nptl/sysdeps/unix/sysv/linux/sparc/sparc32/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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <sysdep.h>
  23 #include <lowlevellock.h>
  24 #include <internaltypes.h>
  25 #include <semaphore.h>
  26
  27 #include <pthreadP.h>
  28 #include <shlib-compat.h>
  29
  30
  31 void
  32 attribute_hidden
  33 __sem_wait_cleanup (void *arg)
  34 {
  35   struct sparc_new_sem *isem = (struct sparc_new_sem *) arg;
  36
  37   if (__atomic_is_v9)
  38     atomic_decrement (&isem->nwaiters);
  39   else
  40     {
  41       __sparc32_atomic_do_lock24 (&isem->lock);
  42       isem->nwaiters--;
  43       __sparc32_atomic_do_unlock24 (&isem->lock);
  44     }
  45 }
  46
  47
  48 int
  49 __new_sem_wait (sem_t *sem)
  50 {
  51   struct sparc_new_sem *isem = (struct sparc_new_sem *) sem;
  52   int err;
  53   int val;
  54
  55   if (__atomic_is_v9)
  56     val = atomic_decrement_if_positive (&isem->value);
  57   else
  58     {
  59       __sparc32_atomic_do_lock24 (&isem->lock);
  60       val = isem->value;
  61       if (val > 0)
  62         isem->value = val - 1;
  63       else
  64         isem->nwaiters++;
  65       __sparc32_atomic_do_unlock24 (&isem->lock);
  66     }
  67
  68   if (val > 0)
  69     return 0;
  70
  71   if (__atomic_is_v9)
  72     atomic_increment (&isem->nwaiters);
  73   else
  74     /* Already done above while still holding isem->lock.  */;
  75
  76   pthread_cleanup_push (__sem_wait_cleanup, isem);
  77
  78   while (1)
  79     {
  80       /* Enable asynchronous cancellation.  Required by the standard.  */
  81       int oldtype = __pthread_enable_asynccancel ();
  82
  83       err = lll_futex_wait (&isem->value, 0,
  84                             isem->private ^ FUTEX_PRIVATE_FLAG);
  85
  86       /* Disable asynchronous cancellation.  */
  87       __pthread_disable_asynccancel (oldtype);
  88
  89       if (err != 0 && err != -EWOULDBLOCK)
  90         {
  91           __set_errno (-err);
  92           err = -1;
  93           break;
  94         }
  95
  96       if (__atomic_is_v9)
  97         val = atomic_decrement_if_positive (&isem->value);
  98       else
  99         {
 100           __sparc32_atomic_do_lock24 (&isem->lock);
 101           val = isem->value;
 102           if (val > 0)
 103             isem->value = val - 1;
 104           __sparc32_atomic_do_unlock24 (&isem->lock);
 105         }
 106
 107       if (val > 0)
 108         {
 109           err = 0;
 110           break;
 111         }
 112     }
 113
 114   pthread_cleanup_pop (0);
 115
 116   if (__atomic_is_v9)
 117     atomic_decrement (&isem->nwaiters);
 118   else
 119     {
 120       __sparc32_atomic_do_lock24 (&isem->lock);
 121       isem->nwaiters--;
 122       __sparc32_atomic_do_unlock24 (&isem->lock);
 123     }
 124
 125   return err;
 126 }
 127 versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
 128
 129
 130 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
 131 int
 132 attribute_compat_text_section
 133 __old_sem_wait (sem_t *sem)
 134 {
 135   struct sparc_old_sem *isem = (struct sparc_old_sem *) sem;
 136   int err;
 137   int val;
 138
 139   do
 140     {
 141       if (__atomic_is_v9)
 142         val = atomic_decrement_if_positive (&isem->value);
 143       else
 144         {
 145           __sparc32_atomic_do_lock24 (&isem->lock);
 146           val = isem->value;
 147           if (val > 0)
 148             isem->value = val - 1;
 149           __sparc32_atomic_do_unlock24 (&isem->lock);
 150         }
 151
 152       if (val > 0)
 153         return 0;
 154
 155       /* Enable asynchronous cancellation.  Required by the standard.  */
 156       int oldtype = __pthread_enable_asynccancel ();
 157
 158       err = lll_futex_wait (futex, 0,
 159                             isem->private ^ FUTEX_PRIVATE_FLAG);
 160
 161       /* Disable asynchronous cancellation.  */
 162       __pthread_disable_asynccancel (oldtype);
 163     }
 164   while (err == 0 || err == -EWOULDBLOCK);
 165
 166   __set_errno (-err);
 167   return -1;
 168 }
 169
 170 compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
 171 #endif