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
  26 static const struct pthread_mutexattr default_attr =
  27   {
  28     /* Default is a normal mutex, not shared between processes.  */
  29     .mutexkind = PTHREAD_MUTEX_NORMAL
  30   };
  31
  32
  33 int
  34 __pthread_mutex_init (mutex, mutexattr)
  35      pthread_mutex_t *mutex;
  36      const pthread_mutexattr_t *mutexattr;
  37 {
  38   const struct pthread_mutexattr *imutexattr;
  39
  40   assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T);
  41
  42   imutexattr = (const struct pthread_mutexattr *) mutexattr ?: &default_attr;
  43
  44   /* Sanity checks.  */
  45   // XXX For now we cannot implement robust mutexes if they are shared.
  46   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0
  47       && (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0)
  48     return ENOTSUP;
  49   // XXX For now we don't support priority inherited or priority protected
  50   // XXX mutexes.
  51   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
  52       != (PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
  53     return ENOTSUP;
  54
  55   /* Clear the whole variable.  */
  56   memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
  57
  58   /* Copy the values from the attribute.  */
  59   mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
  60   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
  61     mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_PRIVATE_NP;
  62   switch ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
  63           >> PTHREAD_MUTEXATTR_PROTOCOL_SHIFT)
  64     {
  65     case PTHREAD_PRIO_INHERIT:
  66       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_PRIVATE_NP;
  67       break;
  68     case PTHREAD_PRIO_PROTECT:
  69       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_PRIVATE_NP;
  70       if (PTHREAD_MUTEX_PRIO_CEILING_MASK
  71           == PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  72         mutex->__data.__kind |= (imutexattr->mutexkind
  73                                  & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK);
  74       else
  75         mutex->__data.__kind |= ((imutexattr->mutexkind
  76                                   & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  77                                  >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT)
  78                                 << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
  79       break;
  80     default:
  81       break;
  82     }
  83
  84   /* Default values: mutex not used yet.  */
  85   // mutex->__count = 0;        already done by memset
  86   // mutex->__owner = 0;        already done by memset
  87   // mutex->__nusers = 0;       already done by memset
  88   // mutex->__spins = 0;        already done by memset
  89   // mutex->__next = NULL;      already done by memset
  90
  91   return 0;
  92 }
  93 strong_alias (__pthread_mutex_init, pthread_mutex_init)
  94 INTDEF(__pthread_mutex_init)