sysdeps/unix/bsd/bsd4.4/kfreebsd/fbtl/gai_misc.h

   1 /* Copyright (C) 2006-2013 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 <signal.h>
  25 #include <pthreadP.h>
  26 #include <lowlevellock.h>
  27
  28 #define DONT_NEED_GAI_MISC_COND 1
  29
  30 #define GAI_MISC_NOTIFY(waitlist) \
  31   do {                                                                        \
  32     if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)                \
  33       lll_futex_wake ((unsigned int *) waitlist->counterp, 1, LLL_PRIVATE);   \
  34   } while (0)
  35
  36 #warning have to check sign of return values from futex wait calls
  37
  38 #define GAI_MISC_WAIT(result, futex, timeout, cancel) \
  39   do {                                                                        \
  40     volatile int *futexaddr = &futex;                                         \
  41     int oldval = futex;                                                       \
  42                                                                               \
  43     if (oldval != 0)                                                          \
  44       {                                                                       \
  45         pthread_mutex_unlock (&__gai_requests_mutex);                         \
  46                                                                               \
  47         int oldtype;                                                          \
  48         if (cancel)                                                           \
  49           oldtype = LIBC_CANCEL_ASYNC ();                                     \
  50                                                                               \
  51         int status;                                                           \
  52         do                                                                    \
  53           {                                                                   \
  54             status = lll_futex_timed_wait ((unsigned int *) futexaddr, oldval,\
  55                                            timeout, LLL_PRIVATE);             \
  56             if (status != EWOULDBLOCK)                                        \
  57               break;                                                          \
  58                                                                               \
  59             oldval = *futexaddr;                                              \
  60           }                                                                   \
  61         while (oldval != 0);                                                  \
  62                                                                               \
  63         if (cancel)                                                           \
  64           LIBC_CANCEL_RESET (oldtype);                                        \
  65                                                                               \
  66         if (status == EINTR)                                                  \
  67           result = EINTR;                                                     \
  68         else if (status == ETIMEDOUT)                                         \
  69           result = EAGAIN;                                                    \
  70         else                                                                  \
  71           assert (status == 0 || status == EWOULDBLOCK);                      \
  72                                                                               \
  73         pthread_mutex_lock (&__gai_requests_mutex);                           \
  74       }                                                                       \
  75   } while (0)
  76
  77
  78 #define gai_start_notify_thread __gai_start_notify_thread
  79 #define gai_create_helper_thread __gai_create_helper_thread
  80
  81 extern inline void
  82 __gai_start_notify_thread (void)
  83 {
  84   sigset_t ss;
  85   sigemptyset (&ss);
  86   INLINE_SYSCALL (sigprocmask, 3, SIG_SETMASK, &ss, NULL);
  87 }
  88
  89 extern inline int
  90 __gai_create_helper_thread (pthread_t *threadp, void *(*tf) (void *),
  91                             void *arg)
  92 {
  93   pthread_attr_t attr;
  94
  95   /* Make sure the thread is created detached.  */
  96   pthread_attr_init (&attr);
  97   pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
  98
  99   /* The helper thread needs only very little resources.  */
 100   (void) pthread_attr_setstacksize (&attr,
 101                                     __pthread_get_minstack (&attr)
 102                                     + 4 * PTHREAD_STACK_MIN);
 103
 104   /* Block all signals in the helper thread.  To do this thoroughly we
 105      temporarily have to block all signals here.  */
 106   sigset_t ss;
 107   sigset_t oss;
 108   sigfillset (&ss);
 109   INLINE_SYSCALL (sigprocmask, 3, SIG_SETMASK, &ss, &oss);
 110
 111   int ret = pthread_create (threadp, &attr, tf, arg);
 112
 113   /* Restore the signal mask.  */
 114   INLINE_SYSCALL (sigprocmask, 3, SIG_SETMASK, &oss, NULL);
 115
 116   (void) pthread_attr_destroy (&attr);
 117   return ret;
 118 }
 119
 120 #include <resolv/gai_misc.h>