rt/aio_suspend.c

   1 /* Suspend until termination of a requests.
   2    Copyright (C) 1997-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19
  20 /* We use an UGLY hack to prevent gcc from finding us cheating.  The
  21    implementations of aio_suspend and aio_suspend64 are identical and so
  22    we want to avoid code duplication by using aliases.  But gcc sees
  23    the different parameter lists and prints a warning.  We define here
  24    a function so that aio_suspend64 has no prototype.  */
  25 #define aio_suspend64 XXX
  26 #include <aio.h>
  27 /* And undo the hack.  */
  28 #undef aio_suspend64
  29
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <stdbool.h>
  33 #include <stdlib.h>
  34 #include <sys/time.h>
  35
  36 #include <libc-lock.h>
  37 #include <aio_misc.h>
  38 #include <pthreadP.h>
  39 #include <shlib-compat.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 (unsigned int *cntr, const struct __timespec64 *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_time64 (const struct aiocb *const list[], int nent,
 110                       const struct __timespec64 *timeout)
 111 {
 112   if (__glibc_unlikely (nent < 0))
 113     {
 114       __set_errno (EINVAL);
 115       return -1;
 116     }
 117
 118   struct waitlist waitlist[nent];
 119   struct requestlist *requestlist[nent];
 120 #ifndef DONT_NEED_AIO_MISC_COND
 121   pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
 122 #endif
 123   int cnt;
 124   bool any = false;
 125   int result = 0;
 126   unsigned int cntr = 1;
 127
 128   /* Request the mutex.  */
 129   __pthread_mutex_lock (&__aio_requests_mutex);
 130
 131   /* There is not yet a finished request.  Signal the request that
 132      we are working for it.  */
 133   for (cnt = 0; cnt < nent; ++cnt)
 134     if (list[cnt] != NULL)
 135       {
 136         if (list[cnt]->__error_code == EINPROGRESS)
 137           {
 138             requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
 139
 140             if (requestlist[cnt] != NULL)
 141               {
 142 #ifndef DONT_NEED_AIO_MISC_COND
 143                 waitlist[cnt].cond = &cond;
 144 #endif
 145                 waitlist[cnt].result = NULL;
 146                 waitlist[cnt].next = requestlist[cnt]->waiting;
 147                 waitlist[cnt].counterp = &cntr;
 148                 waitlist[cnt].sigevp = NULL;
 149                 requestlist[cnt]->waiting = &waitlist[cnt];
 150                 any = true;
 151               }
 152             else
 153               /* We will never suspend.  */
 154               break;
 155           }
 156         else
 157           /* We will never suspend.  */
 158           break;
 159       }
 160
 161   struct __timespec64 ts;
 162   if (timeout != NULL)
 163     {
 164       __clock_gettime64 (CLOCK_MONOTONIC, &ts);
 165       ts.tv_sec += timeout->tv_sec;
 166       ts.tv_nsec += timeout->tv_nsec;
 167       if (ts.tv_nsec >= 1000000000)
 168         {
 169           ts.tv_nsec -= 1000000000;
 170           ts.tv_sec++;
 171         }
 172     }
 173
 174   /* Only if none of the entries is NULL or finished to be wait.  */
 175   if (cnt == nent && any)
 176     {
 177       struct clparam clparam =
 178         {
 179           .list = list,
 180           .waitlist = waitlist,
 181           .requestlist = requestlist,
 182 #ifndef DONT_NEED_AIO_MISC_COND
 183           .cond = &cond,
 184 #endif
 185           .nent = nent
 186         };
 187
 188 #if PTHREAD_IN_LIBC
 189       __libc_cleanup_region_start (1, cleanup, &clparam);
 190 #else
 191       __pthread_cleanup_push (cleanup, &clparam);
 192 #endif
 193
 194 #ifdef DONT_NEED_AIO_MISC_COND
 195       result = do_aio_misc_wait (&cntr, timeout == NULL ? NULL : &ts);
 196 #else
 197       struct timespec ts32 = valid_timespec64_to_timespec (ts);
 198       result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
 199                                        timeout == NULL ? NULL : &ts32);
 200 #endif
 201
 202 #if PTHREAD_IN_LIBC
 203       __libc_cleanup_region_end (0);
 204 #else
 205       pthread_cleanup_pop (0);
 206 #endif
 207     }
 208
 209   /* Now remove the entry in the waiting list for all requests
 210      which didn't terminate.  */
 211   while (cnt-- > 0)
 212     if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
 213       {
 214         struct waitlist **listp;
 215
 216         assert (requestlist[cnt] != NULL);
 217
 218         /* There is the chance that we cannot find our entry anymore. This
 219            could happen if the request terminated and restarted again.  */
 220         listp = &requestlist[cnt]->waiting;
 221         while (*listp != NULL && *listp != &waitlist[cnt])
 222           listp = &(*listp)->next;
 223
 224         if (*listp != NULL)
 225           *listp = (*listp)->next;
 226       }
 227
 228 #ifndef DONT_NEED_AIO_MISC_COND
 229   /* Release the conditional variable.  */
 230   if (__glibc_unlikely (pthread_cond_destroy (&cond) != 0))
 231     /* This must never happen.  */
 232     abort ();
 233 #endif
 234
 235   if (result != 0)
 236     {
 237 #ifndef DONT_NEED_AIO_MISC_COND
 238       /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
 239          the timeout error report of `pthread_cond_timedwait' to the
 240          form expected from `aio_suspend'.  */
 241       if (result == ETIMEDOUT)
 242         __set_errno (EAGAIN);
 243       else
 244 #endif
 245         __set_errno (result);
 246
 247       result = -1;
 248     }
 249
 250   /* Release the mutex.  */
 251   __pthread_mutex_unlock (&__aio_requests_mutex);
 252
 253   return result;
 254 }
 255
 256 #if __TIMESIZE == 64
 257 strong_alias (___aio_suspend_time64, __aio_suspend)
 258 #else /* __TIMESIZE != 64 */
 259 # if PTHREAD_IN_LIBC
 260 libc_hidden_ver (___aio_suspend_time64, __aio_suspend_time64)
 261 /* The conditional is slightly wrong: PTHREAD_IN_LIBC is a stand-in
 262    for whether time64 support is needed.  */
 263 versioned_symbol (libc, ___aio_suspend_time64, __aio_suspend_time64, GLIBC_2_34);
 264 # else
 265 librt_hidden_ver (___aio_suspend_time64, __aio_suspend_time64)
 266 # endif
 267
 268 int
 269 __aio_suspend (const struct aiocb *const list[], int nent,
 270                const struct timespec *timeout)
 271 {
 272   struct __timespec64 ts64;
 273
 274   if (timeout != NULL)
 275     ts64 = valid_timespec_to_timespec64 (*timeout);
 276
 277   return __aio_suspend_time64 (list, nent, timeout != NULL ? &ts64 : NULL);
 278 }
 279 #endif /* __TIMESPEC64 != 64 */
 280
 281 #if PTHREAD_IN_LIBC
 282 versioned_symbol (libc, __aio_suspend, aio_suspend, GLIBC_2_34);
 283 versioned_symbol (libc, __aio_suspend, aio_suspend64, GLIBC_2_34);
 284 # if OTHER_SHLIB_COMPAT (librt, GLIBC_2_1, GLIBC_2_34)
 285 compat_symbol (librt, __aio_suspend, aio_suspend, GLIBC_2_1);
 286 compat_symbol (librt, __aio_suspend, aio_suspend64, GLIBC_2_1);
 287 # endif
 288 #else /* !PTHREAD_IN_LIBC */
 289 weak_alias (__aio_suspend, aio_suspend)
 290 weak_alias (__aio_suspend, aio_suspend64)
 291 #endif /* !PTHREAD_IN_LIBC */