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