sysdeps/nptl/aio_misc.h

   1 /* Copyright (C) 2006-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 /* We define a special synchronization primitive for AIO.  POSIX
  19    conditional variables would be ideal but the pthread_cond_*wait
  20    operations do not return on EINTR.  This is a requirement for
  21    correct aio_suspend and lio_listio implementations.  */
  22
  23 #include <assert.h>
  24 #include <nptl/pthreadP.h>
  25 #include <futex-internal.h>
  26
  27 #define DONT_NEED_AIO_MISC_COND 1
  28
  29 #define AIO_MISC_NOTIFY(waitlist) \
  30   do {                                                                        \
  31     if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)                \
  32       futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE);     \
  33   } while (0)
  34
  35 #define AIO_MISC_WAIT(result, futex, timeout, cancel)                         \
  36   do {                                                                        \
  37     volatile unsigned int *futexaddr = &futex;                                \
  38     unsigned int oldval = futex;                                              \
  39                                                                               \
  40     if (oldval != 0)                                                          \
  41       {                                                                       \
  42         pthread_mutex_unlock (&__aio_requests_mutex);                         \
  43                                                                               \
  44         int oldtype;                                                          \
  45         if (cancel)                                                           \
  46           oldtype = LIBC_CANCEL_ASYNC ();                                     \
  47                                                                               \
  48         int status;                                                           \
  49         do                                                                    \
  50           {                                                                   \
  51             status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
  52                                           timeout, FUTEX_PRIVATE);            \
  53             if (status != EAGAIN)                                             \
  54               break;                                                          \
  55                                                                               \
  56             oldval = *futexaddr;                                              \
  57           }                                                                   \
  58         while (oldval != 0);                                                  \
  59                                                                               \
  60         if (cancel)                                                           \
  61           LIBC_CANCEL_RESET (oldtype);                                        \
  62                                                                               \
  63         if (status == EINTR)                                                  \
  64           result = EINTR;                                                     \
  65         else if (status == ETIMEDOUT)                                         \
  66           result = EAGAIN;                                                    \
  67         else                                                                  \
  68           assert (status == 0 || status == EAGAIN);                           \
  69                                                                               \
  70         pthread_mutex_lock (&__aio_requests_mutex);                           \
  71       }                                                                       \
  72   } while (0)
  73
  74 #include_next <aio_misc.h>