aboutsummaryrefslogtreecommitdiff
path: root/arch/s390/lib/spinlock.c
blob: 284d879a9b8c03a6c88d3d84a0b72abce53e8b2c (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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
/*
 *    Out of line spinlock code.
 *
 *    Copyright IBM Corp. 2004, 2006
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <asm/io.h>

int spin_retry = 1000;

/**
 * spin_retry= parameter
 */
static int __init spin_retry_setup(char *str)
{
	spin_retry = simple_strtoul(str, &str, 0);
	return 1;
}
__setup("spin_retry=", spin_retry_setup);

void arch_spin_lock_wait(arch_spinlock_t *lp)
{
	unsigned int cpu = SPINLOCK_LOCKVAL;
	unsigned int owner;
	int count;

	while (1) {
		owner = lp->lock;
		if (!owner || smp_vcpu_scheduled(~owner)) {
			count = spin_retry;
			do {
				if (arch_spin_is_locked(lp))
					continue;
				if (_raw_compare_and_swap(&lp->lock, 0, cpu))
					return;
			} while (count-- > 0);
			if (MACHINE_IS_LPAR)
				continue;
		}
		owner = lp->lock;
		if (owner)
			smp_yield_cpu(~owner);
		if (_raw_compare_and_swap(&lp->lock, 0, cpu))
			return;
	}
}
EXPORT_SYMBOL(arch_spin_lock_wait);

void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
	unsigned int cpu = SPINLOCK_LOCKVAL;
	unsigned int owner;
	int count;

	local_irq_restore(flags);
	while (1) {
		owner = lp->lock;
		if (!owner || smp_vcpu_scheduled(~owner)) {
			count = spin_retry;
			do {
				if (arch_spin_is_locked(lp))
					continue;
				local_irq_disable();
				if (_raw_compare_and_swap(&lp->lock, 0, cpu))
					return;
				local_irq_restore(flags);
			} while (count-- > 0);
			if (MACHINE_IS_LPAR)
				continue;
		}
		owner = lp->lock;
		if (owner)
			smp_yield_cpu(~owner);
		local_irq_disable();
		if (_raw_compare_and_swap(&lp->lock, 0, cpu))
			return;
		local_irq_restore(flags);
	}
}
EXPORT_SYMBOL(arch_spin_lock_wait_flags);

void arch_spin_relax(arch_spinlock_t *lp)
{
	unsigned int cpu = lp->lock;
	if (cpu != 0) {
		if (MACHINE_IS_VM || MACHINE_IS_KVM ||
		    !smp_vcpu_scheduled(~cpu))
			smp_yield_cpu(~cpu);
	}
}
EXPORT_SYMBOL(arch_spin_relax);

int arch_spin_trylock_retry(arch_spinlock_t *lp)
{
	int count;

	for (count = spin_retry; count > 0; count--)
		if (arch_spin_trylock_once(lp))
			return 1;
	return 0;
}
EXPORT_SYMBOL(arch_spin_trylock_retry);

void _raw_read_lock_wait(arch_rwlock_t *rw)
{
	unsigned int old;
	int count = spin_retry;

	while (1) {
		if (count-- <= 0) {
			smp_yield();
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		if ((int) old < 0)
			continue;
		if (_raw_compare_and_swap(&rw->lock, old, old + 1))
			return;
	}
}
EXPORT_SYMBOL(_raw_read_lock_wait);

void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
{
	unsigned int old;
	int count = spin_retry;

	local_irq_restore(flags);
	while (1) {
		if (count-- <= 0) {
			smp_yield();
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		if ((int) old < 0)
			continue;
		local_irq_disable();
		if (_raw_compare_and_swap(&rw->lock, old, old + 1))
			return;
	}
}
EXPORT_SYMBOL(_raw_read_lock_wait_flags);

int _raw_read_trylock_retry(arch_rwlock_t *rw)
{
	unsigned int old;
	int count = spin_retry;

	while (count-- > 0) {
		old = ACCESS_ONCE(rw->lock);
		if ((int) old < 0)
			continue;
		if (_raw_compare_and_swap(&rw->lock, old, old + 1))
			return 1;
	}
	return 0;
}
EXPORT_SYMBOL(_raw_read_trylock_retry);

void _raw_write_lock_wait(arch_rwlock_t *rw)
{
	unsigned int old;
	int count = spin_retry;

	while (1) {
		if (count-- <= 0) {
			smp_yield();
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		if (old)
			continue;
		if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
			return;
	}
}
EXPORT_SYMBOL(_raw_write_lock_wait);

void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
{
	unsigned int old;
	int count = spin_retry;

	local_irq_restore(flags);
	while (1) {
		if (count-- <= 0) {
			smp_yield();
			count = spin_retry;
		}
		old = ACCESS_ONCE(rw->lock);
		if (old)
			continue;
		local_irq_disable();
		if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
			return;
	}
}
EXPORT_SYMBOL(_raw_write_lock_wait_flags);

int _raw_write_trylock_retry(arch_rwlock_t *rw)
{
	unsigned int old;
	int count = spin_retry;

	while (count-- > 0) {
		old = ACCESS_ONCE(rw->lock);
		if (old)
			continue;
		if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000))
			return 1;
	}
	return 0;
}
EXPORT_SYMBOL(_raw_write_trylock_retry);