sysdeps/pthread/aio_suspend.c

   1 /* Suspend until termination of a requests.
   2    Copyright (C) 1997-2000,2002,2003,2005,2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21
  22 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  23    implementations of aio_suspend and aio_suspend64 are identical and so
  24    we want to avoid code duplication by using aliases.  But gcc sees
  25    the different parameter lists and prints a warning.  We define here
  26    a function so that aio_suspend64 has no prototype.  */
  27 #define aio_suspend64 XXX
  28 #include <aio.h>
  29 /* And undo the hack.  */
  30 #undef aio_suspend64
  31
  32 #include <assert.h>
  33 #include <errno.h>
  34 #include <stdbool.h>
  35 #include <stdlib.h>
  36 #include <sys/time.h>
  37
  38 #include <bits/libc-lock.h>
  39 #include <aio_misc.h>
  40
  41
  42 struct clparam
  43 {
  44   const struct aiocb *const *list;
  45   struct waitlist *waitlist;
  46   struct requestlist **requestlist;
  47 #ifndef DONT_NEED_AIO_MISC_COND
  48   pthread_cond_t *cond;
  49 #endif
  50   int nent;
  51 };
  52
  53
  54 static void
  55 cleanup (void *arg)
  56 {
  57 #ifdef DONT_NEED_AIO_MISC_COND
  58   /* Acquire the mutex.  If pthread_cond_*wait is used this would
  59      happen implicitly.  */
  60   pthread_mutex_lock (&__aio_requests_mutex);
  61 #endif
  62
  63   const struct clparam *param = (const struct clparam *) arg;
  64
  65   /* Now remove the entry in the waiting list for all requests
  66      which didn't terminate.  */
  67   int cnt = param->nent;
  68   while (cnt-- > 0)
  69     if (param->list[cnt] != NULL
  70         && param->list[cnt]->__error_code == EINPROGRESS)
  71       {
  72         struct waitlist **listp;
  73
  74         assert (param->requestlist[cnt] != NULL);
  75
  76         /* There is the chance that we cannot find our entry anymore. This
  77            could happen if the request terminated and restarted again.  */
  78         listp = &param->requestlist[cnt]->waiting;
  79         while (*listp != NULL && *listp != &param->waitlist[cnt])
  80           listp = &(*listp)->next;
  81
  82         if (*listp != NULL)
  83           *listp = (*listp)->next;
  84       }
  85
  86 #ifndef DONT_NEED_AIO_MISC_COND
  87   /* Release the conditional variable.  */
  88   (void) pthread_cond_destroy (param->cond);
  89 #endif
  90
  91   /* Release the mutex.  */
  92   pthread_mutex_unlock (&__aio_requests_mutex);
  93 }
  94
  95 #ifdef DONT_NEED_AIO_MISC_COND
  96 static int
  97 __attribute__ ((noinline))
  98 do_aio_misc_wait(int *cntr, const struct timespec *timeout)
  99 {
 100         int result = 0;
 101
 102         AIO_MISC_WAIT(result, *cntr, timeout, 1);
 103
 104         return result;
 105 }
 106 #endif
 107
 108 int
 109 aio_suspend (list, nent, timeout)
 110      const struct aiocb *const list[];
 111      int nent;
 112      const struct timespec *timeout;
 113 {
 114   if (__builtin_expect (nent < 0, 0))
 115     {
 116       __set_errno (EINVAL);
 117       return -1;
 118     }
 119
 120   struct waitlist waitlist[nent];
 121   struct requestlist *requestlist[nent];
 122 #ifndef DONT_NEED_AIO_MISC_COND
 123   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 124 #endif
 125   int cnt;
 126   bool any = false;
 127   int result = 0;
 128   int cntr = 1;
 129
 130   /* Request the mutex.  */
 131   pthread_mutex_lock (&__aio_requests_mutex);
 132
 133   /* There is not yet a finished request.  Signal the request that
 134      we are working for it.  */
 135   for (cnt = 0; cnt < nent; ++cnt)
 136     if (list[cnt] != NULL)
 137       {
 138         if (list[cnt]->__error_code == EINPROGRESS)
 139           {
 140             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 141
 142             if (requestlist[cnt] != NULL)
 143               {
 144 #ifndef DONT_NEED_AIO_MISC_COND
 145                 waitlist[cnt].cond = &cond;
 146 #endif
 147                 waitlist[cnt].result = NULL;
 148                 waitlist[cnt].next = requestlist[cnt]->waiting;
 149                 waitlist[cnt].counterp = &cntr;
 150                 waitlist[cnt].sigevp = NULL;
 151 #ifdef BROKEN_THREAD_SIGNALS
 152                 waitlist[cnt].caller_pid = 0;   /* Not needed.  */
 153 #endif
 154                 requestlist[cnt]->waiting = &waitlist[cnt];
 155                 any = true;
 156               }
 157             else
 158               /* We will never suspend.  */
 159               break;
 160           }
 161         else
 162           /* We will never suspend.  */
 163           break;
 164       }
 165
 166
 167   /* Only if none of the entries is NULL or finished to be wait.  */
 168   if (cnt == nent && any)
 169     {
 170       struct clparam clparam =
 171         {
 172           .list = list,
 173           .waitlist = waitlist,
 174           .requestlist = requestlist,
 175 #ifndef DONT_NEED_AIO_MISC_COND
 176           .cond = &cond,
 177 #endif
 178           .nent = nent
 179         };
 180
 181       pthread_cleanup_push (cleanup, &clparam);
 182
 183 #ifdef DONT_NEED_AIO_MISC_COND
 184       result = do_aio_misc_wait(&cntr, timeout);
 185 #else
 186       if (timeout == NULL)
 187         result = pthread_cond_wait (&cond, &__aio_requests_mutex);
 188       else
 189         {
 190           /* We have to convert the relative timeout value into an
 191              absolute time value with pthread_cond_timedwait expects.  */
 192           struct timeval now;
 193           struct timespec abstime;
 194
 195           __gettimeofday (&now, NULL);
 196           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 197           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 198           if (abstime.tv_nsec >= 1000000000)
 199             {
 200               abstime.tv_nsec -= 1000000000;
 201               abstime.tv_sec += 1;
 202             }
 203
 204           result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 205                                            &abstime);
 206         }
 207 #endif
 208
 209       pthread_cleanup_pop (0);
 210     }
 211
 212   /* Now remove the entry in the waiting list for all requests
 213      which didn't terminate.  */
 214   while (cnt-- > 0)
 215     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 216       {
 217         struct waitlist **listp;
 218
 219         assert (requestlist[cnt] != NULL);
 220
 221         /* There is the chance that we cannot find our entry anymore. This
 222            could happen if the request terminated and restarted again.  */
 223         listp = &requestlist[cnt]->waiting;
 224         while (*listp != NULL && *listp != &waitlist[cnt])
 225           listp = &(*listp)->next;
 226
 227         if (*listp != NULL)
 228           *listp = (*listp)->next;
 229       }
 230
 231 #ifndef DONT_NEED_AIO_MISC_COND
 232   /* Release the conditional variable.  */
 233   if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
 234     /* This must never happen.  */
 235     abort ();
 236 #endif
 237
 238   if (result != 0)
 239     {
 240 #ifndef DONT_NEED_AIO_MISC_COND
 241       /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
 242          the timeout error report of `pthread_cond_timedwait' to the
 243          form expected from `aio_suspend'.  */
 244       if (result == ETIMEDOUT)
 245         __set_errno (EAGAIN);
 246       else
 247 #endif
 248         __set_errno (result);
 249
 250       result = -1;
 251     }
 252
 253   /* Release the mutex.  */
 254   pthread_mutex_unlock (&__aio_requests_mutex);
 255
 256   return result;
 257 }
 258
 259 weak_alias (aio_suspend, aio_suspend64)