1 /* POSIX spinlock implementation. Arm version.
2 Copyright (C) 2000 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 License as
7 published by the Free Software Foundation; either version 2.1 of the
8 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; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
19
20 #include <errno.h>
21 #include <pthread.h>
22 #include "internals.h"
23
24
25 int
__pthread_spin_lock(pthread_spinlock_t * lock)26 __pthread_spin_lock (pthread_spinlock_t *lock)
27 {
28 unsigned int val;
29
30 do
31 val = __atomic_exchange_n(lock, 1, __ATOMIC_ACQUIRE);
32 while (val != 0);
33
34 return 0;
35 }
weak_alias(__pthread_spin_lock,pthread_spin_lock)36 weak_alias (__pthread_spin_lock, pthread_spin_lock)
37
38
39 int
40 __pthread_spin_trylock (pthread_spinlock_t *lock)
41 {
42 unsigned int val;
43 val = __atomic_exchange_n(lock, 1, __ATOMIC_ACQUIRE);
44 return val ? EBUSY : 0;
45 }
weak_alias(__pthread_spin_trylock,pthread_spin_trylock)46 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
47
48
49 int
50 __pthread_spin_unlock (pthread_spinlock_t *lock)
51 {
52 __atomic_store_n(lock, 0, __ATOMIC_RELEASE);
53 return 0;
54 }
weak_alias(__pthread_spin_unlock,pthread_spin_unlock)55 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
56
57
58 int
59 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
60 {
61 /* We can ignore the `pshared' parameter. Since we are busy-waiting
62 all processes which can access the memory location `lock' points
63 to can use the spinlock. */
64 return *lock = 0;
65 }
weak_alias(__pthread_spin_init,pthread_spin_init)66 weak_alias (__pthread_spin_init, pthread_spin_init)
67
68
69 int
70 __pthread_spin_destroy (pthread_spinlock_t *lock)
71 {
72 /* Nothing to do. */
73 return 0;
74 }
75 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)
76