nptl/pthread_mutex_init.c

   1 /* Copyright (C) 2002, 2003, 2004, 2005, 2006 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <string.h>
  23 #include "pthreadP.h"
  24
  25 static const struct pthread_mutexattr default_attr =
  26   {
  27     /* Default is a normal mutex, not shared between processes.  */
  28     .mutexkind = PTHREAD_MUTEX_NORMAL
  29   };
  30
  31
  32 int
  33 __pthread_mutex_init (mutex, mutexattr)
  34      pthread_mutex_t *mutex;
  35      const pthread_mutexattr_t *mutexattr;
  36 {
  37   const struct pthread_mutexattr *imutexattr;
  38
  39   assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T);
  40
  41   imutexattr = (const struct pthread_mutexattr *) mutexattr ?: &default_attr;
  42
  43   /* Sanity checks.  */
  44   // XXX For now we don't support priority inherited or priority protected
  45   // XXX mutexes.
  46   switch (__builtin_expect (imutexattr->mutexkind
  47                             & PTHREAD_MUTEXATTR_PROTOCOL_MASK,
  48                             PTHREAD_PRIO_NONE
  49                             << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
  50     {
  51     case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
  52       break;
  53
  54     default:
  55       return ENOTSUP;
  56     }
  57
  58   /* Clear the whole variable.  */
  59   memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
  60
  61   /* Copy the values from the attribute.  */
  62   mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
  63
  64   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
  65     {
  66 #ifndef __ASSUME_SET_ROBUST_LIST
  67       if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
  68           && __set_robust_list_avail < 0)
  69         return ENOTSUP;
  70 #endif
  71
  72       mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
  73     }
  74
  75   switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
  76     {
  77     case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
  78       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_PRIVATE_NP;
  79       break;
  80
  81     case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
  82       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_PRIVATE_NP;
  83       if (PTHREAD_MUTEX_PRIO_CEILING_MASK
  84           == PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  85         mutex->__data.__kind |= (imutexattr->mutexkind
  86                                  & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK);
  87       else
  88         mutex->__data.__kind |= ((imutexattr->mutexkind
  89                                   & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  90                                  >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT)
  91                                 << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
  92       break;
  93
  94     default:
  95       break;
  96     }
  97
  98   /* Default values: mutex not used yet.  */
  99   // mutex->__count = 0;        already done by memset
 100   // mutex->__owner = 0;        already done by memset
 101   // mutex->__nusers = 0;       already done by memset
 102   // mutex->__spins = 0;        already done by memset
 103   // mutex->__next = NULL;      already done by memset
 104
 105   return 0;
 106 }
 107 strong_alias (__pthread_mutex_init, pthread_mutex_init)
 108 INTDEF(__pthread_mutex_init)