sysdeps/sparc/sparc32/sem_wait.c

   1 /* sem_wait -- wait on a semaphore.  Generic futex-using version.
   2    Copyright (C) 2003-2015 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 #include <sparc-nptl.h>
  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   if (__atomic_is_v9)
  37     atomic_decrement (&isem->nwaiters);
  38   else
  39     {
  40       __sparc32_atomic_do_lock24 (&isem->lock);
  41       isem->nwaiters--;
  42       __sparc32_atomic_do_unlock24 (&isem->lock);
  43     }
  44 }
  45
  46 /* This is in a seperate function in order to make sure gcc
  47    puts the call site into an exception region, and thus the
  48    cleanups get properly run.  */
  49 static int
  50 __attribute__ ((noinline))
  51 do_futex_wait (struct sparc_new_sem *isem)
  52 {
  53   int err, oldtype = __pthread_enable_asynccancel ();
  54
  55   err = lll_futex_wait (&isem->value, 0, isem->private ^ FUTEX_PRIVATE_FLAG);
  56
  57   __pthread_disable_asynccancel (oldtype);
  58   return err;
  59 }
  60
  61 int
  62 __new_sem_wait (sem_t *sem)
  63 {
  64   struct sparc_new_sem *isem = (struct sparc_new_sem *) sem;
  65   int err;
  66   int val;
  67
  68   if (__atomic_is_v9)
  69     val = atomic_decrement_if_positive (&isem->value);
  70   else
  71     {
  72       __sparc32_atomic_do_lock24 (&isem->lock);
  73       val = isem->value;
  74       if (val > 0)
  75         isem->value = val - 1;
  76       else
  77         isem->nwaiters++;
  78       __sparc32_atomic_do_unlock24 (&isem->lock);
  79     }
  80
  81   if (val > 0)
  82     return 0;
  83
  84   if (__atomic_is_v9)
  85     atomic_increment (&isem->nwaiters);
  86   else
  87     /* Already done above while still holding isem->lock.  */;
  88
  89   pthread_cleanup_push (__sem_wait_cleanup, isem);
  90
  91   while (1)
  92     {
  93       err = do_futex_wait(isem);
  94       if (err != 0 && err != -EWOULDBLOCK)
  95         {
  96           __set_errno (-err);
  97           err = -1;
  98           break;
  99         }
 100
 101       if (__atomic_is_v9)
 102         val = atomic_decrement_if_positive (&isem->value);
 103       else
 104         {
 105           __sparc32_atomic_do_lock24 (&isem->lock);
 106           val = isem->value;
 107           if (val > 0)
 108             isem->value = val - 1;
 109           __sparc32_atomic_do_unlock24 (&isem->lock);
 110         }
 111
 112       if (val > 0)
 113         {
 114           err = 0;
 115           break;
 116         }
 117     }
 118
 119   pthread_cleanup_pop (0);
 120
 121   if (__atomic_is_v9)
 122     atomic_decrement (&isem->nwaiters);
 123   else
 124     {
 125       __sparc32_atomic_do_lock24 (&isem->lock);
 126       isem->nwaiters--;
 127       __sparc32_atomic_do_unlock24 (&isem->lock);
 128     }
 129
 130   return err;
 131 }
 132 versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
 133
 134
 135 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
 136 int
 137 attribute_compat_text_section
 138 __old_sem_wait (sem_t *sem)
 139 {
 140   struct sparc_old_sem *isem = (struct sparc_old_sem *) sem;
 141   int err;
 142   int val;
 143
 144   do
 145     {
 146       if (__atomic_is_v9)
 147         val = atomic_decrement_if_positive (&isem->value);
 148       else
 149         {
 150           __sparc32_atomic_do_lock24 (&isem->lock);
 151           val = isem->value;
 152           if (val > 0)
 153             isem->value = val - 1;
 154           __sparc32_atomic_do_unlock24 (&isem->lock);
 155         }
 156
 157       if (val > 0)
 158         return 0;
 159
 160       /* Enable asynchronous cancellation.  Required by the standard.  */
 161       int oldtype = __pthread_enable_asynccancel ();
 162
 163       err = lll_futex_wait (&isem->value, 0,
 164                             isem->private ^ FUTEX_PRIVATE_FLAG);
 165
 166       /* Disable asynchronous cancellation.  */
 167       __pthread_disable_asynccancel (oldtype);
 168     }
 169   while (err == 0 || err == -EWOULDBLOCK);
 170
 171   __set_errno (-err);
 172   return -1;
 173 }
 174
 175 compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
 176 #endif