Linux kernel mirror (for testing)
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linux
1#ifndef __LINUX_SPINLOCK_UP_H
2#define __LINUX_SPINLOCK_UP_H
3
4#ifndef __LINUX_SPINLOCK_H
5# error "please don't include this file directly"
6#endif
7
8#include <asm/processor.h> /* for cpu_relax() */
9#include <asm/barrier.h>
10
11/*
12 * include/linux/spinlock_up.h - UP-debug version of spinlocks.
13 *
14 * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
15 * Released under the General Public License (GPL).
16 *
17 * In the debug case, 1 means unlocked, 0 means locked. (the values
18 * are inverted, to catch initialization bugs)
19 *
20 * No atomicity anywhere, we are on UP. However, we still need
21 * the compiler barriers, because we do not want the compiler to
22 * move potentially faulting instructions (notably user accesses)
23 * into the locked sequence, resulting in non-atomic execution.
24 */
25
26#ifdef CONFIG_DEBUG_SPINLOCK
27#define arch_spin_is_locked(x) ((x)->slock == 0)
28
29static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
30{
31 smp_cond_load_acquire(&lock->slock, VAL);
32}
33
34static inline void arch_spin_lock(arch_spinlock_t *lock)
35{
36 lock->slock = 0;
37 barrier();
38}
39
40static inline void
41arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
42{
43 local_irq_save(flags);
44 lock->slock = 0;
45 barrier();
46}
47
48static inline int arch_spin_trylock(arch_spinlock_t *lock)
49{
50 char oldval = lock->slock;
51
52 lock->slock = 0;
53 barrier();
54
55 return oldval > 0;
56}
57
58static inline void arch_spin_unlock(arch_spinlock_t *lock)
59{
60 barrier();
61 lock->slock = 1;
62}
63
64/*
65 * Read-write spinlocks. No debug version.
66 */
67#define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0)
68#define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0)
69#define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
70#define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; })
71#define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0)
72#define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
73
74#else /* DEBUG_SPINLOCK */
75#define arch_spin_is_locked(lock) ((void)(lock), 0)
76#define arch_spin_unlock_wait(lock) do { barrier(); (void)(lock); } while (0)
77/* for sched/core.c and kernel_lock.c: */
78# define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0)
79# define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0)
80# define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
81# define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; })
82#endif /* DEBUG_SPINLOCK */
83
84#define arch_spin_is_contended(lock) (((void)(lock), 0))
85
86#define arch_read_can_lock(lock) (((void)(lock), 1))
87#define arch_write_can_lock(lock) (((void)(lock), 1))
88
89#endif /* __LINUX_SPINLOCK_UP_H */