summaryrefslogtreecommitdiffstats
path: root/include/linux/spinlock.h
blob: a39186194cd6782ac0b6705f02af6179a86f7813 (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
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
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_SPINLOCK_H
#define __LINUX_SPINLOCK_H

/*
 * include/linux/spinlock.h - generic spinlock/rwlock declarations
 *
 * here's the role of the various spinlock/rwlock related include files:
 *
 * on SMP builds:
 *
 *  asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
 *                        initializers
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  asm/spinlock.h:       contains the arch_spin_*()/etc. lowlevel
 *                        implementations, mostly inline assembly code
 *
 *   (also included on UP-debug builds:)
 *
 *  linux/spinlock_api_smp.h:
 *                        contains the prototypes for the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 *
 * on UP builds:
 *
 *  linux/spinlock_type_up.h:
 *                        contains the generic, simplified UP spinlock type.
 *                        (which is an empty structure on non-debug builds)
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  linux/spinlock_up.h:
 *                        contains the arch_spin_*()/etc. version of UP
 *                        builds. (which are NOPs on non-debug, non-preempt
 *                        builds)
 *
 *   (included on UP-non-debug builds:)
 *
 *  linux/spinlock_api_up.h:
 *                        builds the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 */

#include <linux/typecheck.h>
#include <linux/preempt.h>
#include <linux/linkage.h>
#include <linux/compiler.h>
#include <linux/irqflags.h>
#include <linux/thread_info.h>
#include <linux/kernel.h>
#include <linux/stringify.h>
#include <linux/bottom_half.h>
#include <asm/barrier.h>


/*
 * Must define these before including other files, inline functions need them
 */
#define LOCK_SECTION_NAME ".text..lock."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 __attribute__((section(".spinlock.text")))

/*
 * Pull the arch_spinlock_t and arch_rwlock_t definitions:
 */
#include <linux/spinlock_types.h>

/*
 * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
 */
#ifdef CONFIG_SMP
# include <asm/spinlock.h>
#else
# include <linux/spinlock_up.h>
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
  extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
				   struct lock_class_key *key);
# define raw_spin_lock_init(lock)				\
do {								\
	static struct lock_class_key __key;			\
								\
	__raw_spin_lock_init((lock), #lock, &__key);		\
} while (0)

#else
# define raw_spin_lock_init(lock)				\
	do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
#endif

#define raw_spin_is_locked(lock)	arch_spin_is_locked(&(lock)->raw_lock)

#ifdef CONFIG_GENERIC_LOCKBREAK
#define raw_spin_is_contended(lock) ((lock)->break_lock)
#else

#ifdef arch_spin_is_contended
#define raw_spin_is_contended(lock)	arch_spin_is_contended(&(lock)->raw_lock)
#else
#define raw_spin_is_contended(lock)	(((void)(lock), 0))
#endif /*arch_spin_is_contended*/
#endif

/*
 * This barrier must provide two things:
 *
 *   - it must guarantee a STORE before the spin_lock() is ordered against a
 *     LOAD after it, see the comments at its two usage sites.
 *
 *   - it must ensure the critical section is RCsc.
 *
 * The latter is important for cases where we observe values written by other
 * CPUs in spin-loops, without barriers, while being subject to scheduling.
 *
 * CPU0			CPU1			CPU2
 *
 *			for (;;) {
 *			  if (READ_ONCE(X))
 *			    break;
 *			}
 * X=1
 *			<sched-out>
 *						<sched-in>
 *						r = X;
 *
 * without transitivity it could be that CPU1 observes X!=0 breaks the loop,
 * we get migrated and CPU2 sees X==0.
 *
 * Since most load-store architectures implement ACQUIRE with an smp_mb() after
 * the LL/SC loop, they need no further barriers. Similarly all our TSO
 * architectures imply an smp_mb() for each atomic instruction and equally don't
 * need more.
 *
 * Architectures that can implement ACQUIRE better need to take care.
 */
#ifndef smp_mb__after_spinlock
#define smp_mb__after_spinlock()	do { } while (0)
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
 extern int do_raw_spin_trylock(raw_spinlock_t *lock);
 extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
#else
static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
{
	__acquire(lock);
	arch_spin_lock(&lock->raw_lock);
}

#ifndef arch_spin_lock_flags
#define arch_spin_lock_flags(lock, flags)	arch_spin_lock(lock)
#endif

static inline void
do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
{
	__acquire(lock);
	arch_spin_lock_flags(&lock->raw_lock, *flags);
}

static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
{
	return arch_spin_trylock(&(lock)->raw_lock);
}

static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
{
	arch_spin_unlock(&lock->raw_lock);
	__release(lock);
}
#endif

/*
 * Define the various spin_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 raw_spin_trylock(lock)	__cond_lock(lock, _raw_spin_trylock(lock))

#define raw_spin_lock(lock)	_raw_spin_lock(lock)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define raw_spin_lock_nested(lock, subclass) \
	_raw_spin_lock_nested(lock, subclass)

# define raw_spin_lock_nest_lock(lock, nest_lock)			\
	 do {								\
		 typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
		 _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map);	\
	 } while (0)
#else
/*
 * Always evaluate the 'subclass' argument to avoid that the compiler
 * warns about set-but-not-used variables when building with
 * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
 */
# define raw_spin_lock_nested(lock, subclass)		\
	_raw_spin_lock(((void)(subclass), (lock)))
# define raw_spin_lock_nest_lock(lock, nest_lock)	_raw_spin_lock(lock)
#endif

#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)

#define raw_spin_lock_irqsave(lock, flags)			\
	do {						\
		typecheck(unsigned long, flags);	\
		flags = _raw_spin_lock_irqsave(lock);	\
	} while (0)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
#define raw_spin_lock_irqsave_nested(lock, flags, subclass)		\
	do {								\
		typecheck(unsigned long, flags);			\
		flags = _raw_spin_lock_irqsave_nested(lock, subclass);	\
	} while (0)
#else
#define raw_spin_lock_irqsave_nested(lock, flags, subclass)		\
	do {								\
		typecheck(unsigned long, flags);			\
		flags = _raw_spin_lock_irqsave(lock);			\
	} while (0)
#endif

#else

#define raw_spin_lock_irqsave(lock, flags)		\
	do {						\
		typecheck(unsigned long, flags);	\
		_raw_spin_lock_irqsave(lock, flags);	\
	} while (0)

#define raw_spin_lock_irqsave_nested(lock, flags, subclass)	\
	raw_spin_lock_irqsave(lock, flags)

#endif

#define raw_spin_lock_irq(lock)		_raw_spin_lock_irq(lock)
#define raw_spin_lock_bh(lock)		_raw_spin_lock_bh(lock)
#define raw_spin_unlock(lock)		_raw_spin_unlock(lock)
#define raw_spin_unlock_irq(lock)	_raw_spin_unlock_irq(lock)

#define raw_spin_unlock_irqrestore(lock, flags)		\
	do {							\
		typecheck(unsigned long, flags);		\
		_raw_spin_unlock_irqrestore(lock, flags);	\
	} while (0)
#define raw_spin_unlock_bh(lock)	_raw_spin_unlock_bh(lock)

#define raw_spin_trylock_bh(lock) \
	__cond_lock(lock, _raw_spin_trylock_bh(lock))

#define raw_spin_trylock_irq(lock) \
({ \
	local_irq_disable(); \
	raw_spin_trylock(lock) ? \
	1 : ({ local_irq_enable(); 0;  }); \
})

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

/* Include rwlock functions */
#include <linux/rwlock.h>

/*
 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
 */
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
# include <linux/spinlock_api_smp.h>
#else
# include <linux/spinlock_api_up.h>
#endif

/*
 * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
 */

static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
{
	return &lock->rlock;
}

#define spin_lock_init(_lock)				\
do {							\
	spinlock_check(_lock);				\
	raw_spin_lock_init(&(_lock)->rlock);		\
} while (0)

static __always_inline void spin_lock(spinlock_t *lock)
{
	raw_spin_lock(&lock->rlock);
}

static __always_inline void spin_lock_bh(spinlock_t *lock)
{
	raw_spin_lock_bh(&lock->rlock);
}

static __always_inline int spin_trylock(spinlock_t *lock)
{
	return raw_spin_trylock(&lock->rlock);
}

#define spin_lock_nested(lock, subclass)			\
do {								\
	raw_spin_lock_nested(spinlock_check(lock), subclass);	\
} while (0)

#define spin_lock_nest_lock(lock, nest_lock)				\
do {									\
	raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);	\
} while (0)

static __always_inline void spin_lock_irq(spinlock_t *lock)
{
	raw_spin_lock_irq(&lock->rlock);
}

#define spin_lock_irqsave(lock, flags)				\
do {								\
	raw_spin_lock_irqsave(spinlock_check(lock), flags);	\
} while (0)

#define spin_lock_irqsave_nested(lock, flags, subclass)			\
do {									\
	raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
} while (0)

static __always_inline void spin_unlock(spinlock_t *lock)
{
	raw_spin_unlock(&lock->rlock);
}

static __always_inline void spin_unlock_bh(spinlock_t *lock)
{
	raw_spin_unlock_bh(&lock->rlock);
}

static __always_inline void spin_unlock_irq(spinlock_t *lock)
{
	raw_spin_unlock_irq(&lock->rlock);
}

static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
{
	raw_spin_unlock_irqrestore(&lock->rlock, flags);
}

static __always_inline int spin_trylock_bh(spinlock_t *lock)
{
	return raw_spin_trylock_bh(&lock->rlock);
}

static __always_inline int spin_trylock_irq(spinlock_t *lock)
{
	return raw_spin_trylock_irq(&lock->rlock);
}

#define spin_trylock_irqsave(lock, flags)			\
({								\
	raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
})

static __always_inline int spin_is_locked(spinlock_t *lock)
{
	return raw_spin_is_locked(&lock->rlock);
}

static __always_inline int spin_is_contended(spinlock_t *lock)
{
	return raw_spin_is_contended(&lock->rlock);
}

#define assert_spin_locked(lock)	assert_raw_spin_locked(&(lock)->rlock)

/*
 * Pull the atomic_t declaration:
 * (asm-mips/atomic.h needs above definitions)
 */
#include <linux/atomic.h>
/**
 * atomic_dec_and_lock - lock on reaching reference count zero
 * @atomic: the atomic counter
 * @lock: the spinlock in question
 *
 * Decrements @atomic by 1.  If the result is 0, returns true and locks
 * @lock.  Returns false for all other cases.
 */
extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
#define atomic_dec_and_lock(atomic, lock) \
		__cond_lock(lock, _atomic_dec_and_lock(atomic, lock))

#endif /* __LINUX_SPINLOCK_H */
OpenPOWER on IntegriCloud