1 /* Copyright (C) 2005-2014 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
19 #ifndef _LOWLEVELLOCK_H
20 #define _LOWLEVELLOCK_H 1
23 #include <sys/param.h>
24 #include <bits/pthreadtypes.h>
27 #include <kernel-features.h>
31 #define FUTEX_REQUEUE 3
32 #define FUTEX_CMP_REQUEUE 4
33 #define FUTEX_WAKE_OP 5
34 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE ((4 << 24) | 1)
35 #define FUTEX_LOCK_PI 6
36 #define FUTEX_UNLOCK_PI 7
37 #define FUTEX_TRYLOCK_PI 8
38 #define FUTEX_WAIT_BITSET 9
39 #define FUTEX_WAKE_BITSET 10
40 #define FUTEX_WAIT_REQUEUE_PI 11
41 #define FUTEX_CMP_REQUEUE_PI 12
42 #define FUTEX_PRIVATE_FLAG 128
43 #define FUTEX_CLOCK_REALTIME 256
45 #define FUTEX_BITSET_MATCH_ANY 0xffffffff
47 /* Values for 'private' parameter of locking macros. Yes, the
48 definition seems to be backwards. But it is not. The bit will be
49 reversed before passing to the system call. */
51 #define LLL_SHARED FUTEX_PRIVATE_FLAG
54 #if !defined NOT_IN_libc || defined IS_IN_rtld
55 /* In libc.so or ld.so all futexes are private. */
56 # ifdef __ASSUME_PRIVATE_FUTEX
57 # define __lll_private_flag(fl, private) \
58 ((fl) | FUTEX_PRIVATE_FLAG)
60 # define __lll_private_flag(fl, private) \
61 ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
64 # ifdef __ASSUME_PRIVATE_FUTEX
65 # define __lll_private_flag(fl, private) \
66 (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
68 # define __lll_private_flag(fl, private) \
69 (__builtin_constant_p (private) \
71 ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex)) \
73 : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG) \
74 & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
79 #define lll_futex_wait(futexp, val, private) \
80 lll_futex_timed_wait(futexp, val, NULL, private)
82 #define lll_futex_timed_wait(futexp, val, timespec, private) \
84 INTERNAL_SYSCALL_DECL (__err); \
86 __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp), \
87 __lll_private_flag (FUTEX_WAIT, private), \
92 #define lll_futex_timed_wait_bitset(futexp, val, timespec, clockbit, private) \
94 INTERNAL_SYSCALL_DECL (__err); \
96 int __op = FUTEX_WAIT_BITSET | clockbit; \
97 __ret = INTERNAL_SYSCALL (futex, __err, 6, (long) (futexp), \
98 __lll_private_flag (__op, private), \
99 (val), (timespec), NULL /* Unused. */, \
100 FUTEX_BITSET_MATCH_ANY); \
104 #define lll_futex_wake(futexp, nr, private) \
106 INTERNAL_SYSCALL_DECL (__err); \
108 __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp), \
109 __lll_private_flag (FUTEX_WAKE, private), \
114 #define lll_robust_dead(futexv, private) \
117 int *__futexp = &(futexv); \
118 atomic_or (__futexp, FUTEX_OWNER_DIED); \
119 lll_futex_wake (__futexp, 1, private); \
123 /* Returns non-zero if error happened, zero if success. */
124 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
126 INTERNAL_SYSCALL_DECL (__err); \
128 __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp), \
129 __lll_private_flag (FUTEX_CMP_REQUEUE, private),\
130 (nr_wake), (nr_move), (mutex), (val)); \
131 INTERNAL_SYSCALL_ERROR_P (__ret, __err); \
135 /* Returns non-zero if error happened, zero if success. */
136 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
138 INTERNAL_SYSCALL_DECL (__err); \
140 __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp), \
141 __lll_private_flag (FUTEX_WAKE_OP, private), \
142 (nr_wake), (nr_wake2), (futexp2), \
143 FUTEX_OP_CLEAR_WAKE_IF_GT_ONE); \
144 INTERNAL_SYSCALL_ERROR_P (__ret, __err); \
148 /* Priority Inheritance support. */
149 #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
150 lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
152 #define lll_futex_timed_wait_requeue_pi(futexp, val, timespec, clockbit, \
155 INTERNAL_SYSCALL_DECL (__err); \
157 int __op = FUTEX_WAIT_REQUEUE_PI | clockbit; \
159 __ret = INTERNAL_SYSCALL (futex, __err, 5, (futexp), \
160 __lll_private_flag (__op, private), \
161 (val), (timespec), mutex); \
162 INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret; \
165 #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, val, priv) \
167 INTERNAL_SYSCALL_DECL (__err); \
170 __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp), \
171 __lll_private_flag (FUTEX_CMP_REQUEUE_PI, priv),\
172 (nr_wake), (nr_move), (mutex), (val)); \
173 INTERNAL_SYSCALL_ERROR_P (__ret, __err); \
177 #define lll_trylock(lock) \
178 atomic_compare_and_exchange_val_acq(&(lock), 1, 0)
180 #define lll_cond_trylock(lock) \
181 atomic_compare_and_exchange_val_acq(&(lock), 2, 0)
183 #define __lll_robust_trylock(futex, id) \
184 (atomic_compare_and_exchange_val_acq (futex, id, 0) != 0)
185 #define lll_robust_trylock(lock, id) \
186 __lll_robust_trylock (&(lock), id)
188 extern void __lll_lock_wait_private (int *futex
) attribute_hidden
;
189 extern void __lll_lock_wait (int *futex
, int private) attribute_hidden
;
190 extern int __lll_robust_lock_wait (int *futex
, int private) attribute_hidden
;
192 #define __lll_lock(futex, private) \
194 int *__futex = (futex); \
195 if (__builtin_expect (atomic_compare_and_exchange_val_acq (__futex, \
198 if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
199 __lll_lock_wait_private (__futex); \
201 __lll_lock_wait (__futex, private); \
204 #define lll_lock(futex, private) __lll_lock (&(futex), private)
207 #define __lll_robust_lock(futex, id, private) \
209 int *__futex = (futex); \
212 if (__builtin_expect (atomic_compare_and_exchange_bool_acq (__futex, id, \
214 __val = __lll_robust_lock_wait (__futex, private); \
217 #define lll_robust_lock(futex, id, private) \
218 __lll_robust_lock (&(futex), id, private)
221 #define __lll_cond_lock(futex, private) \
223 int *__futex = (futex); \
224 if (__builtin_expect (atomic_exchange_acq (__futex, 2), 0)) \
225 __lll_lock_wait (__futex, private); \
227 #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
230 #define lll_robust_cond_lock(futex, id, private) \
231 __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)
234 extern int __lll_timedlock_wait (int *futex
, const struct timespec
*,
235 int private) attribute_hidden
;
236 extern int __lll_robust_timedlock_wait (int *futex
, const struct timespec
*,
237 int private) attribute_hidden
;
239 #define __lll_timedlock(futex, abstime, private) \
241 int *__futex = (futex); \
244 if (__builtin_expect (atomic_exchange_acq (__futex, 1), 0)) \
245 __val = __lll_timedlock_wait (__futex, abstime, private); \
248 #define lll_timedlock(futex, abstime, private) \
249 __lll_timedlock (&(futex), abstime, private)
252 #define __lll_robust_timedlock(futex, abstime, id, private) \
254 int *__futex = (futex); \
257 if (__builtin_expect (atomic_compare_and_exchange_bool_acq (__futex, id, \
259 __val = __lll_robust_timedlock_wait (__futex, abstime, private); \
262 #define lll_robust_timedlock(futex, abstime, id, private) \
263 __lll_robust_timedlock (&(futex), abstime, id, private)
266 #define __lll_unlock(futex, private) \
268 ({ int *__futex = (futex); \
269 int __oldval = atomic_exchange_rel (__futex, 0); \
270 if (__builtin_expect (__oldval > 1, 0)) \
271 lll_futex_wake (__futex, 1, private); \
274 #define lll_unlock(futex, private) __lll_unlock(&(futex), private)
277 #define __lll_robust_unlock(futex, private) \
279 ({ int *__futex = (futex); \
280 int __oldval = atomic_exchange_rel (__futex, 0); \
281 if (__builtin_expect (__oldval & FUTEX_WAITERS, 0)) \
282 lll_futex_wake (__futex, 1, private); \
284 #define lll_robust_unlock(futex, private) \
285 __lll_robust_unlock(&(futex), private)
288 #define lll_islocked(futex) \
292 /* Our internal lock implementation is identical to the binary-compatible
293 mutex implementation. */
295 /* Initializers for lock. */
296 #define LLL_LOCK_INITIALIZER (0)
297 #define LLL_LOCK_INITIALIZER_LOCKED (1)
299 /* The states of a lock are:
301 1 - taken by one user
302 >1 - taken by more users */
304 /* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
305 wakeup when the clone terminates. The memory location contains the
306 thread ID while the clone is running and is reset to zero
308 #define lll_wait_tid(tid) \
310 __typeof (tid) __tid; \
311 while ((__tid = (tid)) != 0) \
312 lll_futex_wait (&(tid), __tid, LLL_SHARED);\
315 extern int __lll_timedwait_tid (int *, const struct timespec
*)
318 #define lll_timedwait_tid(tid, abstime) \
322 __res = __lll_timedwait_tid (&(tid), (abstime)); \
326 #endif /* lowlevellock.h */