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Linux kernel mirror (for testing)
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linux
1/*
2 * include/asm-s390/spinlock.h
3 *
4 * S390 version
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
7 *
8 * Derived from "include/asm-i386/spinlock.h"
9 */
10
11#ifndef __ASM_SPINLOCK_H
12#define __ASM_SPINLOCK_H
13
14#include <linux/smp.h>
15
16#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
17
18static inline int
19_raw_compare_and_swap(volatile unsigned int *lock,
20 unsigned int old, unsigned int new)
21{
22 asm volatile(
23 " cs %0,%3,%1"
24 : "=d" (old), "=Q" (*lock)
25 : "0" (old), "d" (new), "Q" (*lock)
26 : "cc", "memory" );
27 return old;
28}
29
30#else /* __GNUC__ */
31
32static inline int
33_raw_compare_and_swap(volatile unsigned int *lock,
34 unsigned int old, unsigned int new)
35{
36 asm volatile(
37 " cs %0,%3,0(%4)"
38 : "=d" (old), "=m" (*lock)
39 : "0" (old), "d" (new), "a" (lock), "m" (*lock)
40 : "cc", "memory" );
41 return old;
42}
43
44#endif /* __GNUC__ */
45
46/*
47 * Simple spin lock operations. There are two variants, one clears IRQ's
48 * on the local processor, one does not.
49 *
50 * We make no fairness assumptions. They have a cost.
51 *
52 * (the type definitions are in asm/spinlock_types.h)
53 */
54
55#define __raw_spin_is_locked(x) ((x)->owner_cpu != 0)
56#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
57#define __raw_spin_unlock_wait(lock) \
58 do { while (__raw_spin_is_locked(lock)) \
59 _raw_spin_relax(lock); } while (0)
60
61extern void _raw_spin_lock_wait(raw_spinlock_t *, unsigned int pc);
62extern int _raw_spin_trylock_retry(raw_spinlock_t *, unsigned int pc);
63extern void _raw_spin_relax(raw_spinlock_t *lock);
64
65static inline void __raw_spin_lock(raw_spinlock_t *lp)
66{
67 unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
68 int old;
69
70 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
71 if (likely(old == 0)) {
72 lp->owner_pc = pc;
73 return;
74 }
75 _raw_spin_lock_wait(lp, pc);
76}
77
78static inline int __raw_spin_trylock(raw_spinlock_t *lp)
79{
80 unsigned long pc = 1 | (unsigned long) __builtin_return_address(0);
81 int old;
82
83 old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id());
84 if (likely(old == 0)) {
85 lp->owner_pc = pc;
86 return 1;
87 }
88 return _raw_spin_trylock_retry(lp, pc);
89}
90
91static inline void __raw_spin_unlock(raw_spinlock_t *lp)
92{
93 lp->owner_pc = 0;
94 _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0);
95}
96
97/*
98 * Read-write spinlocks, allowing multiple readers
99 * but only one writer.
100 *
101 * NOTE! it is quite common to have readers in interrupts
102 * but no interrupt writers. For those circumstances we
103 * can "mix" irq-safe locks - any writer needs to get a
104 * irq-safe write-lock, but readers can get non-irqsafe
105 * read-locks.
106 */
107
108/**
109 * read_can_lock - would read_trylock() succeed?
110 * @lock: the rwlock in question.
111 */
112#define __raw_read_can_lock(x) ((int)(x)->lock >= 0)
113
114/**
115 * write_can_lock - would write_trylock() succeed?
116 * @lock: the rwlock in question.
117 */
118#define __raw_write_can_lock(x) ((x)->lock == 0)
119
120extern void _raw_read_lock_wait(raw_rwlock_t *lp);
121extern int _raw_read_trylock_retry(raw_rwlock_t *lp);
122extern void _raw_write_lock_wait(raw_rwlock_t *lp);
123extern int _raw_write_trylock_retry(raw_rwlock_t *lp);
124
125static inline void __raw_read_lock(raw_rwlock_t *rw)
126{
127 unsigned int old;
128 old = rw->lock & 0x7fffffffU;
129 if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
130 _raw_read_lock_wait(rw);
131}
132
133static inline void __raw_read_unlock(raw_rwlock_t *rw)
134{
135 unsigned int old, cmp;
136
137 old = rw->lock;
138 do {
139 cmp = old;
140 old = _raw_compare_and_swap(&rw->lock, old, old - 1);
141 } while (cmp != old);
142}
143
144static inline void __raw_write_lock(raw_rwlock_t *rw)
145{
146 if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
147 _raw_write_lock_wait(rw);
148}
149
150static inline void __raw_write_unlock(raw_rwlock_t *rw)
151{
152 _raw_compare_and_swap(&rw->lock, 0x80000000, 0);
153}
154
155static inline int __raw_read_trylock(raw_rwlock_t *rw)
156{
157 unsigned int old;
158 old = rw->lock & 0x7fffffffU;
159 if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
160 return 1;
161 return _raw_read_trylock_retry(rw);
162}
163
164static inline int __raw_write_trylock(raw_rwlock_t *rw)
165{
166 if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
167 return 1;
168 return _raw_write_trylock_retry(rw);
169}
170
171#define _raw_read_relax(lock) cpu_relax()
172#define _raw_write_relax(lock) cpu_relax()
173
174#endif /* __ASM_SPINLOCK_H */