summaryrefslogtreecommitdiff
path: root/arch/s390/include/asm/spinlock.h
blob: 0a29588aa00b64e21ffba5b31d77be94982f47a0 (plain)
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
/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  S390 version
 *    Copyright IBM Corp. 1999
 *    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>
#include <asm/atomic_ops.h>
#include <asm/barrier.h>
#include <asm/processor.h>
#include <asm/alternative.h>

#define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)

extern int spin_retry;

#ifndef CONFIG_SMP
static inline bool arch_vcpu_is_preempted(int cpu) { return false; }
#else
bool arch_vcpu_is_preempted(int cpu);
#endif

#define vcpu_is_preempted arch_vcpu_is_preempted

/*
 * 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)
 */

void arch_spin_relax(arch_spinlock_t *lock);
#define arch_spin_relax	arch_spin_relax

void arch_spin_lock_wait(arch_spinlock_t *);
int arch_spin_trylock_retry(arch_spinlock_t *);
void arch_spin_lock_setup(int cpu);

static inline u32 arch_spin_lockval(int cpu)
{
	return cpu + 1;
}

static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
	return lock.lock == 0;
}

static inline int arch_spin_is_locked(arch_spinlock_t *lp)
{
	return READ_ONCE(lp->lock) != 0;
}

static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
{
	barrier();
	return likely(__atomic_cmpxchg_bool(&lp->lock, 0, SPINLOCK_LOCKVAL));
}

static inline void arch_spin_lock(arch_spinlock_t *lp)
{
	if (!arch_spin_trylock_once(lp))
		arch_spin_lock_wait(lp);
}

static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
					unsigned long flags)
{
	if (!arch_spin_trylock_once(lp))
		arch_spin_lock_wait(lp);
}
#define arch_spin_lock_flags	arch_spin_lock_flags

static inline int arch_spin_trylock(arch_spinlock_t *lp)
{
	if (!arch_spin_trylock_once(lp))
		return arch_spin_trylock_retry(lp);
	return 1;
}

static inline void arch_spin_unlock(arch_spinlock_t *lp)
{
	typecheck(int, lp->lock);
	asm volatile(
		ALTERNATIVE("", ".long 0xb2fa0070", 49)	/* NIAI 7 */
		"	sth	%1,%0\n"
		: "=Q" (((unsigned short *) &lp->lock)[1])
		: "d" (0) : "cc", "memory");
}

/*
 * 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.
 */

#define arch_read_relax(rw) barrier()
#define arch_write_relax(rw) barrier()

void arch_read_lock_wait(arch_rwlock_t *lp);
void arch_write_lock_wait(arch_rwlock_t *lp);

static inline void arch_read_lock(arch_rwlock_t *rw)
{
	int old;

	old = __atomic_add(1, &rw->cnts);
	if (old & 0xffff0000)
		arch_read_lock_wait(rw);
}

static inline void arch_read_unlock(arch_rwlock_t *rw)
{
	__atomic_add_const_barrier(-1, &rw->cnts);
}

static inline void arch_write_lock(arch_rwlock_t *rw)
{
	if (!__atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000))
		arch_write_lock_wait(rw);
}

static inline void arch_write_unlock(arch_rwlock_t *rw)
{
	__atomic_add_barrier(-0x30000, &rw->cnts);
}


static inline int arch_read_trylock(arch_rwlock_t *rw)
{
	int old;

	old = READ_ONCE(rw->cnts);
	return (!(old & 0xffff0000) &&
		__atomic_cmpxchg_bool(&rw->cnts, old, old + 1));
}

static inline int arch_write_trylock(arch_rwlock_t *rw)
{
	int old;

	old = READ_ONCE(rw->cnts);
	return !old && __atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000);
}

#endif /* __ASM_SPINLOCK_H */