glibc/nptl/pthread_mutexattr_setprioceiling.c

/* Change priority ceiling setting in pthread_mutexattr_t.
   Copyright (C) 2006-2018 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, see
   <http://www.gnu.org/licenses/>.  */

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


int
pthread_mutexattr_setprioceiling (pthread_mutexattr_t *attr, int prioceiling)
{
  /* See __init_sched_fifo_prio.  */
  if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1
      || atomic_load_relaxed (&__sched_fifo_max_prio) == -1)
    __init_sched_fifo_prio ();

  if (__glibc_unlikely (prioceiling
			< atomic_load_relaxed (&__sched_fifo_min_prio))
      || __glibc_unlikely (prioceiling
			   > atomic_load_relaxed (&__sched_fifo_max_prio))
      || __glibc_unlikely ((prioceiling
			    & (PTHREAD_MUTEXATTR_PRIO_CEILING_MASK
			       >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT))
			   != prioceiling))
    return EINVAL;

  struct pthread_mutexattr *iattr = (struct pthread_mutexattr *) attr;

  iattr->mutexkind = ((iattr->mutexkind & ~PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
		      | (prioceiling << PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT));

  return 0;
}