nptl/sysdeps/pthread/aio_misc.h

   1 /* Copyright (C) 2006 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 /* We define a special synchronization primitive for AIO.  POSIX
  20    conditional variables would be ideal but the pthread_cond_*wait
  21    operations do not return on EINTR.  This is a requirement for
  22    correct aio_suspend and lio_listio implementations.  */
  23
  24 #include <assert.h>
  25 #include <pthreadP.h>
  26 #include <lowlevellock.h>
  27
  28 #define DONT_NEED_AIO_MISC_COND 1
  29
  30 #define AIO_MISC_NOTIFY(waitlist) \
  31   do {                                                                        \
  32     if (--*waitlist->counterp == 0)                                           \
  33       lll_futex_wake (waitlist->counterp, 1);                                 \
  34   } while (0)
  35
  36 #define AIO_MISC_WAIT(result, futex, timeout, cancel)                         \
  37   do {                                                                        \
  38     volatile int *futexaddr = &futex;                                         \
  39     int oldval = futex;                                                       \
  40                                                                               \
  41     if (oldval != 0)                                                          \
  42       {                                                                       \
  43         pthread_mutex_unlock (&__aio_requests_mutex);                         \
  44                                                                               \
  45         int oldtype;                                                          \
  46         if (cancel)                                                           \
  47           oldtype = LIBC_CANCEL_ASYNC ();                                     \
  48                                                                               \
  49         int status;                                                           \
  50         do                                                                    \
  51           {                                                                   \
  52             status = lll_futex_timed_wait (futexaddr, oldval, timeout);       \
  53             if (status != -EWOULDBLOCK)                                       \
  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 == -EWOULDBLOCK);                     \
  69                                                                               \
  70         pthread_mutex_lock (&__aio_requests_mutex);                           \
  71       }                                                                       \
  72   } while (0)
  73
  74 #include_next <aio_misc.h>