lib/libthread_xu/thread/thr_umtx.c

   1 /*-
   2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
   3  * Copyright (c) 2005 Matthew Dillon <dillon@backplane.com>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $DragonFly: src/lib/libthread_xu/thread/thr_umtx.c,v 1.4 2008/04/14 20:12:41 dillon Exp $
  29  */
  30
  31 #include <assert.h>
  32 #include <errno.h>
  33 #include <unistd.h>
  34 #include <sys/time.h>
  35
  36 #include "thr_private.h"
  37
  38 /*
  39  * This function is used to acquire a contested lock.
  40  */
  41 int
  42 __thr_umtx_lock(volatile umtx_t *mtx, int timo)
  43 {
  44         int v, errval, ret = 0;
  45
  46         /* contested */
  47         do {
  48                 v = *mtx;
  49                 if (v == 2 || atomic_cmpset_acq_int(mtx, 1, 2)) {
  50                         if (timo == 0)
  51                                 _umtx_sleep_err(mtx, 2, timo);
  52                         else if ( (errval = _umtx_sleep_err(mtx, 2, timo)) > 0) {
  53                                 if (errval == EAGAIN) {
  54                                         if (atomic_cmpset_acq_int(mtx, 0, 2))
  55                                                 ret = 0;
  56                                         else
  57                                                 ret = ETIMEDOUT;
  58                                         break;
  59                                 }
  60                         }
  61                 }
  62         } while (!atomic_cmpset_acq_int(mtx, 0, 2));
  63
  64         return (ret);
  65 }
  66
  67 void
  68 __thr_umtx_unlock(volatile umtx_t *mtx)
  69 {
  70         int v;
  71
  72         for (;;) {
  73                 v = *mtx;
  74                 if (atomic_cmpset_acq_int(mtx, v, v-1)) {
  75                         if (v != 1) {
  76                                 *mtx = 0;
  77                                 _umtx_wakeup_err(mtx, 1);
  78                         }
  79                         break;
  80                 }
  81         }
  82 }
  83
  84 int
  85 __thr_umtx_timedlock(volatile umtx_t *mtx, const struct timespec *timeout)
  86 {
  87     struct timespec ts, ts2, ts3;
  88     int timo, ret;
  89
  90     if ((timeout->tv_sec < 0) ||
  91         (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
  92         return (ETIMEDOUT);
  93
  94     /* XXX there should have MONO timer! */
  95     clock_gettime(CLOCK_REALTIME, &ts);
  96     TIMESPEC_ADD(&ts, &ts, timeout);
  97     ts2 = *timeout;
  98
  99     for (;;) {
 100         if (ts2.tv_nsec) {
 101             timo = (int)(ts2.tv_nsec / 1000);
 102             if (timo == 0)
 103                 timo = 1;
 104         } else {
 105             timo = 1000000;
 106         }
 107         ret = __thr_umtx_lock(mtx, timo);
 108         if (ret != ETIMEDOUT)
 109             break;
 110         clock_gettime(CLOCK_REALTIME, &ts3);
 111         TIMESPEC_SUB(&ts2, &ts, &ts3);
 112         if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
 113             ret = ETIMEDOUT;
 114             break;
 115         }
 116     }
 117     return (ret);
 118 }
 119
 120 int
 121 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout,
 122                int clockid)
 123 {
 124     struct timespec ts, ts2, ts3;
 125     int timo, errval, ret = 0;
 126
 127     if (*mtx != exp)
 128         return (0);
 129
 130     if (timeout == NULL) {
 131         while ( (errval = _umtx_sleep_err(mtx, exp, 10000000)) > 0) {
 132             if (errval == EBUSY)
 133                 break;
 134             if (errval == EINTR) {
 135                 ret = EINTR;
 136                 break;
 137             }
 138             if (errval == ETIMEDOUT || errval == EWOULDBLOCK) {
 139                 if (*mtx != exp) {
 140                     fprintf(stderr, "thr_umtx_wait: FAULT VALUE CHANGE %d -> %d oncond %p\n", exp, *mtx, mtx);
 141                 }
 142             }
 143             if (*mtx != exp)
 144                 return(0);
 145         }
 146         return (ret);
 147     }
 148
 149     if ((timeout->tv_sec < 0) ||
 150         (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
 151         return (ETIMEDOUT);
 152
 153     clock_gettime(clockid, &ts);
 154     TIMESPEC_ADD(&ts, &ts, timeout);
 155     ts2 = *timeout;
 156
 157     for (;;) {
 158         if (ts2.tv_nsec) {
 159             timo = (int)(ts2.tv_nsec / 1000);
 160             if (timo == 0)
 161                 timo = 1;
 162         } else {
 163             timo = 1000000;
 164         }
 165         if ( (errval = _umtx_sleep_err(mtx, exp, timo)) > 0) {
 166             if (errval == EBUSY) {
 167                 ret = 0;
 168                 break;
 169             } else if (errval == EINTR) {
 170                 ret = EINTR;
 171                 break;
 172             }
 173         }
 174         clock_gettime(clockid, &ts3);
 175         TIMESPEC_SUB(&ts2, &ts, &ts3);
 176         if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
 177             ret = ETIMEDOUT;
 178             break;
 179         }
 180     }
 181     return (ret);
 182 }
 183
 184 void _thr_umtx_wake(volatile umtx_t *mtx, int count)
 185 {
 186     _umtx_wakeup_err(mtx, count);
 187 }