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  */
  29
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <unistd.h>
  33 #include <sys/time.h>
  34
  35 #include "thr_private.h"
  36
  37 /*
  38  * This function is used to acquire a contested lock.
  39  */
  40 int
  41 __thr_umtx_lock(volatile umtx_t *mtx, int timo)
  42 {
  43         int v, errval, ret = 0;
  44
  45         /* contested */
  46         do {
  47                 v = *mtx;
  48                 if (v == 2 || atomic_cmpset_acq_int(mtx, 1, 2)) {
  49                         if (timo == 0)
  50                                 _umtx_sleep_err(mtx, 2, timo);
  51                         else if ( (errval = _umtx_sleep_err(mtx, 2, timo)) > 0) {
  52                                 if (errval == EAGAIN) {
  53                                         if (atomic_cmpset_acq_int(mtx, 0, 2))
  54                                                 ret = 0;
  55                                         else
  56                                                 ret = ETIMEDOUT;
  57                                         break;
  58                                 }
  59                         }
  60                 }
  61         } while (!atomic_cmpset_acq_int(mtx, 0, 2));
  62
  63         return (ret);
  64 }
  65
  66 void
  67 __thr_umtx_unlock(volatile umtx_t *mtx)
  68 {
  69         int v;
  70
  71         for (;;) {
  72                 v = *mtx;
  73                 if (atomic_cmpset_acq_int(mtx, v, v-1)) {
  74                         if (v != 1) {
  75                                 *mtx = 0;
  76                                 _umtx_wakeup_err(mtx, 1);
  77                         }
  78                         break;
  79                 }
  80         }
  81 }
  82
  83 /*
  84  * Low level timed umtx lock.  This function must never return
  85  * EINTR.
  86  */
  87 int
  88 __thr_umtx_timedlock(volatile umtx_t *mtx, const struct timespec *timeout)
  89 {
  90         struct timespec ts, ts2, ts3;
  91         int timo, ret;
  92
  93         if ((timeout->tv_sec < 0) ||
  94             (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
  95         return (ETIMEDOUT);
  96
  97         /* XXX there should have MONO timer! */
  98         clock_gettime(CLOCK_REALTIME, &ts);
  99         TIMESPEC_ADD(&ts, &ts, timeout);
 100         ts2 = *timeout;
 101
 102         for (;;) {
 103                 if (ts2.tv_nsec) {
 104                         timo = (int)(ts2.tv_nsec / 1000);
 105                         if (timo == 0)
 106                                 timo = 1;
 107                 } else {
 108                         timo = 1000000;
 109                 }
 110                 ret = __thr_umtx_lock(mtx, timo);
 111                 if (ret != EINTR && ret != ETIMEDOUT)
 112                         break;
 113                 clock_gettime(CLOCK_REALTIME, &ts3);
 114                 TIMESPEC_SUB(&ts2, &ts, &ts3);
 115                 if (ts2.tv_sec < 0 ||
 116                     (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
 117                         ret = ETIMEDOUT;
 118                 break;
 119                 }
 120         }
 121         return (ret);
 122 }
 123
 124 int
 125 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout,
 126                int clockid)
 127 {
 128         struct timespec ts, ts2, ts3;
 129         int timo, errval, ret = 0;
 130
 131         if (*mtx != exp)
 132                 return (0);
 133
 134         if (timeout == NULL) {
 135                 while ( (errval = _umtx_sleep_err(mtx, exp, 10000000)) > 0) {
 136                         if (errval == EBUSY)
 137                                 break;
 138                         if (errval == EINTR) {
 139                                 ret = EINTR;
 140                         break;
 141                         }
 142 #if 0
 143                         if (errval == ETIMEDOUT || errval == EWOULDBLOCK) {
 144                                 if (*mtx != exp) {
 145                                         fprintf(stderr,
 146                                             "thr_umtx_wait: FAULT VALUE CHANGE "
 147                                             "%d -> %d oncond %p\n",
 148                                             exp, *mtx, mtx);
 149                                 }
 150                         }
 151 #endif
 152                         if (*mtx != exp)
 153                                 return(0);
 154                 }
 155                 return (ret);
 156         }
 157
 158         if ((timeout->tv_sec < 0) ||
 159             (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
 160         return (ETIMEDOUT);
 161
 162         clock_gettime(clockid, &ts);
 163         TIMESPEC_ADD(&ts, &ts, timeout);
 164         ts2 = *timeout;
 165
 166         for (;;) {
 167                 if (ts2.tv_nsec) {
 168                         timo = (int)(ts2.tv_nsec / 1000);
 169                         if (timo == 0)
 170                                 timo = 1;
 171                 } else {
 172                         timo = 1000000;
 173                 }
 174
 175                 if ( (errval = _umtx_sleep_err(mtx, exp, timo)) > 0) {
 176                         if (errval == EBUSY) {
 177                                 ret = 0;
 178                                 break;
 179                         } else if (errval == EINTR) {
 180                                 ret = EINTR;
 181                                 break;
 182                         }
 183                 }
 184
 185                 clock_gettime(clockid, &ts3);
 186                 TIMESPEC_SUB(&ts2, &ts, &ts3);
 187                 if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
 188                         ret = ETIMEDOUT;
 189                         break;
 190                 }
 191         }
 192         return (ret);
 193 }
 194
 195 void
 196 _thr_umtx_wake(volatile umtx_t *mtx, int count)
 197 {
 198         _umtx_wakeup_err(mtx, count);
 199 }