summary refs log tree commit diff
path: root/sysdeps/nptl/lowlevellock.h
blob: 28f4ba39780c1e6b64d1e9cf1a1cdb7e18fca7b0 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
/* Low-level lock implementation.  Generic futex-based version.
   Copyright (C) 2005-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef _LOWLEVELLOCK_H
#define _LOWLEVELLOCK_H	1

#include <atomic.h>
#include <lowlevellock-futex.h>

#define lll_trylock(lock)	\
  atomic_compare_and_exchange_bool_acq (&(lock), 1, 0)

#define lll_cond_trylock(lock)	\
  atomic_compare_and_exchange_bool_acq (&(lock), 2, 0)

extern void __lll_lock_wait_private (int *futex) attribute_hidden;
extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;

/* This is an expression rather than a statement even though its value is
   void, so that it can be used in a comma expression or as an expression
   that's cast to void.  */
#define __lll_lock(futex, private)                                      \
  ((void)                                                               \
   ({                                                                   \
     int *__futex = (futex);                                            \
     if (__glibc_unlikely                                               \
         (atomic_compare_and_exchange_bool_acq (__futex, 1, 0)))        \
       {                                                                \
         if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
           __lll_lock_wait_private (__futex);                           \
         else                                                           \
           __lll_lock_wait (__futex, private);                          \
       }                                                                \
   }))
#define lll_lock(futex, private)	\
  __lll_lock (&(futex), private)


#define __lll_robust_lock(futex, id, private)                           \
  ({                                                                    \
    int *__futex = (futex);                                             \
    int __val = 0;                                                      \
                                                                        \
    if (__glibc_unlikely                                                \
        (atomic_compare_and_exchange_bool_acq (__futex, id, 0)))        \
      __val = __lll_robust_lock_wait (__futex, private);                \
    __val;                                                              \
  })
#define lll_robust_lock(futex, id, private)     \
  __lll_robust_lock (&(futex), id, private)


/* This is an expression rather than a statement even though its value is
   void, so that it can be used in a comma expression or as an expression
   that's cast to void.  */
#define __lll_cond_lock(futex, private)                                 \
  ((void)                                                               \
   ({                                                                   \
     int *__futex = (futex);                                            \
     if (__glibc_unlikely (atomic_exchange_acq (__futex, 2) != 0))      \
       __lll_lock_wait (__futex, private);                              \
   }))
#define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)


#define lll_robust_cond_lock(futex, id, private)	\
  __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)


extern int __lll_timedlock_wait (int *futex, const struct timespec *,
				 int private) attribute_hidden;
extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
					int private) attribute_hidden;

/* Take futex if it is untaken.
   Otherwise block until either we get the futex or abstime runs out.  */
#define __lll_timedlock(futex, abstime, private)                \
  ({                                                            \
    int *__futex = (futex);                                     \
    int __val = 0;                                              \
                                                                \
    if (__glibc_unlikely                                        \
        (atomic_compare_and_exchange_bool_acq (__futex, 1, 0))) \
      __val = __lll_timedlock_wait (__futex, abstime, private); \
    __val;                                                      \
  })
#define lll_timedlock(futex, abstime, private)  \
  __lll_timedlock (&(futex), abstime, private)


#define __lll_robust_timedlock(futex, abstime, id, private)             \
  ({                                                                    \
    int *__futex = (futex);                                             \
    int __val = 0;                                                      \
                                                                        \
    if (__glibc_unlikely                                                \
        (atomic_compare_and_exchange_bool_acq (__futex, id, 0)))        \
      __val = __lll_robust_timedlock_wait (__futex, abstime, private);  \
    __val;                                                              \
  })
#define lll_robust_timedlock(futex, abstime, id, private)       \
  __lll_robust_timedlock (&(futex), abstime, id, private)


/* This is an expression rather than a statement even though its value is
   void, so that it can be used in a comma expression or as an expression
   that's cast to void.  */
#define __lll_unlock(futex, private)                    \
  ((void)                                               \
   ({                                                   \
     int *__futex = (futex);                            \
     int __oldval = atomic_exchange_rel (__futex, 0);   \
     if (__glibc_unlikely (__oldval > 1))               \
       lll_futex_wake (__futex, 1, private);            \
   }))
#define lll_unlock(futex, private)	\
  __lll_unlock (&(futex), private)


/* This is an expression rather than a statement even though its value is
   void, so that it can be used in a comma expression or as an expression
   that's cast to void.  */
#define __lll_robust_unlock(futex, private)             \
  ((void)                                               \
   ({                                                   \
     int *__futex = (futex);                            \
     int __oldval = atomic_exchange_rel (__futex, 0);   \
     if (__glibc_unlikely (__oldval & FUTEX_WAITERS))	\
       lll_futex_wake (__futex, 1, private);            \
   }))
#define lll_robust_unlock(futex, private)       \
  __lll_robust_unlock (&(futex), private)


#define lll_islocked(futex) \
  ((futex) != LLL_LOCK_INITIALIZER)


/* Our internal lock implementation is identical to the binary-compatible
   mutex implementation. */

/* Initializers for lock.  */
#define LLL_LOCK_INITIALIZER		(0)
#define LLL_LOCK_INITIALIZER_LOCKED	(1)

/* The states of a lock are:
    0  -  untaken
    1  -  taken by one user
   >1  -  taken by more users */

/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
   wakeup when the clone terminates.  The memory location contains the
   thread ID while the clone is running and is reset to zero
   afterwards.	*/
#define lll_wait_tid(tid) \
  do {					\
    __typeof (tid) __tid;		\
    while ((__tid = (tid)) != 0)	\
      lll_futex_wait (&(tid), __tid, LLL_SHARED);\
  } while (0)

extern int __lll_timedwait_tid (int *, const struct timespec *)
     attribute_hidden;

#define lll_timedwait_tid(tid, abstime) \
  ({							\
    int __res = 0;					\
    if ((tid) != 0)					\
      __res = __lll_timedwait_tid (&(tid), (abstime));	\
    __res;						\
  })


#endif	/* lowlevellock.h */