sysdeps/nacl/lowlevellock-futex.h

   1 /* Low-level locking access to futex facilities.  NaCl version.
   2    Copyright (C) 2015-2016 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 <nacl-interfaces.h>
  23 #include <time.h>
  24
  25
  26 #pragma GCC diagnostic ignored "-Wunused-value" /* XXX */
  27
  28 /* Values for 'private' parameter of locking macros.  Note pthreadP.h
  29    optimizes for these exact values, though they are not required.  */
  30 #define LLL_PRIVATE     0
  31 #define LLL_SHARED      128
  32
  33 #define FUTEX_PRIVATE_FLAG      0       /* XXX */
  34
  35
  36 /* Wait while *FUTEXP == VAL for an lll_futex_wake call on FUTEXP.  */
  37 #define lll_futex_wait(futexp, val, private) \
  38   ((void) (private), \
  39    - __nacl_irt_futex.futex_wait_abs ((volatile int *) (futexp), val, NULL))
  40
  41 /* Wait until a lll_futex_wake call on FUTEXP, or TIMEOUT elapses.  */
  42 #define lll_futex_timed_wait(futexp, val, timeout, private)             \
  43   ({                                                                    \
  44     /* This timeout is relative, but the IRT call wants it absolute.  */\
  45     const struct timespec *_to = (timeout);                             \
  46     struct timespec _ts;                                                \
  47     int _err = 0;                                                       \
  48     if (_to != NULL                                                     \
  49         && __glibc_likely ((_err = __nacl_irt_clock.clock_gettime       \
  50                             (CLOCK_REALTIME, &_ts)) == 0))              \
  51       {                                                                 \
  52         _ts.tv_sec += _to->tv_sec;                                      \
  53         _ts.tv_nsec += _to->tv_nsec;                                    \
  54         while (_ts.tv_nsec >= 1000000000)                               \
  55           {                                                             \
  56             _ts.tv_nsec -= 1000000000;                                  \
  57             ++_ts.tv_sec;                                               \
  58           }                                                             \
  59         _to = &_ts;                                                     \
  60       }                                                                 \
  61     if (_err == 0)                                                      \
  62       _err = __nacl_irt_futex.futex_wait_abs                            \
  63         ((volatile int *) (futexp), val, _to);                          \
  64     (void) (private);                                                   \
  65     -_err;                                                              \
  66   })
  67
  68 /* Wake up up to NR waiters on FUTEXP.  */
  69 #define lll_futex_wake(futexp, nr, private)                     \
  70   ({                                                            \
  71     int _woken;                                                 \
  72     (void) (private);                                           \
  73     - __nacl_irt_futex.futex_wake ((volatile int *) (futexp), nr, &_woken); \
  74   })
  75
  76 /* NaCl does not support the requeue operation.  The only use of this is in
  77    pthread_cond_broadcast, which handles an error return by falling back to
  78    plain lll_futex_wake.  */
  79 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
  80   ((futexp), (nr_wake), (nr_move), (mutex), (val), (private), -ENOSYS)
  81
  82 /* NaCl does not support the special wake-unlock operation.  The only use
  83    of this is in pthread_cond_signal, which handles an error return by
  84    falling back to plain lll_futex_wake.  */
  85 /* Wake up up to NR_WAKE waiters on FUTEXP and NR_WAKE2 on FUTEXP2.  */
  86 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
  87   ((futexp), (nr_wake), (nr_wake2), (futexp2), (private), -ENOSYS)
  88
  89
  90 #endif  /* lowlevellock-futex.h */