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Linux kernel mirror (for testing)
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kernel
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linux
1#ifndef __ASM_ARCH_SPINLOCK_H
2#define __ASM_ARCH_SPINLOCK_H
3
4#include <asm/system.h>
5
6#define RW_LOCK_BIAS 0x01000000
7#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 }
8#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
9
10#define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0)
11#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
12
13extern void cris_spin_unlock(void *l, int val);
14extern void cris_spin_lock(void *l);
15extern int cris_spin_trylock(void* l);
16
17static inline void _raw_spin_unlock(spinlock_t *lock)
18{
19 __asm__ volatile ("move.d %1,%0" \
20 : "=m" (lock->lock) \
21 : "r" (1) \
22 : "memory");
23}
24
25static inline int _raw_spin_trylock(spinlock_t *lock)
26{
27 return cris_spin_trylock((void*)&lock->lock);
28}
29
30static inline void _raw_spin_lock(spinlock_t *lock)
31{
32 cris_spin_lock((void*)&lock->lock);
33}
34
35static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
36{
37 _raw_spin_lock(lock);
38}
39
40/*
41 * Read-write spinlocks, allowing multiple readers
42 * but only one writer.
43 *
44 * NOTE! it is quite common to have readers in interrupts
45 * but no interrupt writers. For those circumstances we
46 * can "mix" irq-safe locks - any writer needs to get a
47 * irq-safe write-lock, but readers can get non-irqsafe
48 * read-locks.
49 */
50typedef struct {
51 spinlock_t lock;
52 volatile int counter;
53#ifdef CONFIG_PREEMPT
54 unsigned int break_lock;
55#endif
56} rwlock_t;
57
58#define RW_LOCK_UNLOCKED (rwlock_t) { {1}, 0 }
59
60#define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while (0)
61
62/**
63 * read_can_lock - would read_trylock() succeed?
64 * @lock: the rwlock in question.
65 */
66#define read_can_lock(x) ((int)(x)->counter >= 0)
67
68/**
69 * write_can_lock - would write_trylock() succeed?
70 * @lock: the rwlock in question.
71 */
72#define write_can_lock(x) ((x)->counter == 0)
73
74#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
75
76/* read_lock, read_unlock are pretty straightforward. Of course it somehow
77 * sucks we end up saving/restoring flags twice for read_lock_irqsave aso. */
78
79static __inline__ void _raw_read_lock(rwlock_t *rw)
80{
81 unsigned long flags;
82 local_irq_save(flags);
83 _raw_spin_lock(&rw->lock);
84
85 rw->counter++;
86
87 _raw_spin_unlock(&rw->lock);
88 local_irq_restore(flags);
89}
90
91static __inline__ void _raw_read_unlock(rwlock_t *rw)
92{
93 unsigned long flags;
94 local_irq_save(flags);
95 _raw_spin_lock(&rw->lock);
96
97 rw->counter--;
98
99 _raw_spin_unlock(&rw->lock);
100 local_irq_restore(flags);
101}
102
103/* write_lock is less trivial. We optimistically grab the lock and check
104 * if we surprised any readers. If so we release the lock and wait till
105 * they're all gone before trying again
106 *
107 * Also note that we don't use the _irqsave / _irqrestore suffixes here.
108 * If we're called with interrupts enabled and we've got readers (or other
109 * writers) in interrupt handlers someone fucked up and we'd dead-lock
110 * sooner or later anyway. prumpf */
111
112static __inline__ void _raw_write_lock(rwlock_t *rw)
113{
114retry:
115 _raw_spin_lock(&rw->lock);
116
117 if(rw->counter != 0) {
118 /* this basically never happens */
119 _raw_spin_unlock(&rw->lock);
120
121 while(rw->counter != 0);
122
123 goto retry;
124 }
125
126 /* got it. now leave without unlocking */
127 rw->counter = -1; /* remember we are locked */
128}
129
130/* write_unlock is absolutely trivial - we don't have to wait for anything */
131
132static __inline__ void _raw_write_unlock(rwlock_t *rw)
133{
134 rw->counter = 0;
135 _raw_spin_unlock(&rw->lock);
136}
137
138static __inline__ int _raw_write_trylock(rwlock_t *rw)
139{
140 _raw_spin_lock(&rw->lock);
141 if (rw->counter != 0) {
142 /* this basically never happens */
143 _raw_spin_unlock(&rw->lock);
144
145 return 0;
146 }
147
148 /* got it. now leave without unlocking */
149 rw->counter = -1; /* remember we are locked */
150 return 1;
151}
152
153static __inline__ int is_read_locked(rwlock_t *rw)
154{
155 return rw->counter > 0;
156}
157
158static __inline__ int is_write_locked(rwlock_t *rw)
159{
160 return rw->counter < 0;
161}
162
163#define _raw_spin_relax(lock) cpu_relax()
164#define _raw_read_relax(lock) cpu_relax()
165#define _raw_write_relax(lock) cpu_relax()
166
167#endif /* __ASM_ARCH_SPINLOCK_H */