nptl/pthread_mutexattr_getprioceiling.c

   1 /* Get priority ceiling setting from pthread_mutexattr_t.
   2    Copyright (C) 2006-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <pthreadP.h>
  20 #include <atomic.h>
  21 #include <shlib-compat.h>
  22
  23 int
  24 __pthread_mutexattr_getprioceiling (const pthread_mutexattr_t *attr,
  25                                     int *prioceiling)
  26 {
  27   const struct pthread_mutexattr *iattr;
  28   int ceiling;
  29
  30   iattr = (const struct pthread_mutexattr *) attr;
  31
  32   ceiling = ((iattr->mutexkind & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
  33              >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT);
  34
  35   if (! ceiling)
  36     {
  37       /* See __init_sched_fifo_prio.  */
  38       if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1)
  39         __init_sched_fifo_prio ();
  40       if (ceiling < atomic_load_relaxed (&__sched_fifo_min_prio))
  41         ceiling = atomic_load_relaxed (&__sched_fifo_min_prio);
  42     }
  43
  44   *prioceiling = ceiling;
  45
  46   return 0;
  47 }
  48 versioned_symbol (libc, __pthread_mutexattr_getprioceiling,
  49                   pthread_mutexattr_getprioceiling, GLIBC_2_34);
  50
  51 #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_4, GLIBC_2_34)
  52 compat_symbol (libpthread, __pthread_mutexattr_getprioceiling,
  53                pthread_mutexattr_getprioceiling, GLIBC_2_4);
  54 #endif