Root/kernel/spinlock.c

1/*
2 * Copyright (2004) Linus Torvalds
3 *
4 * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
5 *
6 * Copyright (2004, 2005) Ingo Molnar
7 *
8 * This file contains the spinlock/rwlock implementations for the
9 * SMP and the DEBUG_SPINLOCK cases. (UP-nondebug inlines them)
10 *
11 * Note that some architectures have special knowledge about the
12 * stack frames of these functions in their profile_pc. If you
13 * change anything significant here that could change the stack
14 * frame contact the architecture maintainers.
15 */
16
17#include <linux/linkage.h>
18#include <linux/preempt.h>
19#include <linux/spinlock.h>
20#include <linux/interrupt.h>
21#include <linux/debug_locks.h>
22#include <linux/module.h>
23
24/*
25 * If lockdep is enabled then we use the non-preemption spin-ops
26 * even on CONFIG_PREEMPT, because lockdep assumes that interrupts are
27 * not re-enabled during lock-acquire (which the preempt-spin-ops do):
28 */
29#if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
30/*
31 * The __lock_function inlines are taken from
32 * include/linux/spinlock_api_smp.h
33 */
34#else
35#define raw_read_can_lock(l) read_can_lock(l)
36#define raw_write_can_lock(l) write_can_lock(l)
37/*
38 * We build the __lock_function inlines here. They are too large for
39 * inlining all over the place, but here is only one user per function
40 * which embedds them into the calling _lock_function below.
41 *
42 * This could be a long-held lock. We both prepare to spin for a long
43 * time (making _this_ CPU preemptable if possible), and we also signal
44 * towards that other CPU that it should break the lock ASAP.
45 */
46#define BUILD_LOCK_OPS(op, locktype) \
47void __lockfunc __raw_##op##_lock(locktype##_t *lock) \
48{ \
49    for (;;) { \
50        preempt_disable(); \
51        if (likely(do_raw_##op##_trylock(lock))) \
52            break; \
53        preempt_enable(); \
54                                    \
55        if (!(lock)->break_lock) \
56            (lock)->break_lock = 1; \
57        while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
58            arch_##op##_relax(&lock->raw_lock); \
59    } \
60    (lock)->break_lock = 0; \
61} \
62                                    \
63unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \
64{ \
65    unsigned long flags; \
66                                    \
67    for (;;) { \
68        preempt_disable(); \
69        local_irq_save(flags); \
70        if (likely(do_raw_##op##_trylock(lock))) \
71            break; \
72        local_irq_restore(flags); \
73        preempt_enable(); \
74                                    \
75        if (!(lock)->break_lock) \
76            (lock)->break_lock = 1; \
77        while (!raw_##op##_can_lock(lock) && (lock)->break_lock)\
78            arch_##op##_relax(&lock->raw_lock); \
79    } \
80    (lock)->break_lock = 0; \
81    return flags; \
82} \
83                                    \
84void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock) \
85{ \
86    _raw_##op##_lock_irqsave(lock); \
87} \
88                                    \
89void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock) \
90{ \
91    unsigned long flags; \
92                                    \
93    /* */ \
94    /* Careful: we must exclude softirqs too, hence the */ \
95    /* irq-disabling. We use the generic preemption-aware */ \
96    /* function: */ \
97    /**/ \
98    flags = _raw_##op##_lock_irqsave(lock); \
99    local_bh_disable(); \
100    local_irq_restore(flags); \
101} \
102
103/*
104 * Build preemption-friendly versions of the following
105 * lock-spinning functions:
106 *
107 * __[spin|read|write]_lock()
108 * __[spin|read|write]_lock_irq()
109 * __[spin|read|write]_lock_irqsave()
110 * __[spin|read|write]_lock_bh()
111 */
112BUILD_LOCK_OPS(spin, raw_spinlock);
113BUILD_LOCK_OPS(read, rwlock);
114BUILD_LOCK_OPS(write, rwlock);
115
116#endif
117
118#ifndef CONFIG_INLINE_SPIN_TRYLOCK
119int __lockfunc _raw_spin_trylock(raw_spinlock_t *lock)
120{
121    return __raw_spin_trylock(lock);
122}
123EXPORT_SYMBOL(_raw_spin_trylock);
124#endif
125
126#ifndef CONFIG_INLINE_SPIN_TRYLOCK_BH
127int __lockfunc _raw_spin_trylock_bh(raw_spinlock_t *lock)
128{
129    return __raw_spin_trylock_bh(lock);
130}
131EXPORT_SYMBOL(_raw_spin_trylock_bh);
132#endif
133
134#ifndef CONFIG_INLINE_SPIN_LOCK
135void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)
136{
137    __raw_spin_lock(lock);
138}
139EXPORT_SYMBOL(_raw_spin_lock);
140#endif
141
142#ifndef CONFIG_INLINE_SPIN_LOCK_IRQSAVE
143unsigned long __lockfunc _raw_spin_lock_irqsave(raw_spinlock_t *lock)
144{
145    return __raw_spin_lock_irqsave(lock);
146}
147EXPORT_SYMBOL(_raw_spin_lock_irqsave);
148#endif
149
150#ifndef CONFIG_INLINE_SPIN_LOCK_IRQ
151void __lockfunc _raw_spin_lock_irq(raw_spinlock_t *lock)
152{
153    __raw_spin_lock_irq(lock);
154}
155EXPORT_SYMBOL(_raw_spin_lock_irq);
156#endif
157
158#ifndef CONFIG_INLINE_SPIN_LOCK_BH
159void __lockfunc _raw_spin_lock_bh(raw_spinlock_t *lock)
160{
161    __raw_spin_lock_bh(lock);
162}
163EXPORT_SYMBOL(_raw_spin_lock_bh);
164#endif
165
166#ifndef CONFIG_INLINE_SPIN_UNLOCK
167void __lockfunc _raw_spin_unlock(raw_spinlock_t *lock)
168{
169    __raw_spin_unlock(lock);
170}
171EXPORT_SYMBOL(_raw_spin_unlock);
172#endif
173
174#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE
175void __lockfunc _raw_spin_unlock_irqrestore(raw_spinlock_t *lock, unsigned long flags)
176{
177    __raw_spin_unlock_irqrestore(lock, flags);
178}
179EXPORT_SYMBOL(_raw_spin_unlock_irqrestore);
180#endif
181
182#ifndef CONFIG_INLINE_SPIN_UNLOCK_IRQ
183void __lockfunc _raw_spin_unlock_irq(raw_spinlock_t *lock)
184{
185    __raw_spin_unlock_irq(lock);
186}
187EXPORT_SYMBOL(_raw_spin_unlock_irq);
188#endif
189
190#ifndef CONFIG_INLINE_SPIN_UNLOCK_BH
191void __lockfunc _raw_spin_unlock_bh(raw_spinlock_t *lock)
192{
193    __raw_spin_unlock_bh(lock);
194}
195EXPORT_SYMBOL(_raw_spin_unlock_bh);
196#endif
197
198#ifndef CONFIG_INLINE_READ_TRYLOCK
199int __lockfunc _raw_read_trylock(rwlock_t *lock)
200{
201    return __raw_read_trylock(lock);
202}
203EXPORT_SYMBOL(_raw_read_trylock);
204#endif
205
206#ifndef CONFIG_INLINE_READ_LOCK
207void __lockfunc _raw_read_lock(rwlock_t *lock)
208{
209    __raw_read_lock(lock);
210}
211EXPORT_SYMBOL(_raw_read_lock);
212#endif
213
214#ifndef CONFIG_INLINE_READ_LOCK_IRQSAVE
215unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
216{
217    return __raw_read_lock_irqsave(lock);
218}
219EXPORT_SYMBOL(_raw_read_lock_irqsave);
220#endif
221
222#ifndef CONFIG_INLINE_READ_LOCK_IRQ
223void __lockfunc _raw_read_lock_irq(rwlock_t *lock)
224{
225    __raw_read_lock_irq(lock);
226}
227EXPORT_SYMBOL(_raw_read_lock_irq);
228#endif
229
230#ifndef CONFIG_INLINE_READ_LOCK_BH
231void __lockfunc _raw_read_lock_bh(rwlock_t *lock)
232{
233    __raw_read_lock_bh(lock);
234}
235EXPORT_SYMBOL(_raw_read_lock_bh);
236#endif
237
238#ifndef CONFIG_INLINE_READ_UNLOCK
239void __lockfunc _raw_read_unlock(rwlock_t *lock)
240{
241    __raw_read_unlock(lock);
242}
243EXPORT_SYMBOL(_raw_read_unlock);
244#endif
245
246#ifndef CONFIG_INLINE_READ_UNLOCK_IRQRESTORE
247void __lockfunc _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
248{
249    __raw_read_unlock_irqrestore(lock, flags);
250}
251EXPORT_SYMBOL(_raw_read_unlock_irqrestore);
252#endif
253
254#ifndef CONFIG_INLINE_READ_UNLOCK_IRQ
255void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)
256{
257    __raw_read_unlock_irq(lock);
258}
259EXPORT_SYMBOL(_raw_read_unlock_irq);
260#endif
261
262#ifndef CONFIG_INLINE_READ_UNLOCK_BH
263void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)
264{
265    __raw_read_unlock_bh(lock);
266}
267EXPORT_SYMBOL(_raw_read_unlock_bh);
268#endif
269
270#ifndef CONFIG_INLINE_WRITE_TRYLOCK
271int __lockfunc _raw_write_trylock(rwlock_t *lock)
272{
273    return __raw_write_trylock(lock);
274}
275EXPORT_SYMBOL(_raw_write_trylock);
276#endif
277
278#ifndef CONFIG_INLINE_WRITE_LOCK
279void __lockfunc _raw_write_lock(rwlock_t *lock)
280{
281    __raw_write_lock(lock);
282}
283EXPORT_SYMBOL(_raw_write_lock);
284#endif
285
286#ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE
287unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
288{
289    return __raw_write_lock_irqsave(lock);
290}
291EXPORT_SYMBOL(_raw_write_lock_irqsave);
292#endif
293
294#ifndef CONFIG_INLINE_WRITE_LOCK_IRQ
295void __lockfunc _raw_write_lock_irq(rwlock_t *lock)
296{
297    __raw_write_lock_irq(lock);
298}
299EXPORT_SYMBOL(_raw_write_lock_irq);
300#endif
301
302#ifndef CONFIG_INLINE_WRITE_LOCK_BH
303void __lockfunc _raw_write_lock_bh(rwlock_t *lock)
304{
305    __raw_write_lock_bh(lock);
306}
307EXPORT_SYMBOL(_raw_write_lock_bh);
308#endif
309
310#ifndef CONFIG_INLINE_WRITE_UNLOCK
311void __lockfunc _raw_write_unlock(rwlock_t *lock)
312{
313    __raw_write_unlock(lock);
314}
315EXPORT_SYMBOL(_raw_write_unlock);
316#endif
317
318#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE
319void __lockfunc _raw_write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
320{
321    __raw_write_unlock_irqrestore(lock, flags);
322}
323EXPORT_SYMBOL(_raw_write_unlock_irqrestore);
324#endif
325
326#ifndef CONFIG_INLINE_WRITE_UNLOCK_IRQ
327void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)
328{
329    __raw_write_unlock_irq(lock);
330}
331EXPORT_SYMBOL(_raw_write_unlock_irq);
332#endif
333
334#ifndef CONFIG_INLINE_WRITE_UNLOCK_BH
335void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)
336{
337    __raw_write_unlock_bh(lock);
338}
339EXPORT_SYMBOL(_raw_write_unlock_bh);
340#endif
341
342#ifdef CONFIG_DEBUG_LOCK_ALLOC
343
344void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
345{
346    preempt_disable();
347    spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
348    LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
349}
350EXPORT_SYMBOL(_raw_spin_lock_nested);
351
352unsigned long __lockfunc _raw_spin_lock_irqsave_nested(raw_spinlock_t *lock,
353                           int subclass)
354{
355    unsigned long flags;
356
357    local_irq_save(flags);
358    preempt_disable();
359    spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
360    LOCK_CONTENDED_FLAGS(lock, do_raw_spin_trylock, do_raw_spin_lock,
361                do_raw_spin_lock_flags, &flags);
362    return flags;
363}
364EXPORT_SYMBOL(_raw_spin_lock_irqsave_nested);
365
366void __lockfunc _raw_spin_lock_nest_lock(raw_spinlock_t *lock,
367                     struct lockdep_map *nest_lock)
368{
369    preempt_disable();
370    spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
371    LOCK_CONTENDED(lock, do_raw_spin_trylock, do_raw_spin_lock);
372}
373EXPORT_SYMBOL(_raw_spin_lock_nest_lock);
374
375#endif
376
377notrace int in_lock_functions(unsigned long addr)
378{
379    /* Linker adds these: start and end of __lockfunc functions */
380    extern char __lock_text_start[], __lock_text_end[];
381
382    return addr >= (unsigned long)__lock_text_start
383    && addr < (unsigned long)__lock_text_end;
384}
385EXPORT_SYMBOL(in_lock_functions);
386

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