nptl/pthread_mutexattr_getprioceiling.c

   1 /* Get priority ceiling setting from pthread_mutexattr_t.
   2    Copyright (C) 2006-2015 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <pthreadP.h>
  21 #include <atomic.h>
  22
  23
  24 int
  25 pthread_mutexattr_getprioceiling (attr, prioceiling)
  26      const pthread_mutexattr_t *attr;
  27      int *prioceiling;
  28 {
  29   const struct pthread_mutexattr *iattr;
  30   int ceiling;
  31
  32   iattr = (const struct pthread_mutexattr *) attr;
  33
  34   ceiling = ((iattr->mutexkind & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  35              >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT);
  36
  37   if (! ceiling)
  38     {
  39       /* See __init_sched_fifo_prio.  */
  40       if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1)
  41         __init_sched_fifo_prio ();
  42       if (ceiling < atomic_load_relaxed (&__sched_fifo_min_prio))
  43         ceiling = atomic_load_relaxed (&__sched_fifo_min_prio);
  44     }
  45
  46   *prioceiling = ceiling;
  47
  48   return 0;
  49 }