 pshared = 0;
  64         }
  65         curthread = _get_curthread();
  66         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
  67         if (bar->b_destroying) {
  68                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  69                 return (EBUSY);
  70         }
  71         bar->b_destroying = 1;
  72         do {
  73                 if (bar->b_waiters > 0) {
  74                         bar->b_destroying = 0;
  75                         THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  76                         return (EBUSY);
  77                 }
  78                 if (bar->b_refcount != 0) {
  79                         _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
  80                         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
  81                 } else
  82                         break;
  83         } while (1);
  84         bar->b_destroying = 0;
  85         THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
  86
  87         *barrier = NULL;
  88         if (pshared)
  89                 __thr_pshared_destroy(barrier);
  90         else
  91                 free(bar);
  92         return (0);
  93 }
  94
  95 int
  96 _pthread_barrier_init(pthread_barrier_t *barrier,
  97     const pthread_barrierattr_t *attr, unsigned count)
  98 {
  99         pthread_barrier_t bar;
 100         int pshared;
 101
 102         if (barrier == NULL || count <= 0)
 103                 return (EINVAL);
 104
 105         if (attr == NULL || *attr == NULL ||
 106             (*attr)->pshared == PTHREAD_PROCESS_PRIVATE) {
 107                 bar = calloc(1, sizeof(struct pthread_barrier));
 108                 if (bar == NULL)
 109                         return (ENOMEM);
 110                 *barrier = bar;
 111                 pshared = 0;
 112         } else {
 113                 bar = __thr_pshared_offpage(barrier, 1);
 114                 if (bar == NULL)
 115                         return (EFAULT);
 116                 *barrier = THR_PSHARED_PTR;
 117                 pshared = 1;
 118         }
 119
 120         _thr_umutex_init(&bar->b_lock);
 121         _thr_ucond_init(&bar->b_cv);
 122         if (pshared) {
 123                 bar->b_lock.m_flags |= USYNC_PROCESS_SHARED;
 124                 bar->b_cv.c_flags |= USYNC_PROCESS_SHARED;
 125         }
 126         bar->b_count = count;
 127         return (0);
 128 }
 129
 130 int
 131 _pthread_barrier_wait(pthread_barrier_t *barrier)
 132 {
 133         struct pthread *curthread;
 134         pthread_barrier_t bar;
 135         int64_t cycle;
 136         int ret;
 137
 138         if (barrier == NULL || *barrier == NULL)
 139                 return (EINVAL);
 140
 141         if (*barrier == THR_PSHARED_PTR) {
 142                 bar = __thr_pshared_offpage(barrier, 0);
 143                 if (bar == NULL)
 144                         return (EINVAL);
 145         } else {
 146                 bar = *barrier;
 147         }
 148         curthread = _get_curthread();
 149         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
 150         if (++bar->b_waiters == bar->b_count) {
 151                 /* Current thread is lastest thread */
 152                 bar->b_waiters = 0;
 153                 bar->b_cycle++;
 154                 _thr_ucond_broadcast(&bar->b_cv);
 155                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
 156                 ret = PTHREAD_BARRIER_SERIAL_THREAD;
 157         } else {
 158                 cycle = bar->b_cycle;
 159                 bar->b_refcount++;
 160                 do {
 161                         _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
 162                         THR_UMUTEX_LOCK(curthread, &bar->b_lock);
 163                         /* test cycle to avoid bogus wakeup */
 164                 } while (cycle == bar->b_cycle);
 165                 if (--bar->b_refcount == 0 && bar->b_destroying)
 166                         _thr_ucond_broadcast(&bar->b_cv);
 167                 THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
 168                 ret = 0;
 169         }
 170         return (ret);
 171 }