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   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
  47       != (PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
  48     return ENOTSUP;
  49
  50   /* Clear the whole variable.  */
  51   memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
  52
  53   /* Copy the values from the attribute.  */
  54   mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
  55
  56   if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
  57     {
  58 #ifndef __ASSUME_SET_ROBUST_LIST
  59       if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
  60           && __set_robust_list_avail < 0)
  61         return ENOTSUP;
  62 #endif
  63
  64       mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
  65     }
  66
  67   switch ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
  68           >> PTHREAD_MUTEXATTR_PROTOCOL_SHIFT)
  69     {
  70     case PTHREAD_PRIO_INHERIT:
  71       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_PRIVATE_NP;
  72       break;
  73     case PTHREAD_PRIO_PROTECT:
  74       mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_PRIVATE_NP;
  75       if (PTHREAD_MUTEX_PRIO_CEILING_MASK
  76           == PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  77         mutex->__data.__kind |= (imutexattr->mutexkind
  78                                  & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK);
  79       else
  80         mutex->__data.__kind |= ((imutexattr->mutexkind
  81                                   & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  82                                  >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT)
  83                                 << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
  84       break;
  85     default:
  86       break;
  87     }
  88
  89   /* Default values: mutex not used yet.  */
  90   // mutex->__count = 0;        already done by memset
  91   // mutex->__owner = 0;        already done by memset
  92   // mutex->__nusers = 0;       already done by memset
  93   // mutex->__spins = 0;        already done by memset
  94   // mutex->__next = NULL;      already done by memset
  95
  96   return 0;
  97 }
  98 strong_alias (__pthread_mutex_init, pthread_mutex_init)
  99 INTDEF(__pthread_mutex_init)