aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/spinlock.c
blob: b31e54eadf56585d8da288e076768bf9932f5711 (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
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
/*
 * Copyright (2004) Linus Torvalds
 *
 * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
 *
 * Copyright (2004, 2005) Ingo Molnar
 *
 * This file contains the spinlock/rwlock implementations for the
 * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
 */

#include <linux/linkage.h>
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>

/*
 * Generic declaration of the raw read_trylock() function,
 * architectures are supposed to optimize this:
 */
int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock)
{
	__raw_read_lock(lock);
	return 1;
}
EXPORT_SYMBOL(generic__raw_read_trylock);

int __lockfunc _spin_trylock(spinlock_t *lock)
{
	preempt_disable();
	if (_raw_spin_trylock(lock))
		return 1;
	
	preempt_enable();
	return 0;
}
EXPORT_SYMBOL(_spin_trylock);

int __lockfunc _read_trylock(rwlock_t *lock)
{
	preempt_disable();
	if (_raw_read_trylock(lock))
		return 1;

	preempt_enable();
	return 0;
}
EXPORT_SYMBOL(_read_trylock);

int __lockfunc _write_trylock(rwlock_t *lock)
{
	preempt_disable();
	if (_raw_write_trylock(lock))
		return 1;

	preempt_enable();
	return 0;
}
EXPORT_SYMBOL(_write_trylock);

#if !defined(CONFIG_PREEMPT) || !defined(CONFIG_SMP)

void __lockfunc _read_lock(rwlock_t *lock)
{
	preempt_disable();
	_raw_read_lock(lock);
}
EXPORT_SYMBOL(_read_lock);

unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
{
	unsigned long flags;

	local_irq_save(flags);
	preempt_disable();
	_raw_spin_lock_flags(lock, &flags);
	return flags;
}
EXPORT_SYMBOL(_spin_lock_irqsave);

void __lockfunc _spin_lock_irq(spinlock_t *lock)
{
	local_irq_disable();
	preempt_disable();
	_raw_spin_lock(lock);
}
EXPORT_SYMBOL(_spin_lock_irq);

void __lockfunc _spin_lock_bh(spinlock_t *lock)
{
	local_bh_disable();
	preempt_disable();
	_raw_spin_lock(lock);
}
EXPORT_SYMBOL(_spin_lock_bh);

unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
{
	unsigned long flags;

	local_irq_save(flags);
	preempt_disable();
	_raw_read_lock(lock);
	return flags;
}
EXPORT_SYMBOL(_read_lock_irqsave);

void __lockfunc _read_lock_irq(rwlock_t *lock)
{
	local_irq_disable();
	preempt_disable();
	_raw_read_lock(lock);
}
EXPORT_SYMBOL(_read_lock_irq);

void __lockfunc _read_lock_bh(rwlock_t *lock)
{
	local_bh_disable();
	preempt_disable();
	_raw_read_lock(lock);
}
EXPORT_SYMBOL(_read_lock_bh);

unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
{
	unsigned long flags;

	local_irq_save(flags);
	preempt_disable();
	_raw_write_lock(lock);
	return flags;
}
EXPORT_SYMBOL(_write_lock_irqsave);

void __lockfunc _write_lock_irq(rwlock_t *lock)
{
	local_irq_disable();
	preempt_disable();
	_raw_write_lock(lock);
}
EXPORT_SYMBOL(_write_lock_irq);

void __lockfunc _write_lock_bh(rwlock_t *lock)
{
	local_bh_disable();
	preempt_disable();
	_raw_write_lock(lock);
}
EXPORT_SYMBOL(_write_lock_bh);

void __lockfunc _spin_lock(spinlock_t *lock)
{
	preempt_disable();
	_raw_spin_lock(lock);
}

EXPORT_SYMBOL(_spin_lock);

void __lockfunc _write_lock(rwlock_t *lock)
{
	preempt_disable();
	_raw_write_lock(lock);
}

EXPORT_SYMBOL(_write_lock);

#else /* CONFIG_PREEMPT: */

/*
 * This could be a long-held lock. We both prepare to spin for a long
 * time (making _this_ CPU preemptable if possible), and we also signal
 * towards that other CPU that it should break the lock ASAP.
 *
 * (We do this in a function because inlining it would be excessive.)
 */

#define BUILD_LOCK_OPS(op, locktype)					\
void __lockfunc _##op##_lock(locktype##_t *lock)			\
{									\
	for (;;) {							\
		preempt_disable();					\
		if (likely(_raw_##op##_trylock(lock)))			\
			break;						\
		preempt_enable();					\
									\
		if (!(lock)->break_lock)				\
			(lock)->break_lock = 1;				\
		while (!op##_can_lock(lock) && (lock)->break_lock)	\
			cpu_relax();					\
	}								\
	(lock)->break_lock = 0;						\
}									\
									\
EXPORT_SYMBOL(_##op##_lock);						\
									\
unsigned long __lockfunc _##op##_lock_irqsave(locktype##_t *lock)	\
{									\
	unsigned long flags;						\
									\
	for (;;) {							\
		preempt_disable();					\
		local_irq_save(flags);					\
		if (likely(_raw_##op##_trylock(lock)))			\
			break;						\
		local_irq_restore(flags);				\
		preempt_enable();					\
									\
		if (!(lock)->break_lock)				\
			(lock)->break_lock = 1;				\
		while (!op##_can_lock(lock) && (lock)->break_lock)	\
			cpu_relax();					\
	}								\
	(lock)->break_lock = 0;						\
	return flags;							\
}									\
									\
EXPORT_SYMBOL(_##op##_lock_irqsave);					\
									\
void __lockfunc _##op##_lock_irq(locktype##_t *lock)			\
{									\
	_##op##_lock_irqsave(lock);					\
}									\
									\
EXPORT_SYMBOL(_##op##_lock_irq);					\
									\
void __lockfunc _##op##_lock_bh(locktype##_t *lock)			\
{									\
	unsigned long flags;						\
									\
	/*							*/	\
	/* Careful: we must exclude softirqs too, hence the	*/	\
	/* irq-disabling. We use the generic preemption-aware	*/	\
	/* function:						*/	\
	/**/								\
	flags = _##op##_lock_irqsave(lock);				\
	local_bh_disable();						\
	local_irq_restore(flags);					\
}									\
									\
EXPORT_SYMBOL(_##op##_lock_bh)

/*
 * Build preemption-friendly versions of the following
 * lock-spinning functions:
 *
 *         _[spin|read|write]_lock()
 *         _[spin|read|write]_lock_irq()
 *         _[spin|read|write]_lock_irqsave()
 *         _[spin|read|write]_lock_bh()
 */
BUILD_LOCK_OPS(spin, spinlock);
BUILD_LOCK_OPS(read, rwlock);
BUILD_LOCK_OPS(write, rwlock);

#endif /* CONFIG_PREEMPT */

void __lockfunc _spin_unlock(spinlock_t *lock)
{
	_raw_spin_unlock(lock);
	preempt_enable();
}
EXPORT_SYMBOL(_spin_unlock);

void __lockfunc _write_unlock(rwlock_t *lock)
{
	_raw_write_unlock(lock);
	preempt_enable();
}
EXPORT_SYMBOL(_write_unlock);

void __lockfunc _read_unlock(rwlock_t *lock)
{
	_raw_read_unlock(lock);
	preempt_enable();
}
EXPORT_SYMBOL(_read_unlock);

void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
{
	_raw_spin_unlock(lock);
	local_irq_restore(flags);
	preempt_enable();
}
EXPORT_SYMBOL(_spin_unlock_irqrestore);

void __lockfunc _spin_unlock_irq(spinlock_t *lock)
{
	_raw_spin_unlock(lock);
	local_irq_enable();
	preempt_enable();
}
EXPORT_SYMBOL(_spin_unlock_irq);

void __lockfunc _spin_unlock_bh(spinlock_t *lock)
{
	_raw_spin_unlock(lock);
	preempt_enable_no_resched();
	local_bh_enable();
}
EXPORT_SYMBOL(_spin_unlock_bh);

void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
	_raw_read_unlock(lock);
	local_irq_restore(flags);
	preempt_enable();
}
EXPORT_SYMBOL(_read_unlock_irqrestore);

void __lockfunc _read_unlock_irq(rwlock_t *lock)
{
	_raw_read_unlock(lock);
	local_irq_enable();
	preempt_enable();
}
EXPORT_SYMBOL(_read_unlock_irq);

void __lockfunc _read_unlock_bh(rwlock_t *lock)
{
	_raw_read_unlock(lock);
	preempt_enable_no_resched();
	local_bh_enable();
}
EXPORT_SYMBOL(_read_unlock_bh);

void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
	_raw_write_unlock(lock);
	local_irq_restore(flags);
	preempt_enable();
}
EXPORT_SYMBOL(_write_unlock_irqrestore);

void __lockfunc _write_unlock_irq(rwlock_t *lock)
{
	_raw_write_unlock(lock);
	local_irq_enable();
	preempt_enable();
}
EXPORT_SYMBOL(_write_unlock_irq);

void __lockfunc _write_unlock_bh(rwlock_t *lock)
{
	_raw_write_unlock(lock);
	preempt_enable_no_resched();
	local_bh_enable();
}
EXPORT_SYMBOL(_write_unlock_bh);

int __lockfunc _spin_trylock_bh(spinlock_t *lock)
{
	local_bh_disable();
	preempt_disable();
	if (_raw_spin_trylock(lock))
		return 1;

	preempt_enable_no_resched();
	local_bh_enable();
	return 0;
}
EXPORT_SYMBOL(_spin_trylock_bh);

int in_lock_functions(unsigned long addr)
{
	/* Linker adds these: start and end of __lockfunc functions */
	extern char __lock_text_start[], __lock_text_end[];

	return addr >= (unsigned long)__lock_text_start
	&& addr < (unsigned long)__lock_text_end;
}
EXPORT_SYMBOL(in_lock_functions);