1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/*
* include/asm-s390/spinlock.h
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Derived from "include/asm-i386/spinlock.h"
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <linux/smp.h>
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
static inline int
_raw_compare_and_swap(volatile unsigned int *lock,
unsigned int old, unsigned int new)
{
asm volatile(
" cs %0,%3,%1"
: "=d" (old), "=Q" (*lock)
: "0" (old), "d" (new), "Q" (*lock)
: "cc", "memory" );
return old;
}
#else /* __GNUC__ */
static inline int
_raw_compare_and_swap(volatile unsigned int *lock,
unsigned int old, unsigned int new)
{
asm volatile(
" cs %0,%3,0(%4)"
: "=d" (old), "=m" (*lock)
: "0" (old), "d" (new), "a" (lock), "m" (*lock)
: "cc", "memory" );
return old;
}
#endif /* __GNUC__ */
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* We make no fairness assumptions. They have a cost.
*
* (the type definitions are in asm/spinlock_types.h)
*/
#define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
#define __raw_spin_unlock_wait(lock) \
do { while (__raw_spin_is_locked(lock)) \
_raw_spin_relax(lock); } while (0)
extern void _raw_spin_lock_wait(raw_spinlock_t *);
extern int _raw_spin_trylock_retry(raw_spinlock_t *);
extern void _raw_spin_relax(raw_spinlock_t *lock);
static inline void __raw_spin_lock(raw_spinlock_t *lp)
{
int old;
old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
if (likely(old == 0))
return;
_raw_spin_lock_wait(lp);
}
static inline int __raw_spin_trylock(raw_spinlock_t *lp)
{
int old;
old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
if (likely(old == 0))
return 1;
return _raw_spin_trylock_retry(lp);
}
static inline void __raw_spin_unlock(raw_spinlock_t *lp)
{
_raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
}
/*
* Read-write spinlocks, allowing multiple readers
* but only one writer.
*
* NOTE! it is quite common to have readers in interrupts
* but no interrupt writers. For those circumstances we
* can "mix" irq-safe locks - any writer needs to get a
* irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*/
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define __raw_write_can_lock(x) ((x)->lock == 0)
extern void _raw_read_lock_wait(raw_rwlock_t *lp);
extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
extern void _raw_write_lock_wait(raw_rwlock_t *lp);
extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
unsigned int old;
old = rw->lock & 0x7fffffffU;
if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
_raw_read_lock_wait(rw);
}
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
unsigned int old, cmp;
old = rw->lock;
do {
cmp = old;
old = _raw_compare_and_swap(&rw->lock, old, old - 1);
} while (cmp != old);
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
_raw_write_lock_wait(rw);
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
_raw_compare_and_swap(&rw->lock, 0x80000000, 0);
}
static inline int __raw_read_trylock(raw_rwlock_t *rw)
{
unsigned int old;
old = rw->lock & 0x7fffffffU;
if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
return 1;
return _raw_read_trylock_retry(rw);
}
static inline int __raw_write_trylock(raw_rwlock_t *rw)
{
if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
return 1;
return _raw_write_trylock_retry(rw);
}
#define _raw_read_relax(lock) cpu_relax()
#define _raw_write_relax(lock) cpu_relax()
#endif /* __ASM_SPINLOCK_H */
|
