sysdeps/pthread/aio_suspend.c

   1 /* Suspend until termination of a requests.
   2    Copyright (C) 1997-2014 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20
  21 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  22    implementations of aio_suspend and aio_suspend64 are identical and so
  23    we want to avoid code duplication by using aliases.  But gcc sees
  24    the different parameter lists and prints a warning.  We define here
  25    a function so that aio_suspend64 has no prototype.  */
  26 #define aio_suspend64 XXX
  27 #include <aio.h>
  28 /* And undo the hack.  */
  29 #undef aio_suspend64
  30
  31 #include <assert.h>
  32 #include <errno.h>
  33 #include <stdbool.h>
  34 #include <stdlib.h>
  35 #include <sys/time.h>
  36
  37 #include <bits/libc-lock.h>
  38 #include <aio_misc.h>
  39
  40
  41 struct clparam
  42 {
  43   const struct aiocb *const *list;
  44   struct waitlist *waitlist;
  45   struct requestlist **requestlist;
  46 #ifndef DONT_NEED_AIO_MISC_COND
  47   pthread_cond_t *cond;
  48 #endif
  49   int nent;
  50 };
  51
  52
  53 static void
  54 cleanup (void *arg)
  55 {
  56 #ifdef DONT_NEED_AIO_MISC_COND
  57   /* Acquire the mutex.  If pthread_cond_*wait is used this would
  58      happen implicitly.  */
  59   pthread_mutex_lock (&__aio_requests_mutex);
  60 #endif
  61
  62   const struct clparam *param = (const struct clparam *) arg;
  63
  64   /* Now remove the entry in the waiting list for all requests
  65      which didn't terminate.  */
  66   int cnt = param->nent;
  67   while (cnt-- > 0)
  68     if (param->list[cnt] != NULL
  69         && param->list[cnt]->__error_code == EINPROGRESS)
  70       {
  71         struct waitlist **listp;
  72
  73         assert (param->requestlist[cnt] != NULL);
  74
  75         /* There is the chance that we cannot find our entry anymore. This
  76            could happen if the request terminated and restarted again.  */
  77         listp = &param->requestlist[cnt]->waiting;
  78         while (*listp != NULL && *listp != &param->waitlist[cnt])
  79           listp = &(*listp)->next;
  80
  81         if (*listp != NULL)
  82           *listp = (*listp)->next;
  83       }
  84
  85 #ifndef DONT_NEED_AIO_MISC_COND
  86   /* Release the conditional variable.  */
  87   (void) pthread_cond_destroy (param->cond);
  88 #endif
  89
  90   /* Release the mutex.  */
  91   pthread_mutex_unlock (&__aio_requests_mutex);
  92 }
  93
  94 #ifdef DONT_NEED_AIO_MISC_COND
  95 static int
  96 __attribute__ ((noinline))
  97 do_aio_misc_wait(int *cntr, const struct timespec *timeout)
  98 {
  99         int result = 0;
 100
 101         AIO_MISC_WAIT(result, *cntr, timeout, 1);
 102
 103         return result;
 104 }
 105 #endif
 106
 107 int
 108 aio_suspend (list, nent, timeout)
 109      const struct aiocb *const list[];
 110      int nent;
 111      const struct timespec *timeout;
 112 {
 113   if (__builtin_expect (nent < 0, 0))
 114     {
 115       __set_errno (EINVAL);
 116       return -1;
 117     }
 118
 119   struct waitlist waitlist[nent];
 120   struct requestlist *requestlist[nent];
 121 #ifndef DONT_NEED_AIO_MISC_COND
 122   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 123 #endif
 124   int cnt;
 125   bool any = false;
 126   int result = 0;
 127   int cntr = 1;
 128
 129   /* Request the mutex.  */
 130   pthread_mutex_lock (&__aio_requests_mutex);
 131
 132   /* There is not yet a finished request.  Signal the request that
 133      we are working for it.  */
 134   for (cnt = 0; cnt < nent; ++cnt)
 135     if (list[cnt] != NULL)
 136       {
 137         if (list[cnt]->__error_code == EINPROGRESS)
 138           {
 139             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 140
 141             if (requestlist[cnt] != NULL)
 142               {
 143 #ifndef DONT_NEED_AIO_MISC_COND
 144                 waitlist[cnt].cond = &cond;
 145 #endif
 146                 waitlist[cnt].result = NULL;
 147                 waitlist[cnt].next = requestlist[cnt]->waiting;
 148                 waitlist[cnt].counterp = &cntr;
 149                 waitlist[cnt].sigevp = NULL;
 150 #ifdef BROKEN_THREAD_SIGNALS
 151                 waitlist[cnt].caller_pid = 0;   /* Not needed.  */
 152 #endif
 153                 requestlist[cnt]->waiting = &waitlist[cnt];
 154                 any = true;
 155               }
 156             else
 157               /* We will never suspend.  */
 158               break;
 159           }
 160         else
 161           /* We will never suspend.  */
 162           break;
 163       }
 164
 165
 166   /* Only if none of the entries is NULL or finished to be wait.  */
 167   if (cnt == nent && any)
 168     {
 169       struct clparam clparam =
 170         {
 171           .list = list,
 172           .waitlist = waitlist,
 173           .requestlist = requestlist,
 174 #ifndef DONT_NEED_AIO_MISC_COND
 175           .cond = &cond,
 176 #endif
 177           .nent = nent
 178         };
 179
 180       pthread_cleanup_push (cleanup, &clparam);
 181
 182 #ifdef DONT_NEED_AIO_MISC_COND
 183       result = do_aio_misc_wait(&cntr, timeout);
 184 #else
 185       if (timeout == NULL)
 186         result = pthread_cond_wait (&cond, &__aio_requests_mutex);
 187       else
 188         {
 189           /* We have to convert the relative timeout value into an
 190              absolute time value with pthread_cond_timedwait expects.  */
 191           struct timeval now;
 192           struct timespec abstime;
 193
 194           __gettimeofday (&now, NULL);
 195           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 196           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 197           if (abstime.tv_nsec >= 1000000000)
 198             {
 199               abstime.tv_nsec -= 1000000000;
 200               abstime.tv_sec += 1;
 201             }
 202
 203           result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 204                                            &abstime);
 205         }
 206 #endif
 207
 208       pthread_cleanup_pop (0);
 209     }
 210
 211   /* Now remove the entry in the waiting list for all requests
 212      which didn't terminate.  */
 213   while (cnt-- > 0)
 214     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 215       {
 216         struct waitlist **listp;
 217
 218         assert (requestlist[cnt] != NULL);
 219
 220         /* There is the chance that we cannot find our entry anymore. This
 221            could happen if the request terminated and restarted again.  */
 222         listp = &requestlist[cnt]->waiting;
 223         while (*listp != NULL && *listp != &waitlist[cnt])
 224           listp = &(*listp)->next;
 225
 226         if (*listp != NULL)
 227           *listp = (*listp)->next;
 228       }
 229
 230 #ifndef DONT_NEED_AIO_MISC_COND
 231   /* Release the conditional variable.  */
 232   if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
 233     /* This must never happen.  */
 234     abort ();
 235 #endif
 236
 237   if (result != 0)
 238     {
 239 #ifndef DONT_NEED_AIO_MISC_COND
 240       /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
 241          the timeout error report of `pthread_cond_timedwait' to the
 242          form expected from `aio_suspend'.  */
 243       if (result == ETIMEDOUT)
 244         __set_errno (EAGAIN);
 245       else
 246 #endif
 247         __set_errno (result);
 248
 249       result = -1;
 250     }
 251
 252   /* Release the mutex.  */
 253   pthread_mutex_unlock (&__aio_requests_mutex);
 254
 255   return result;
 256 }
 257
 258 weak_alias (aio_suspend, aio_suspend64)