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

   1 /* sem_post -- post to a POSIX semaphore.  Powerpc version.
   2    Copyright (C) 2003-2014 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 <shlib-compat.h>
  27
  28 int
  29 __new_sem_post (sem_t *sem)
  30 {
  31   struct new_sem *isem = (struct new_sem *) sem;
  32
  33   __asm __volatile (__lll_rel_instr ::: "memory");
  34   atomic_increment (&isem->value);
  35   __asm __volatile (__lll_acq_instr ::: "memory");
  36   if (isem->nwaiters > 0)
  37     {
  38       int err = lll_futex_wake (&isem->value, 1,
  39                                 isem->private ^ FUTEX_PRIVATE_FLAG);
  40       if (__builtin_expect (err, 0) < 0)
  41         {
  42           __set_errno (-err);
  43           return -1;
  44         }
  45     }
  46   return 0;
  47 }
  48 versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1);
  49
  50 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
  51
  52 int
  53 attribute_compat_text_section
  54 __old_sem_post (sem_t *sem)
  55 {
  56   int *futex = (int *) sem;
  57
  58   __asm __volatile (__lll_rel_instr ::: "memory");
  59   (void) atomic_increment_val (futex);
  60   /* We always have to assume it is a shared semaphore.  */
  61   int err = lll_futex_wake (futex, 1, LLL_SHARED);
  62   if (__builtin_expect (err, 0) < 0)
  63     {
  64       __set_errno (-err);
  65       return -1;
  66     }
  67   return 0;
  68 }
  69
  70 compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0);
  71 #endif