lib/libthread_xu/thread/thr_sem.c

   1 /*
   2  * Copyright (C) 2005 David Xu <davidxu@freebsd.org>.
   3  * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice(s), this list of conditions and the following disclaimer as
  11  *    the first lines of this file unmodified other than the possible
  12  *    addition of one or more copyright notices.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice(s), this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  21  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
  22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  25  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  26  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  27  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  28  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * $DragonFly: src/lib/libthread_xu/thread/thr_sem.c,v 1.6 2007/06/26 23:30:05 josepht Exp $
  31  */
  32
  33 #include "namespace.h"
  34 #include <machine/tls.h>
  35 #include <sys/semaphore.h>
  36 #include <sys/mman.h>
  37
  38 #include <errno.h>
  39 #include <fcntl.h>
  40 #include <pthread.h>
  41 #include <stdlib.h>
  42 #include <time.h>
  43 #include "un-namespace.h"
  44 #include "thr_private.h"
  45
  46 /*
  47  * Semaphore definitions.
  48  */
  49 struct sem {
  50         u_int32_t               magic;
  51         volatile umtx_t         count;
  52         int                     semid;
  53         int                     unused; /* pad */
  54 };
  55
  56 #define SEM_MAGIC       ((u_int32_t) 0x09fa4012)
  57
  58 #define SEMID_LWP       0
  59 #define SEMID_FORK      1
  60
  61 static inline int
  62 sem_check_validity(sem_t *sem)
  63 {
  64
  65         if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC)) {
  66                 return (0);
  67         } else {
  68                 errno = EINVAL;
  69                 return (-1);
  70         }
  71 }
  72
  73 static sem_t
  74 sem_alloc(unsigned int value, int pshared)
  75 {
  76         sem_t sem;
  77         int semid;
  78
  79         if (value > SEM_VALUE_MAX) {
  80                 errno = EINVAL;
  81                 return (NULL);
  82         }
  83         if (pshared) {
  84                 static __thread sem_t sem_base;
  85                 static __thread int sem_count;
  86
  87                 if (sem_base == NULL) {
  88                         sem_base = mmap(NULL, getpagesize(),
  89                                         PROT_READ | PROT_WRITE,
  90                                         MAP_ANON | MAP_SHARED,
  91                                         -1, 0);
  92                         sem_count = getpagesize() / sizeof(*sem);
  93                 }
  94                 sem = sem_base++;
  95                 if (--sem_count == 0)
  96                         sem_base = NULL;
  97                 semid = SEMID_FORK;
  98         } else {
  99                 sem = malloc(sizeof(struct sem));
 100                 semid = SEMID_LWP;
 101         }
 102         if (sem == NULL) {
 103                 errno = ENOSPC;
 104                 return (NULL);
 105         }
 106         sem->magic = SEM_MAGIC;
 107         sem->count = (u_int32_t)value;
 108         sem->semid = semid;
 109         return (sem);
 110 }
 111
 112 int
 113 _sem_init(sem_t *sem, int pshared, unsigned int value)
 114 {
 115         (*sem) = sem_alloc(value, pshared);
 116         if ((*sem) == NULL)
 117                 return (-1);
 118         return (0);
 119 }
 120
 121 int
 122 _sem_destroy(sem_t *sem)
 123 {
 124         if (sem_check_validity(sem) != 0)
 125                 return (-1);
 126
 127         (*sem)->magic = 0;
 128
 129         switch ((*sem)->semid) {
 130         case SEMID_LWP:
 131                 free(*sem);
 132                 break;
 133         case SEMID_FORK:
 134                 /* memory is left intact */
 135                 break;
 136         }
 137         return (0);
 138 }
 139
 140 int
 141 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
 142 {
 143         if (sem_check_validity(sem) != 0)
 144                 return (-1);
 145
 146         *sval = (*sem)->count;
 147         return (0);
 148 }
 149
 150 int
 151 _sem_trywait(sem_t *sem)
 152 {
 153         int val;
 154
 155         if (sem_check_validity(sem) != 0)
 156                 return (-1);
 157
 158         while ((val = (*sem)->count) > 0) {
 159                 if (atomic_cmpset_int(&(*sem)->count, val, val - 1))
 160                         return (0);
 161         }
 162         errno = EAGAIN;
 163         return (-1);
 164 }
 165
 166 int
 167 _sem_wait(sem_t *sem)
 168 {
 169         struct pthread *curthread;
 170         int val, oldcancel, retval;
 171
 172         if (sem_check_validity(sem) != 0)
 173                 return (-1);
 174
 175         curthread = tls_get_curthread();
 176         _pthread_testcancel();
 177         do {
 178                 while ((val = (*sem)->count) > 0) {
 179                         if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
 180                                 return (0);
 181                 }
 182                 oldcancel = _thr_cancel_enter(curthread);
 183                 retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0);
 184                 _thr_cancel_leave(curthread, oldcancel);
 185         } while (retval == 0);
 186         errno = retval;
 187         return (-1);
 188 }
 189
 190 #if 0
 191 int
 192 _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime)
 193 {
 194         struct timespec ts, ts2;
 195         struct pthread *curthread;
 196         int val, oldcancel, retval;
 197
 198         if (sem_check_validity(sem) != 0)
 199                 return (-1);
 200
 201         curthread = tls_get_curthread();
 202
 203         /*
 204          * The timeout argument is only supposed to
 205          * be checked if the thread would have blocked.
 206          */
 207         _pthread_testcancel();
 208         do {
 209                 while ((val = (*sem)->count) > 0) {
 210                         if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
 211                                 return (0);
 212                 }
 213                 if (abstime == NULL) {
 214                         errno = EINVAL;
 215                         return (-1);
 216                 }
 217                 clock_gettime(CLOCK_REALTIME, &ts);
 218                 TIMESPEC_SUB(&ts2, abstime, &ts);
 219                 oldcancel = _thr_cancel_enter(curthread);
 220                 retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2,
 221                                         CLOCK_REALTIME);
 222                 _thr_cancel_leave(curthread, oldcancel);
 223         } while (retval == 0);
 224         errno = retval;
 225         return (-1);
 226 }
 227 #endif
 228
 229 int
 230 _sem_post(sem_t *sem)
 231 {
 232         int val;
 233
 234         if (sem_check_validity(sem) != 0)
 235                 return (-1);
 236
 237         /*
 238          * sem_post() is required to be safe to call from within
 239          * signal handlers, these code should work as that.
 240          */
 241         do {
 242                 val = (*sem)->count;
 243         } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1));
 244         _thr_umtx_wake(&(*sem)->count, val + 1);
 245         return (0);
 246 }
 247
 248 __strong_reference(_sem_destroy, sem_destroy);
 249 __strong_reference(_sem_getvalue, sem_getvalue);
 250 __strong_reference(_sem_init, sem_init);
 251 __strong_reference(_sem_trywait, sem_trywait);
 252 __strong_reference(_sem_wait, sem_wait);
 253 #if 0
 254 __strong_reference(_sem_timedwait, sem_timedwait);
 255 #endif
 256 __strong_reference(_sem_post, sem_post);
 257