aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/spinlock.h
blob: d6ba068719b61bf4a035e4d6e297694b65941442 (plain) (blame)
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
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
#ifndef __LINUX_SPINLOCK_H
#define __LINUX_SPINLOCK_H

/*
 * include/linux/spinlock.h - generic locking declarations
 */

#include <linux/config.h>
#include <linux/preempt.h>
#include <linux/linkage.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <linux/kernel.h>
#include <linux/stringify.h>

#include <asm/processor.h>	/* for cpu relax */
#include <asm/system.h>

/*
 * Must define these before including other files, inline functions need them
 */
#define LOCK_SECTION_NAME                       \
        ".text.lock." __stringify(KBUILD_BASENAME)

#define LOCK_SECTION_START(extra)               \
        ".subsection 1\n\t"                     \
        extra                                   \
        ".ifndef " LOCK_SECTION_NAME "\n\t"     \
        LOCK_SECTION_NAME ":\n\t"               \
        ".endif\n"

#define LOCK_SECTION_END                        \
        ".previous\n\t"

#define __lockfunc fastcall __attribute__((section(".spinlock.text")))

/*
 * If CONFIG_SMP is set, pull in the _raw_* definitions
 */
#ifdef CONFIG_SMP

#define assert_spin_locked(x)	BUG_ON(!spin_is_locked(x))
#include <asm/spinlock.h>

int __lockfunc _spin_trylock(spinlock_t *lock);
int __lockfunc _read_trylock(rwlock_t *lock);
int __lockfunc _write_trylock(rwlock_t *lock);

void __lockfunc _spin_lock(spinlock_t *lock)	__acquires(spinlock_t);
void __lockfunc _read_lock(rwlock_t *lock)	__acquires(rwlock_t);
void __lockfunc _write_lock(rwlock_t *lock)	__acquires(rwlock_t);

void __lockfunc _spin_unlock(spinlock_t *lock)	__releases(spinlock_t);
void __lockfunc _read_unlock(rwlock_t *lock)	__releases(rwlock_t);
void __lockfunc _write_unlock(rwlock_t *lock)	__releases(rwlock_t);

unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)	__acquires(spinlock_t);
unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)	__acquires(rwlock_t);
unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)	__acquires(rwlock_t);

void __lockfunc _spin_lock_irq(spinlock_t *lock)	__acquires(spinlock_t);
void __lockfunc _spin_lock_bh(spinlock_t *lock)		__acquires(spinlock_t);
void __lockfunc _read_lock_irq(rwlock_t *lock)		__acquires(rwlock_t);
void __lockfunc _read_lock_bh(rwlock_t *lock)		__acquires(rwlock_t);
void __lockfunc _write_lock_irq(rwlock_t *lock)		__acquires(rwlock_t);
void __lockfunc _write_lock_bh(rwlock_t *lock)		__acquires(rwlock_t);

void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)	__releases(spinlock_t);
void __lockfunc _spin_unlock_irq(spinlock_t *lock)				__releases(spinlock_t);
void __lockfunc _spin_unlock_bh(spinlock_t *lock)				__releases(spinlock_t);
void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)	__releases(rwlock_t);
void __lockfunc _read_unlock_irq(rwlock_t *lock)				__releases(rwlock_t);
void __lockfunc _read_unlock_bh(rwlock_t *lock)					__releases(rwlock_t);
void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)	__releases(rwlock_t);
void __lockfunc _write_unlock_irq(rwlock_t *lock)				__releases(rwlock_t);
void __lockfunc _write_unlock_bh(rwlock_t *lock)				__releases(rwlock_t);

int __lockfunc _spin_trylock_bh(spinlock_t *lock);
int __lockfunc generic_raw_read_trylock(rwlock_t *lock);
int in_lock_functions(unsigned long addr);

#else

#define in_lock_functions(ADDR) 0

#if !defined(CONFIG_PREEMPT) && !defined(CONFIG_DEBUG_SPINLOCK)
# define _atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
# define ATOMIC_DEC_AND_LOCK
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 
#define SPINLOCK_MAGIC	0x1D244B3C
typedef struct {
	unsigned long magic;
	volatile unsigned long lock;
	volatile unsigned int babble;
	const char *module;
	char *owner;
	int oline;
} spinlock_t;
#define SPIN_LOCK_UNLOCKED (spinlock_t) { SPINLOCK_MAGIC, 0, 10, __FILE__ , NULL, 0}

#define spin_lock_init(x) \
	do { \
		(x)->magic = SPINLOCK_MAGIC; \
		(x)->lock = 0; \
		(x)->babble = 5; \
		(x)->module = __FILE__; \
		(x)->owner = NULL; \
		(x)->oline = 0; \
	} while (0)

#define CHECK_LOCK(x) \
	do { \
	 	if ((x)->magic != SPINLOCK_MAGIC) { \
			printk(KERN_ERR "%s:%d: spin_is_locked on uninitialized spinlock %p.\n", \
					__FILE__, __LINE__, (x)); \
		} \
	} while(0)

#define _raw_spin_lock(x)		\
	do { \
	 	CHECK_LOCK(x); \
		if ((x)->lock&&(x)->babble) { \
			(x)->babble--; \
			printk("%s:%d: spin_lock(%s:%p) already locked by %s/%d\n", \
					__FILE__,__LINE__, (x)->module, \
					(x), (x)->owner, (x)->oline); \
		} \
		(x)->lock = 1; \
		(x)->owner = __FILE__; \
		(x)->oline = __LINE__; \
	} while (0)

/* without debugging, spin_is_locked on UP always says
 * FALSE. --> printk if already locked. */
#define spin_is_locked(x) \
	({ \
	 	CHECK_LOCK(x); \
		if ((x)->lock&&(x)->babble) { \
			(x)->babble--; \
			printk("%s:%d: spin_is_locked(%s:%p) already locked by %s/%d\n", \
					__FILE__,__LINE__, (x)->module, \
					(x), (x)->owner, (x)->oline); \
		} \
		0; \
	})

/* with debugging, assert_spin_locked() on UP does check
 * the lock value properly */
#define assert_spin_locked(x) \
	({ \
		CHECK_LOCK(x); \
		BUG_ON(!(x)->lock); \
	})

/* without debugging, spin_trylock on UP always says
 * TRUE. --> printk if already locked. */
#define _raw_spin_trylock(x) \
	({ \
	 	CHECK_LOCK(x); \
		if ((x)->lock&&(x)->babble) { \
			(x)->babble--; \
			printk("%s:%d: spin_trylock(%s:%p) already locked by %s/%d\n", \
					__FILE__,__LINE__, (x)->module, \
					(x), (x)->owner, (x)->oline); \
		} \
		(x)->lock = 1; \
		(x)->owner = __FILE__; \
		(x)->oline = __LINE__; \
		1; \
	})

#define spin_unlock_wait(x)	\
	do { \
	 	CHECK_LOCK(x); \
		if ((x)->lock&&(x)->babble) { \
			(x)->babble--; \
			printk("%s:%d: spin_unlock_wait(%s:%p) owned by %s/%d\n", \
					__FILE__,__LINE__, (x)->module, (x), \
					(x)->owner, (x)->oline); \
		}\
	} while (0)

#define _raw_spin_unlock(x) \
	do { \
	 	CHECK_LOCK(x); \
		if (!(x)->lock&&(x)->babble) { \
			(x)->babble--; \
			printk("%s:%d: spin_unlock(%s:%p) not locked\n", \
					__FILE__,__LINE__, (x)->module, (x));\
		} \
		(x)->lock = 0; \
	} while (0)
#else
/*
 * gcc versions before ~2.95 have a nasty bug with empty initializers.
 */
#if (__GNUC__ > 2)
  typedef struct { } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { }
#else
  typedef struct { int gcc_is_buggy; } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#endif

/*
 * If CONFIG_SMP is unset, declare the _raw_* definitions as nops
 */
#define spin_lock_init(lock)	do { (void)(lock); } while(0)
#define _raw_spin_lock(lock)	do { (void)(lock); } while(0)
#define spin_is_locked(lock)	((void)(lock), 0)
#define assert_spin_locked(lock)	do { (void)(lock); } while(0)
#define _raw_spin_trylock(lock)	(((void)(lock), 1))
#define spin_unlock_wait(lock)	(void)(lock)
#define _raw_spin_unlock(lock) do { (void)(lock); } while(0)
#endif /* CONFIG_DEBUG_SPINLOCK */

/* RW spinlocks: No debug version */

#if (__GNUC__ > 2)
  typedef struct { } rwlock_t;
  #define RW_LOCK_UNLOCKED (rwlock_t) { }
#else
  typedef struct { int gcc_is_buggy; } rwlock_t;
  #define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
#endif

#define rwlock_init(lock)	do { (void)(lock); } while(0)
#define _raw_read_lock(lock)	do { (void)(lock); } while(0)
#define _raw_read_unlock(lock)	do { (void)(lock); } while(0)
#define _raw_write_lock(lock)	do { (void)(lock); } while(0)
#define _raw_write_unlock(lock)	do { (void)(lock); } while(0)
#define read_can_lock(lock)	(((void)(lock), 1))
#define write_can_lock(lock)	(((void)(lock), 1))
#define _raw_read_trylock(lock) ({ (void)(lock); (1); })
#define _raw_write_trylock(lock) ({ (void)(lock); (1); })

#define _spin_trylock(lock)	({preempt_disable(); _raw_spin_trylock(lock) ? \
				1 : ({preempt_enable(); 0;});})

#define _read_trylock(lock)	({preempt_disable();_raw_read_trylock(lock) ? \
				1 : ({preempt_enable(); 0;});})

#define _write_trylock(lock)	({preempt_disable(); _raw_write_trylock(lock) ? \
				1 : ({preempt_enable(); 0;});})

#define _spin_trylock_bh(lock)	({preempt_disable(); local_bh_disable(); \
				_raw_spin_trylock(lock) ? \
				1 : ({preempt_enable_no_resched(); local_bh_enable(); 0;});})

#define _spin_lock(lock)	\
do { \
	preempt_disable(); \
	_raw_spin_lock(lock); \
	__acquire(lock); \
} while(0)

#define _write_lock(lock) \
do { \
	preempt_disable(); \
	_raw_write_lock(lock); \
	__acquire(lock); \
} while(0)
 
#define _read_lock(lock)	\
do { \
	preempt_disable(); \
	_raw_read_lock(lock); \
	__acquire(lock); \
} while(0)

#define _spin_unlock(lock) \
do { \
	_raw_spin_unlock(lock); \
	preempt_enable(); \
	__release(lock); \
} while (0)

#define _write_unlock(lock) \
do { \
	_raw_write_unlock(lock); \
	preempt_enable(); \
	__release(lock); \
} while(0)

#define _read_unlock(lock) \
do { \
	_raw_read_unlock(lock); \
	preempt_enable(); \
	__release(lock); \
} while(0)

#define _spin_lock_irqsave(lock, flags) \
do {	\
	local_irq_save(flags); \
	preempt_disable(); \
	_raw_spin_lock(lock); \
	__acquire(lock); \
} while (0)

#define _spin_lock_irq(lock) \
do { \
	local_irq_disable(); \
	preempt_disable(); \
	_raw_spin_lock(lock); \
	__acquire(lock); \
} while (0)

#define _spin_lock_bh(lock) \
do { \
	local_bh_disable(); \
	preempt_disable(); \
	_raw_spin_lock(lock); \
	__acquire(lock); \
} while (0)

#define _read_lock_irqsave(lock, flags) \
do {	\
	local_irq_save(flags); \
	preempt_disable(); \
	_raw_read_lock(lock); \
	__acquire(lock); \
} while (0)

#define _read_lock_irq(lock) \
do { \
	local_irq_disable(); \
	preempt_disable(); \
	_raw_read_lock(lock); \
	__acquire(lock); \
} while (0)

#define _read_lock_bh(lock) \
do { \
	local_bh_disable(); \
	preempt_disable(); \
	_raw_read_lock(lock); \
	__acquire(lock); \
} while (0)

#define _write_lock_irqsave(lock, flags) \
do {	\
	local_irq_save(flags); \
	preempt_disable(); \
	_raw_write_lock(lock); \
	__acquire(lock); \
} while (0)

#define _write_lock_irq(lock) \
do { \
	local_irq_disable(); \
	preempt_disable(); \
	_raw_write_lock(lock); \
	__acquire(lock); \
} while (0)

#define _write_lock_bh(lock) \
do { \
	local_bh_disable(); \
	preempt_disable(); \
	_raw_write_lock(lock); \
	__acquire(lock); \
} while (0)

#define _spin_unlock_irqrestore(lock, flags) \
do { \
	_raw_spin_unlock(lock); \
	local_irq_restore(flags); \
	preempt_enable(); \
	__release(lock); \
} while (0)

#define _spin_unlock_irq(lock) \
do { \
	_raw_spin_unlock(lock); \
	local_irq_enable(); \
	preempt_enable(); \
	__release(lock); \
} while (0)

#define _spin_unlock_bh(lock) \
do { \
	_raw_spin_unlock(lock); \
	preempt_enable_no_resched(); \
	local_bh_enable(); \
	__release(lock); \
} while (0)

#define _write_unlock_bh(lock) \
do { \
	_raw_write_unlock(lock); \
	preempt_enable_no_resched(); \
	local_bh_enable(); \
	__release(lock); \
} while (0)

#define _read_unlock_irqrestore(lock, flags) \
do { \
	_raw_read_unlock(lock); \
	local_irq_restore(flags); \
	preempt_enable(); \
	__release(lock); \
} while (0)

#define _write_unlock_irqrestore(lock, flags) \
do { \
	_raw_write_unlock(lock); \
	local_irq_restore(flags); \
	preempt_enable(); \
	__release(lock); \
} while (0)

#define _read_unlock_irq(lock)	\
do { \
	_raw_read_unlock(lock);	\
	local_irq_enable();	\
	preempt_enable();	\
	__release(lock); \
} while (0)

#define _read_unlock_bh(lock)	\
do { \
	_raw_read_unlock(lock);	\
	preempt_enable_no_resched();	\
	local_bh_enable();	\
	__release(lock); \
} while (0)

#define _write_unlock_irq(lock)	\
do { \
	_raw_write_unlock(lock);	\
	local_irq_enable();	\
	preempt_enable();	\
	__release(lock); \
} while (0)

#endif /* !SMP */

/*
 * Define the various spin_lock and rw_lock methods.  Note we define these
 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
 * methods are defined as nops in the case they are not required.
 */
#define spin_trylock(lock)	__cond_lock(_spin_trylock(lock))
#define read_trylock(lock)	__cond_lock(_read_trylock(lock))
#define write_trylock(lock)	__cond_lock(_write_trylock(lock))

#define spin_lock(lock)		_spin_lock(lock)
#define write_lock(lock)	_write_lock(lock)
#define read_lock(lock)		_read_lock(lock)

#ifdef CONFIG_SMP
#define spin_lock_irqsave(lock, flags)	flags = _spin_lock_irqsave(lock)
#define read_lock_irqsave(lock, flags)	flags = _read_lock_irqsave(lock)
#define write_lock_irqsave(lock, flags)	flags = _write_lock_irqsave(lock)
#else
#define spin_lock_irqsave(lock, flags)	_spin_lock_irqsave(lock, flags)
#define read_lock_irqsave(lock, flags)	_read_lock_irqsave(lock, flags)
#define write_lock_irqsave(lock, flags)	_write_lock_irqsave(lock, flags)
#endif

#define spin_lock_irq(lock)		_spin_lock_irq(lock)
#define spin_lock_bh(lock)		_spin_lock_bh(lock)

#define read_lock_irq(lock)		_read_lock_irq(lock)
#define read_lock_bh(lock)		_read_lock_bh(lock)

#define write_lock_irq(lock)		_write_lock_irq(lock)
#define write_lock_bh(lock)		_write_lock_bh(lock)

#define spin_unlock(lock)	_spin_unlock(lock)
#define write_unlock(lock)	_write_unlock(lock)
#define read_unlock(lock)	_read_unlock(lock)

#define spin_unlock_irqrestore(lock, flags)	_spin_unlock_irqrestore(lock, flags)
#define spin_unlock_irq(lock)		_spin_unlock_irq(lock)
#define spin_unlock_bh(lock)		_spin_unlock_bh(lock)

#define read_unlock_irqrestore(lock, flags)	_read_unlock_irqrestore(lock, flags)
#define read_unlock_irq(lock)			_read_unlock_irq(lock)
#define read_unlock_bh(lock)			_read_unlock_bh(lock)

#define write_unlock_irqrestore(lock, flags)	_write_unlock_irqrestore(lock, flags)
#define write_unlock_irq(lock)			_write_unlock_irq(lock)
#define write_unlock_bh(lock)			_write_unlock_bh(lock)

#define spin_trylock_bh(lock)			__cond_lock(_spin_trylock_bh(lock))

#define spin_trylock_irq(lock) \
({ \
	local_irq_disable(); \
	_spin_trylock(lock) ? \
	1 : ({local_irq_enable(); 0; }); \
})

#define spin_trylock_irqsave(lock, flags) \
({ \
	local_irq_save(flags); \
	_spin_trylock(lock) ? \
	1 : ({local_irq_restore(flags); 0;}); \
})

#ifdef CONFIG_LOCKMETER
extern void _metered_spin_lock   (spinlock_t *lock);
extern void _metered_spin_unlock (spinlock_t *lock);
extern int  _metered_spin_trylock(spinlock_t *lock);
extern void _metered_read_lock    (rwlock_t *lock);
extern void _metered_read_unlock  (rwlock_t *lock);
extern void _metered_write_lock   (rwlock_t *lock);
extern void _metered_write_unlock (rwlock_t *lock);
extern int  _metered_read_trylock (rwlock_t *lock);
extern int  _metered_write_trylock(rwlock_t *lock);
#endif

/* "lock on reference count zero" */
#ifndef ATOMIC_DEC_AND_LOCK
#include <asm/atomic.h>
extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
#endif

#define atomic_dec_and_lock(atomic,lock) __cond_lock(_atomic_dec_and_lock(atomic,lock))

/*
 *  bit-based spin_lock()
 *
 * Don't use this unless you really need to: spin_lock() and spin_unlock()
 * are significantly faster.
 */
static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
	/*
	 * Assuming the lock is uncontended, this never enters
	 * the body of the outer loop. If it is contended, then
	 * within the inner loop a non-atomic test is used to
	 * busywait with less bus contention for a good time to
	 * attempt to acquire the lock bit.
	 */
	preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	while (test_and_set_bit(bitnum, addr)) {
		while (test_bit(bitnum, addr)) {
			preempt_enable();
			cpu_relax();
			preempt_disable();
		}
	}
#endif
	__acquire(bitlock);
}

/*
 * Return true if it was acquired
 */
static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
{
	preempt_disable();	
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	if (test_and_set_bit(bitnum, addr)) {
		preempt_enable();
		return 0;
	}
#endif
	__acquire(bitlock);
	return 1;
}

/*
 *  bit-based spin_unlock()
 */
static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
{
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	BUG_ON(!test_bit(bitnum, addr));
	smp_mb__before_clear_bit();
	clear_bit(bitnum, addr);
#endif
	preempt_enable();
	__release(bitlock);
}

/*
 * Return true if the lock is held.
 */
static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
{
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	return test_bit(bitnum, addr);
#elif defined CONFIG_PREEMPT
	return preempt_count();
#else
	return 1;
#endif
}

#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
#define DEFINE_RWLOCK(x) rwlock_t x = RW_LOCK_UNLOCKED

/**
 * spin_can_lock - would spin_trylock() succeed?
 * @lock: the spinlock in question.
 */
#define spin_can_lock(lock)		(!spin_is_locked(lock))

#endif /* __LINUX_SPINLOCK_H */