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}
38
39
40/* This function doesn't get included in libc. */
41#if IS_IN (libpthread)
42void
43__lll_lock_wait (int *futex, int private)
44{
45 if (atomic_load_relaxed (futex) == 2)
46 goto futex;
47
48 while (atomic_exchange_acquire (futex, 2) != 0)
49 {
50 futex:
51 LIBC_PROBE (lll_lock_wait, 1, futex);
52 futex_wait ((unsigned int *) futex, 2, private); /* Wait if *futex == 2. */
53 }
54}
55#endif
56