nptl/sem_init.c

   1 /* Copyright (C) 2002-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <semaphore.h>
  21 #include <shlib-compat.h>
  22 #include "semaphoreP.h"
  23 #include <kernel-features.h>
  24
  25 /* Returns FUTEX_PRIVATE if pshared is zero and private futexes are supported;
  26    returns FUTEX_SHARED otherwise.
  27    TODO Remove when cleaning up the futex API throughout glibc.  */
  28 static __always_inline int
  29 futex_private_if_supported (int pshared)
  30 {
  31   if (pshared != 0)
  32     return LLL_SHARED;
  33 #ifdef __ASSUME_PRIVATE_FUTEX
  34   return LLL_PRIVATE;
  35 #else
  36   return THREAD_GETMEM (THREAD_SELF, header.private_futex)
  37       ^ FUTEX_PRIVATE_FLAG;
  38 #endif
  39 }
  40
  41
  42 int
  43 __new_sem_init (sem_t *sem, int pshared, unsigned int value)
  44 {
  45   /* Parameter sanity check.  */
  46   if (__glibc_unlikely (value > SEM_VALUE_MAX))
  47     {
  48       __set_errno (EINVAL);
  49       return -1;
  50     }
  51
  52   /* Map to the internal type.  */
  53   struct new_sem *isem = (struct new_sem *) sem;
  54
  55   /* Use the values the caller provided.  */
  56 #if __HAVE_64B_ATOMICS
  57   isem->data = value;
  58 #else
  59   isem->value = value << SEM_VALUE_SHIFT;
  60   isem->nwaiters = 0;
  61 #endif
  62
  63   isem->private = futex_private_if_supported (pshared);
  64
  65   return 0;
  66 }
  67 versioned_symbol (libpthread, __new_sem_init, sem_init, GLIBC_2_1);
  68
  69
  70
  71 #if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
  72 int
  73 attribute_compat_text_section
  74 __old_sem_init (sem, pshared, value)
  75      sem_t *sem;
  76      int pshared;
  77      unsigned int value;
  78 {
  79   /* Parameter sanity check.  */
  80   if (__glibc_unlikely (value > SEM_VALUE_MAX))
  81     {
  82       __set_errno (EINVAL);
  83       return -1;
  84     }
  85
  86   /* Map to the internal type.  */
  87   struct old_sem *isem = (struct old_sem *) sem;
  88
  89   /* Use the value the user provided.  */
  90   isem->value = value;
  91
  92   /* We cannot store the PSHARED attribute.  So we always use the
  93      operations needed for shared semaphores.  */
  94
  95   return 0;
  96 }
  97 compat_symbol (libpthread, __old_sem_init, sem_init, GLIBC_2_0);
  98 #endif