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
  96 int
  97 aio_suspend (list, nent, timeout)
  98      const struct aiocb *const list[];
  99      int nent;
 100      const struct timespec *timeout;
 101 {
 102   if (__builtin_expect (nent < 0, 0))
 103     {
 104       __set_errno (EINVAL);
 105       return -1;
 106     }
 107
 108   struct waitlist waitlist[nent];
 109   struct requestlist *requestlist[nent];
 110 #ifndef DONT_NEED_AIO_MISC_COND
 111   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 112 #endif
 113   int cnt;
 114   bool any = false;
 115   int result = 0;
 116   int cntr = 1;
 117
 118   /* Request the mutex.  */
 119   pthread_mutex_lock (&__aio_requests_mutex);
 120
 121   /* There is not yet a finished request.  Signal the request that
 122      we are working for it.  */
 123   for (cnt = 0; cnt < nent; ++cnt)
 124     if (list[cnt] != NULL)
 125       {
 126         if (list[cnt]->__error_code == EINPROGRESS)
 127           {
 128             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 129
 130             if (requestlist[cnt] != NULL)
 131               {
 132 #ifndef DONT_NEED_AIO_MISC_COND
 133                 waitlist[cnt].cond = &cond;
 134 #endif
 135                 waitlist[cnt].result = NULL;
 136                 waitlist[cnt].next = requestlist[cnt]->waiting;
 137                 waitlist[cnt].counterp = &cntr;
 138                 waitlist[cnt].sigevp = NULL;
 139 #ifdef BROKEN_THREAD_SIGNALS
 140                 waitlist[cnt].caller_pid = 0;   /* Not needed.  */
 141 #endif
 142                 requestlist[cnt]->waiting = &waitlist[cnt];
 143                 any = true;
 144               }
 145             else
 146               /* We will never suspend.  */
 147               break;
 148           }
 149         else
 150           /* We will never suspend.  */
 151           break;
 152       }
 153
 154
 155   /* Only if none of the entries is NULL or finished to be wait.  */
 156   if (cnt == nent && any)
 157     {
 158       struct clparam clparam =
 159         {
 160           .list = list,
 161           .waitlist = waitlist,
 162           .requestlist = requestlist,
 163 #ifndef DONT_NEED_AIO_MISC_COND
 164           .cond = &cond,
 165 #endif
 166           .nent = nent
 167         };
 168
 169       pthread_cleanup_push (cleanup, &clparam);
 170
 171 #ifdef DONT_NEED_AIO_MISC_COND
 172       AIO_MISC_WAIT (result, cntr, timeout, 1);
 173 #else
 174       if (timeout == NULL)
 175         result = pthread_cond_wait (&cond, &__aio_requests_mutex);
 176       else
 177         {
 178           /* We have to convert the relative timeout value into an
 179              absolute time value with pthread_cond_timedwait expects.  */
 180           struct timeval now;
 181           struct timespec abstime;
 182
 183           __gettimeofday (&now, NULL);
 184           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 185           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 186           if (abstime.tv_nsec >= 1000000000)
 187             {
 188               abstime.tv_nsec -= 1000000000;
 189               abstime.tv_sec += 1;
 190             }
 191
 192           result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 193                                            &abstime);
 194         }
 195 #endif
 196
 197       pthread_cleanup_pop (0);
 198     }
 199
 200   /* Now remove the entry in the waiting list for all requests
 201      which didn't terminate.  */
 202   while (cnt-- > 0)
 203     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 204       {
 205         struct waitlist **listp;
 206
 207         assert (requestlist[cnt] != NULL);
 208
 209         /* There is the chance that we cannot find our entry anymore. This
 210            could happen if the request terminated and restarted again.  */
 211         listp = &requestlist[cnt]->waiting;
 212         while (*listp != NULL && *listp != &waitlist[cnt])
 213           listp = &(*listp)->next;
 214
 215         if (*listp != NULL)
 216           *listp = (*listp)->next;
 217       }
 218
 219 #ifndef DONT_NEED_AIO_MISC_COND
 220   /* Release the conditional variable.  */
 221   if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
 222     /* This must never happen.  */
 223     abort ();
 224 #endif
 225
 226   if (result != 0)
 227     {
 228 #ifndef DONT_NEED_AIO_MISC_COND
 229       /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
 230          the timeout error report of `pthread_cond_timedwait' to the
 231          form expected from `aio_suspend'.  */
 232       if (result == ETIMEDOUT)
 233         __set_errno (EAGAIN);
 234       else
 235 #endif
 236         __set_errno (result);
 237
 238       result = -1;
 239     }
 240
 241   /* Release the mutex.  */
 242   pthread_mutex_unlock (&__aio_requests_mutex);
 243
 244   return result;
 245 }
 246
 247 weak_alias (aio_suspend, aio_suspend64)