nptl/sysdeps/unix/sysv/linux/sparc/sem_wait.c

   1 /* sem_wait -- wait on a semaphore.  Generic futex-using version.
   2    Copyright (C) 2003, 2007 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
   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 #include <errno.h>
  21 #include <sysdep.h>
  22 #include <lowlevellock.h>
  23 #include <internaltypes.h>
  24 #include <semaphore.h>
  25
  26 #include <pthreadP.h>
  27 #include <shlib-compat.h>
  28
  29
  30 void
  31 attribute_hidden
  32 __sem_wait_cleanup (void *arg)
  33 {
  34   struct sparc_new_sem *isem = (struct sparc_new_sem *) arg;
  35
  36   atomic_decrement (&isem->nwaiters);
  37 }
  38
  39 /* This is in a seperate function in order to make sure gcc
  40    puts the call site into an exception region, and thus the
  41    cleanups get properly run.  */
  42 static int
  43 __attribute__ ((noinline))
  44 do_futex_wait (struct sparc_new_sem *isem)
  45 {
  46   int err, oldtype = __pthread_enable_asynccancel ();
  47
  48   err = lll_futex_wait (&isem->value, 0, isem->private ^ FUTEX_PRIVATE_FLAG);
  49
  50   __pthread_disable_asynccancel (oldtype);
  51   return err;
  52 }
  53
  54 int
  55 __new_sem_wait (sem_t *sem)
  56 {
  57   struct sparc_new_sem *isem = (struct sparc_new_sem *) sem;
  58   int err;
  59
  60   if (atomic_decrement_if_positive (&isem->value) > 0)
  61     return 0;
  62
  63   atomic_increment (&isem->nwaiters);
  64
  65   pthread_cleanup_push (__sem_wait_cleanup, isem);
  66
  67   while (1)
  68     {
  69       err = do_futex_wait(isem);
  70       if (err != 0 && err != -EWOULDBLOCK)
  71         {
  72           __set_errno (-err);
  73           err = -1;
  74           break;
  75         }
  76
  77       if (atomic_decrement_if_positive (&isem->value) > 0)
  78         {
  79           err = 0;
  80           break;
  81         }
  82     }
  83
  84   pthread_cleanup_pop (0);
  85
  86   atomic_decrement (&isem->nwaiters);
  87
  88   return err;
  89 }
  90 versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
  91
  92
  93 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
  94 int
  95 attribute_compat_text_section
  96 __old_sem_wait (sem_t *sem)
  97 {
  98   struct sparc_old_sem *isem = (struct sparc_old_sem *) sem;
  99   int err;
 100
 101   do
 102     {
 103       if (atomic_decrement_if_positive (&isem->value) > 0)
 104         return 0;
 105
 106       /* Enable asynchronous cancellation.  Required by the standard.  */
 107       int oldtype = __pthread_enable_asynccancel ();
 108
 109       err = lll_futex_wait (&isem->value, 0,
 110                             isem->private ^ FUTEX_PRIVATE_FLAG);
 111
 112       /* Disable asynchronous cancellation.  */
 113       __pthread_disable_asynccancel (oldtype);
 114     }
 115   while (err == 0 || err == -EWOULDBLOCK);
 116
 117   __set_errno (-err);
 118   return -1;
 119 }
 120
 121 compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
 122 #endif