summaryrefslogtreecommitdiffstats
path: root/kernel/spinlock.c
blob: e6e13631843793a6e9facbbe8c783855096eb8cd (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
373
374
375
376
377
378
379
380
381
382
383
/*
 * 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)
 *
 * Note that some architectures have special knowledge about the
 * stack frames of these functions in their profile_pc. If you
 * change anything significant here that could change the stack
 * frame contact the architecture maintainers.
 */

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

/*
 * If lockdep is enabled then we use the non-preemption spin-ops
 * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
 * not re-enabled during lock-acquire (which the preempt-spin-ops do):
 */
#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
/*
 * The __lock_function inlines are taken from
 * include/linux/spinlock_api_smp.h
 */
#else
/*
 * We build the __lock_function inlines here. They are too large for
 * inlining all over the place, but here is only one user per function
 * which embedds them into the calling _lock_function below.
 *
 * 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.
 */
#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)	\
			_raw_##op##_relax(&lock->raw_lock);		\
	}								\
	(lock)->break_lock = 0;						\
}									\
									\
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)	\
			_raw_##op##_relax(&lock->raw_lock);		\
	}								\
	(lock)->break_lock = 0;						\
	return flags;							\
}									\
									\
void __lockfunc __##op##_lock_irq(locktype##_t *lock)			\
{									\
	_##op##_lock_irqsave(lock);					\
}									\
									\
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);					\
}									\

/*
 * 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

#ifndef CONFIG_INLINE_SPIN_TRYLOCK
int __lockfunc _spin_trylock(spinlock_t *lock)
{
	return __spin_trylock(lock);
}
EXPORT_SYMBOL(_spin_trylock);
#endif

#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
int __lockfunc _spin_trylock_bh(spinlock_t *lock)
{
	return __spin_trylock_bh(lock);
}
EXPORT_SYMBOL(_spin_trylock_bh);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK
void __lockfunc _spin_lock(spinlock_t *lock)
{
	__spin_lock(lock);
}
EXPORT_SYMBOL(_spin_lock);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
{
	return __spin_lock_irqsave(lock);
}
EXPORT_SYMBOL(_spin_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
void __lockfunc _spin_lock_irq(spinlock_t *lock)
{
	__spin_lock_irq(lock);
}
EXPORT_SYMBOL(_spin_lock_irq);
#endif

#ifndef CONFIG_INLINE_SPIN_LOCK_BH
void __lockfunc _spin_lock_bh(spinlock_t *lock)
{
	__spin_lock_bh(lock);
}
EXPORT_SYMBOL(_spin_lock_bh);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK
void __lockfunc _spin_unlock(spinlock_t *lock)
{
	__spin_unlock(lock);
}
EXPORT_SYMBOL(_spin_unlock);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
{
	__spin_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_spin_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
void __lockfunc _spin_unlock_irq(spinlock_t *lock)
{
	__spin_unlock_irq(lock);
}
EXPORT_SYMBOL(_spin_unlock_irq);
#endif

#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
void __lockfunc _spin_unlock_bh(spinlock_t *lock)
{
	__spin_unlock_bh(lock);
}
EXPORT_SYMBOL(_spin_unlock_bh);
#endif

#ifndef CONFIG_INLINE_READ_TRYLOCK
int __lockfunc _read_trylock(rwlock_t *lock)
{
	return __read_trylock(lock);
}
EXPORT_SYMBOL(_read_trylock);
#endif

#ifndef CONFIG_INLINE_READ_LOCK
void __lockfunc _read_lock(rwlock_t *lock)
{
	__read_lock(lock);
}
EXPORT_SYMBOL(_read_lock);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
{
	return __read_lock_irqsave(lock);
}
EXPORT_SYMBOL(_read_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_IRQ
void __lockfunc _read_lock_irq(rwlock_t *lock)
{
	__read_lock_irq(lock);
}
EXPORT_SYMBOL(_read_lock_irq);
#endif

#ifndef CONFIG_INLINE_READ_LOCK_BH
void __lockfunc _read_lock_bh(rwlock_t *lock)
{
	__read_lock_bh(lock);
}
EXPORT_SYMBOL(_read_lock_bh);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK
void __lockfunc _read_unlock(rwlock_t *lock)
{
	__read_unlock(lock);
}
EXPORT_SYMBOL(_read_unlock);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
	__read_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_read_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
void __lockfunc _read_unlock_irq(rwlock_t *lock)
{
	__read_unlock_irq(lock);
}
EXPORT_SYMBOL(_read_unlock_irq);
#endif

#ifndef CONFIG_INLINE_READ_UNLOCK_BH
void __lockfunc _read_unlock_bh(rwlock_t *lock)
{
	__read_unlock_bh(lock);
}
EXPORT_SYMBOL(_read_unlock_bh);
#endif

#ifndef CONFIG_INLINE_WRITE_TRYLOCK
int __lockfunc _write_trylock(rwlock_t *lock)
{
	return __write_trylock(lock);
}
EXPORT_SYMBOL(_write_trylock);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK
void __lockfunc _write_lock(rwlock_t *lock)
{
	__write_lock(lock);
}
EXPORT_SYMBOL(_write_lock);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
{
	return __write_lock_irqsave(lock);
}
EXPORT_SYMBOL(_write_lock_irqsave);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
void __lockfunc _write_lock_irq(rwlock_t *lock)
{
	__write_lock_irq(lock);
}
EXPORT_SYMBOL(_write_lock_irq);
#endif

#ifndef CONFIG_INLINE_WRITE_LOCK_BH
void __lockfunc _write_lock_bh(rwlock_t *lock)
{
	__write_lock_bh(lock);
}
EXPORT_SYMBOL(_write_lock_bh);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK
void __lockfunc _write_unlock(rwlock_t *lock)
{
	__write_unlock(lock);
}
EXPORT_SYMBOL(_write_unlock);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
{
	__write_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(_write_unlock_irqrestore);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
void __lockfunc _write_unlock_irq(rwlock_t *lock)
{
	__write_unlock_irq(lock);
}
EXPORT_SYMBOL(_write_unlock_irq);
#endif

#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
void __lockfunc _write_unlock_bh(rwlock_t *lock)
{
	__write_unlock_bh(lock);
}
EXPORT_SYMBOL(_write_unlock_bh);
#endif

#ifdef CONFIG_DEBUG_LOCK_ALLOC

void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
{
	preempt_disable();
	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
	LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
}
EXPORT_SYMBOL(_spin_lock_nested);

unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock,
						   int subclass)
{
	unsigned long flags;

	local_irq_save(flags);
	preempt_disable();
	spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
	LOCK_CONTENDED_FLAGS(lock, _raw_spin_trylock, _raw_spin_lock,
				_raw_spin_lock_flags, &flags);
	return flags;
}
EXPORT_SYMBOL(_spin_lock_irqsave_nested);

void __lockfunc _spin_lock_nest_lock(spinlock_t *lock,
				     struct lockdep_map *nest_lock)
{
	preempt_disable();
	spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
	LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
}
EXPORT_SYMBOL(_spin_lock_nest_lock);

#endif

notrace 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);