sysdeps/pthread/aio_suspend.c

   1 /* Suspend until termination of a requests.
   2    Copyright (C) 1997-2018 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 <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 (unsigned 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 (const struct aiocb *const list[], int nent,
 109              const struct timespec *timeout)
 110 {
 111   if (__glibc_unlikely (nent < 0))
 112     {
 113       __set_errno (EINVAL);
 114       return -1;
 115     }
 116
 117   struct waitlist waitlist[nent];
 118   struct requestlist *requestlist[nent];
 119 #ifndef DONT_NEED_AIO_MISC_COND
 120   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 121 #endif
 122   int cnt;
 123   bool any = false;
 124   int result = 0;
 125   unsigned int cntr = 1;
 126
 127   /* Request the mutex.  */
 128   pthread_mutex_lock (&__aio_requests_mutex);
 129
 130   /* There is not yet a finished request.  Signal the request that
 131      we are working for it.  */
 132   for (cnt = 0; cnt < nent; ++cnt)
 133     if (list[cnt] != NULL)
 134       {
 135         if (list[cnt]->__error_code == EINPROGRESS)
 136           {
 137             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 138
 139             if (requestlist[cnt] != NULL)
 140               {
 141 #ifndef DONT_NEED_AIO_MISC_COND
 142                 waitlist[cnt].cond = &cond;
 143 #endif
 144                 waitlist[cnt].result = NULL;
 145                 waitlist[cnt].next = requestlist[cnt]->waiting;
 146                 waitlist[cnt].counterp = &cntr;
 147                 waitlist[cnt].sigevp = NULL;
 148                 requestlist[cnt]->waiting = &waitlist[cnt];
 149                 any = true;
 150               }
 151             else
 152               /* We will never suspend.  */
 153               break;
 154           }
 155         else
 156           /* We will never suspend.  */
 157           break;
 158       }
 159
 160
 161   /* Only if none of the entries is NULL or finished to be wait.  */
 162   if (cnt == nent && any)
 163     {
 164       struct clparam clparam =
 165         {
 166           .list = list,
 167           .waitlist = waitlist,
 168           .requestlist = requestlist,
 169 #ifndef DONT_NEED_AIO_MISC_COND
 170           .cond = &cond,
 171 #endif
 172           .nent = nent
 173         };
 174
 175       pthread_cleanup_push (cleanup, &clparam);
 176
 177 #ifdef DONT_NEED_AIO_MISC_COND
 178       result = do_aio_misc_wait (&cntr, timeout);
 179 #else
 180       if (timeout == NULL)
 181         result = pthread_cond_wait (&cond, &__aio_requests_mutex);
 182       else
 183         {
 184           /* We have to convert the relative timeout value into an
 185              absolute time value with pthread_cond_timedwait expects.  */
 186           struct timeval now;
 187           struct timespec abstime;
 188
 189           __gettimeofday (&now, NULL);
 190           abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
 191           abstime.tv_sec = timeout->tv_sec + now.tv_sec;
 192           if (abstime.tv_nsec >= 1000000000)
 193             {
 194               abstime.tv_nsec -= 1000000000;
 195               abstime.tv_sec += 1;
 196             }
 197
 198           result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 199                                            &abstime);
 200         }
 201 #endif
 202
 203       pthread_cleanup_pop (0);
 204     }
 205
 206   /* Now remove the entry in the waiting list for all requests
 207      which didn't terminate.  */
 208   while (cnt-- > 0)
 209     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 210       {
 211         struct waitlist **listp;
 212
 213         assert (requestlist[cnt] != NULL);
 214
 215         /* There is the chance that we cannot find our entry anymore. This
 216            could happen if the request terminated and restarted again.  */
 217         listp = &requestlist[cnt]->waiting;
 218         while (*listp != NULL && *listp != &waitlist[cnt])
 219           listp = &(*listp)->next;
 220
 221         if (*listp != NULL)
 222           *listp = (*listp)->next;
 223       }
 224
 225 #ifndef DONT_NEED_AIO_MISC_COND
 226   /* Release the conditional variable.  */
 227   if (__glibc_unlikely (pthread_cond_destroy (&cond) != 0))
 228     /* This must never happen.  */
 229     abort ();
 230 #endif
 231
 232   if (result != 0)
 233     {
 234 #ifndef DONT_NEED_AIO_MISC_COND
 235       /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
 236          the timeout error report of `pthread_cond_timedwait' to the
 237          form expected from `aio_suspend'.  */
 238       if (result == ETIMEDOUT)
 239         __set_errno (EAGAIN);
 240       else
 241 #endif
 242         __set_errno (result);
 243
 244       result = -1;
 245     }
 246
 247   /* Release the mutex.  */
 248   pthread_mutex_unlock (&__aio_requests_mutex);
 249
 250   return result;
 251 }
 252
 253 weak_alias (aio_suspend, aio_suspend64)