1/* low level locking for pthread library. Generic futex-using version.
2 Copyright (C) 2003-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <sysdep.h>
21#include <futex-internal.h>
22#include <atomic.h>
23#include <stap-probe.h>
24
25void
26__lll_lock_wait_private (int *futex)
27{
28 if (atomic_load_relaxed (futex) == 2)
29 goto futex;
30
31 while (atomic_exchange_acquire (futex, 2) != 0)
32 {
33 futex:
34 LIBC_PROBE (lll_lock_wait_private, 1, futex);
35 futex_wait ((unsigned int *) futex, 2, LLL_PRIVATE); /* Wait if *futex == 2. */
36 }
37}
38libc_hidden_def (__lll_lock_wait_private)
39
40void
41__lll_lock_wait (int *futex, int private)
42{
43 if (atomic_load_relaxed (futex) == 2)
44 goto futex;
45
46 while (atomic_exchange_acquire (futex, 2) != 0)
47 {
48 futex:
49 LIBC_PROBE (lll_lock_wait, 1, futex);
50 futex_wait ((unsigned int *) futex, 2, private); /* Wait if *futex == 2. */
51 }
52}
53libc_hidden_def (__lll_lock_wait)
54
55void
56__lll_lock_wake_private (int *futex)
57{
58 lll_futex_wake (futex, 1, LLL_PRIVATE);
59}
60libc_hidden_def (__lll_lock_wake_private)
61
62void
63__lll_lock_wake (int *futex, int private)
64{
65 lll_futex_wake (futex, 1, private);
66}
67libc_hidden_def (__lll_lock_wake)
68
69#if ENABLE_ELISION_SUPPORT
70int __pthread_force_elision;
71libc_hidden_data_def (__pthread_force_elision)
72#endif
73