sysdeps/nptl/lowlevellock-futex.h

   1 /* Low-level locking access to futex facilities.  Stub version.
   2    Copyright (C) 2014-2019 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _LOWLEVELLOCK_FUTEX_H
  20 #define _LOWLEVELLOCK_FUTEX_H   1
  21
  22 #include <errno.h>
  23
  24
  25 /* Values for 'private' parameter of locking macros.  Note pthreadP.h
  26    optimizes for these exact values, though they are not required.  */
  27 #define LLL_PRIVATE     0
  28 #define LLL_SHARED      128
  29
  30
  31 /* For most of these macros, the return value is never really used.
  32    Nevertheless, the protocol is that each one returns a negated errno
  33    code for failure or zero for success.  (Note that the corresponding
  34    Linux system calls can sometimes return positive values for success
  35    cases too.  We never use those values.)  */
  36
  37
  38 /* Wait while *FUTEXP == VAL for an lll_futex_wake call on FUTEXP.  */
  39 #define lll_futex_wait(futexp, val, private) \
  40   lll_futex_timed_wait (futexp, val, NULL, private)
  41
  42 /* Wait until a lll_futex_wake call on FUTEXP, or TIMEOUT elapses.  */
  43 #define lll_futex_timed_wait(futexp, val, timeout, private)             \
  44   -ENOSYS
  45
  46 /* Verify whether the supplied clockid is supported by
  47    lll_futex_clock_wait_bitset.  */
  48 #define lll_futex_supported_clockid(clockid)                            \
  49   (0)
  50
  51 /* Wait until a lll_futex_wake call on FUTEXP, or the absolute TIMEOUT
  52    measured against CLOCKID elapses. CLOCKID may be CLOCK_REALTIME or
  53    CLOCK_MONOTONIC.  */
  54 #define lll_futex_clock_wait_bitset(futexp, val, clockid, timeout, private) \
  55   -ENOSYS
  56
  57 /* Wake up up to NR waiters on FUTEXP.  */
  58 #define lll_futex_wake(futexp, nr, private)                             \
  59   -ENOSYS
  60
  61 /* Wake up up to NR_WAKE waiters on FUTEXP.  Move up to NR_MOVE of the
  62    rest from waiting on FUTEXP to waiting on MUTEX (a different futex).  */
  63 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
  64   -ENOSYS
  65
  66 /* Wake up up to NR_WAKE waiters on FUTEXP and NR_WAKE2 on FUTEXP2.  */
  67 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
  68   -ENOSYS
  69
  70
  71 /* Like lll_futex_wait (FUTEXP, VAL, PRIVATE) but with the expectation
  72    that lll_futex_cmp_requeue_pi (FUTEXP, _, _, MUTEX, _, PRIVATE) will
  73    be used to do the wakeup.  Confers priority-inheritance behavior on
  74    the waiter.  */
  75 #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
  76   lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
  77
  78 /* Like lll_futex_wait_requeue_pi, but with a timeout.  */
  79 #define lll_futex_timed_wait_requeue_pi(futexp, val, timeout, clockbit, \
  80                                         mutex, private)                 \
  81   -ENOSYS
  82
  83 /* Like lll_futex_requeue, but pairs with lll_futex_wait_requeue_pi
  84    and inherits priority from the waiter.  */
  85 #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex,       \
  86                                  val, private)                          \
  87   -ENOSYS
  88
  89 /* Like lll_futex_wait, but acting as a cancellable entrypoint.  */
  90 #define lll_futex_wait_cancel(futexp, val, private) \
  91   -ENOSYS
  92
  93 /* Like lll_futex_timed_wait, but acting as a cancellable entrypoint.  */
  94 #define lll_futex_timed_wait_cancel(futexp, val, timeout, private) \
  95   -ENOSYS
  96
  97 #endif  /* lowlevellock-futex.h */