support/support_mutex_pi_monotonic.c

   1 /* Returns whether Priority Inheritance support CLOCK_MONOTONIC.
   2    Copyright (C) 2021-2022 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 <support/xthread.h>
  20 #include <sys/syscall.h>
  21 #include <unistd.h>
  22
  23 bool
  24 support_mutex_pi_monotonic (void)
  25 {
  26 #ifdef __linux__
  27 # ifndef __NR_futex
  28 #  define __NR_futex __NR_futex_time64
  29 # endif
  30   int r = syscall (__NR_futex, &(unsigned int){0}, 13 /* FUTEX_LOCK_PI2  */,
  31                    0, NULL);
  32   return r == 0;
  33 #else
  34   return false;
  35 #endif
  36 }