nptl/pthread_mutex_setprioceiling.c

   1 /* Set current priority ceiling of pthread_mutex_t.
   2    Copyright (C) 2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Jakub Jelinek <jakub@redhat.com>, 2006.
   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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <pthreadP.h>
  23
  24
  25 int
  26 pthread_mutex_setprioceiling (mutex, prioceiling, old_ceiling)
  27      pthread_mutex_t *mutex;
  28      int prioceiling;
  29      int *old_ceiling;
  30 {
  31   /* The low bits of __kind aren't ever changed after pthread_mutex_init,
  32      so we don't need a lock yet.  */
  33   if ((mutex->__data.__kind & PTHREAD_MUTEX_PRIO_PROTECT_PRIVATE_NP) == 0)
  34     return EINVAL;
  35
  36   if (prioceiling < 0 || __builtin_expect (prioceiling > 255, 0))
  37     return EINVAL;
  38
  39   /* XXX This needs to lock with TID, but shouldn't obey priority protect
  40      protocol.  */
  41   /* lll_xxx_mutex_lock (mutex->__data.__lock); */
  42
  43   if (old_ceiling != NULL)
  44     *old_ceiling = (mutex->__data.__kind & PTHREAD_MUTEX_PRIO_CEILING_MASK)
  45                    >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
  46
  47   int newkind = (mutex->__data.__kind & ~PTHREAD_MUTEX_PRIO_CEILING_MASK);
  48   mutex->__data.__kind = newkind
  49                          | (prioceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT);
  50
  51   /* XXX This needs to unlock the above special kind of lock.  */
  52   /* lll_xxx_mutex_unlock (mutex->__data.__lock); */
  53
  54   return 0;
  55 }