glibc/nptl/pthread_mutex_setprioceiling.c

/* Set current priority ceiling of pthread_mutex_t.
   Copyright (C) 2006 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Jakub Jelinek <jakub@redhat.com>, 2006.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <pthreadP.h>


int
pthread_mutex_setprioceiling (mutex, prioceiling, old_ceiling)
     pthread_mutex_t *mutex;
     int prioceiling;
     int *old_ceiling;
{
  /* The low bits of __kind aren't ever changed after pthread_mutex_init,
     so we don't need a lock yet.  */
  if ((mutex->__data.__kind & PTHREAD_MUTEX_PRIO_PROTECT_NP) == 0)
    return EINVAL;

  if (prioceiling < 0 || __builtin_expect (prioceiling > 255, 0))
    return EINVAL;

  /* XXX This needs to lock with TID, but shouldn't obey priority protect
     protocol.  */
  /* lll_xxx_mutex_lock (mutex->__data.__lock); */

  if (old_ceiling != NULL)
    *old_ceiling = (mutex->__data.__kind & PTHREAD_MUTEX_PRIO_CEILING_MASK)
		   >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;

  int newkind = (mutex->__data.__kind & ~PTHREAD_MUTEX_PRIO_CEILING_MASK);
  mutex->__data.__kind = newkind
			 | (prioceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT);

  /* XXX This needs to unlock the above special kind of lock.  */
  /* lll_xxx_mutex_unlock (mutex->__data.__lock); */

  return 0;
}