sysdeps/unix/sysv/linux/lowlevellock-futex.h

   1 /* Low-level locking access to futex facilities.  Linux version.
   2    Copyright (C) 2005-2014 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 <sysdep.h>
  23 #include <tls.h>
  24 #include <kernel-features.h>
  25
  26
  27 #define FUTEX_WAIT              0
  28 #define FUTEX_WAKE              1
  29 #define FUTEX_REQUEUE           3
  30 #define FUTEX_CMP_REQUEUE       4
  31 #define FUTEX_WAKE_OP           5
  32 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
  33 #define FUTEX_LOCK_PI           6
  34 #define FUTEX_UNLOCK_PI         7
  35 #define FUTEX_TRYLOCK_PI        8
  36 #define FUTEX_WAIT_BITSET       9
  37 #define FUTEX_WAKE_BITSET       10
  38 #define FUTEX_WAIT_REQUEUE_PI   11
  39 #define FUTEX_CMP_REQUEUE_PI    12
  40 #define FUTEX_PRIVATE_FLAG      128
  41 #define FUTEX_CLOCK_REALTIME    256
  42
  43 #define FUTEX_BITSET_MATCH_ANY  0xffffffff
  44
  45 /* Values for 'private' parameter of locking macros.  Yes, the
  46    definition seems to be backwards.  But it is not.  The bit will be
  47    reversed before passing to the system call.  */
  48 #define LLL_PRIVATE     0
  49 #define LLL_SHARED      FUTEX_PRIVATE_FLAG
  50
  51
  52 #if !defined NOT_IN_libc || IS_IN (rtld)
  53 /* In libc.so or ld.so all futexes are private.  */
  54 # ifdef __ASSUME_PRIVATE_FUTEX
  55 #  define __lll_private_flag(fl, private) \
  56   ((fl) | FUTEX_PRIVATE_FLAG)
  57 # else
  58 #  define __lll_private_flag(fl, private) \
  59   ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
  60 # endif
  61 #else
  62 # ifdef __ASSUME_PRIVATE_FUTEX
  63 #  define __lll_private_flag(fl, private) \
  64   (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
  65 # else
  66 #  define __lll_private_flag(fl, private) \
  67   (__builtin_constant_p (private)                                             \
  68    ? ((private) == 0                                                          \
  69       ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))            \
  70       : (fl))                                                                 \
  71    : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG)                                \
  72               & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
  73 # endif
  74 #endif
  75
  76 #define lll_futex_syscall(nargs, futexp, op, ...)                       \
  77   ({                                                                    \
  78     INTERNAL_SYSCALL_DECL (__err);                                      \
  79     long int __ret = INTERNAL_SYSCALL (futex, __err, nargs, futexp, op, \
  80                                        __VA_ARGS__);                    \
  81     (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err))         \
  82      ? -INTERNAL_SYSCALL_ERRNO (__ret, __err) : 0);                     \
  83   })
  84
  85 #define lll_futex_wait(futexp, val, private) \
  86   lll_futex_timed_wait (futexp, val, NULL, private)
  87
  88 #define lll_futex_timed_wait(futexp, val, timeout, private)     \
  89   lll_futex_syscall (4, futexp,                                 \
  90                      __lll_private_flag (FUTEX_WAIT, private),  \
  91                      val, timeout)
  92
  93 #define lll_futex_timed_wait_bitset(futexp, val, timeout, clockbit, private) \
  94   lll_futex_syscall (6, futexp,                                         \
  95                      __lll_private_flag (FUTEX_WAIT_BITSET | (clockbit), \
  96                                          private),                      \
  97                      val, timeout, NULL /* Unused.  */,                 \
  98                      FUTEX_BITSET_MATCH_ANY)
  99
 100 #define lll_futex_wake(futexp, nr, private)                             \
 101   lll_futex_syscall (4, futexp,                                         \
 102                      __lll_private_flag (FUTEX_WAKE, private), nr, 0)
 103
 104 /* Returns non-zero if error happened, zero if success.  */
 105 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
 106   lll_futex_syscall (6, futexp,                                         \
 107                      __lll_private_flag (FUTEX_CMP_REQUEUE, private),   \
 108                      nr_wake, nr_move, mutex, val)
 109
 110 /* Returns non-zero if error happened, zero if success.  */
 111 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
 112   lll_futex_syscall (6, futexp,                                         \
 113                      __lll_private_flag (FUTEX_WAKE_OP, private),       \
 114                      nr_wake, nr_wake2, futexp2,                        \
 115                      FUTEX_OP_CLEAR_WAKE_IF_GT_ONE)
 116
 117 /* Priority Inheritance support.  */
 118 #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
 119   lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
 120
 121 #define lll_futex_timed_wait_requeue_pi(futexp, val, timeout, clockbit, \
 122                                         mutex, private)                 \
 123   lll_futex_syscall (5, futexp,                                         \
 124                      __lll_private_flag (FUTEX_WAIT_REQUEUE_PI          \
 125                                          | (clockbit), private),        \
 126                      val, timeout, mutex)
 127
 128
 129 #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex,       \
 130                                  val, private)                          \
 131   lll_futex_syscall (6, futexp,                                         \
 132                      __lll_private_flag (FUTEX_CMP_REQUEUE_PI,          \
 133                                          private),                      \
 134                      nr_wake, nr_move, mutex, val)
 135
 136
 137 #endif  /* lowlevellock-futex.h */