nptl/sysdeps/unix/sysv/linux/powerpc/sem_post.c

   1 /* sem_post -- post to a POSIX semaphore.  Powerpc version.
   2    Copyright (C) 2003, 2004, 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 <shlib-compat.h>
  28
  29 int
  30 __new_sem_post (sem_t *sem)
  31 {
  32   struct new_sem *isem = (struct new_sem *) sem;
  33
  34   __asm __volatile (__lll_rel_instr ::: "memory");
  35   atomic_increment (&isem->value);
  36   __asm __volatile (__lll_acq_instr ::: "memory");
  37   if (isem->nwaiters > 0)
  38     {
  39       int err = lll_futex_wake (&isem->value, 1,
  40                                 isem->private ^ FUTEX_PRIVATE_FLAG);
  41       if (__builtin_expect (err, 0) < 0)
  42         {
  43           __set_errno (-err);
  44           return -1;
  45         }
  46     }
  47   return 0;
  48 }
  49 versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1);
  50
  51 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
  52
  53 int
  54 attribute_compat_text_section
  55 __old_sem_post (sem_t *sem)
  56 {
  57   int *futex = (int *) sem;
  58
  59   __asm __volatile (__lll_rel_instr ::: "memory");
  60   int nr = atomic_increment_val (futex);
  61   /* We always have to assume it is a shared semaphore.  */
  62   int err = lll_futex_wake (futex, 1, LLL_SHARED);
  63   if (__builtin_expect (err, 0) < 0)
  64     {
  65       __set_errno (-err);
  66       return -1;
  67     }
  68   return 0;
  69 }
  70
  71 compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0);
  72 #endif