1 #ifndef __LINUX_SPINLOCK_H
2 #define __LINUX_SPINLOCK_H
3
4 /*
5 * include/linux/spinlock.h - generic spinlock/rwlock declarations
6 *
7 * here's the role of the various spinlock/rwlock related include files:
8 *
9 * on SMP builds:
10 *
11 * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the
12 * initializers
13 *
14 * linux/spinlock_types.h:
15 * defines the generic type and initializers
16 *
17 * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel
18 * implementations, mostly inline assembly code
19 *
20 * (also included on UP-debug builds:)
21 *
22 * linux/spinlock_api_smp.h:
23 * contains the prototypes for the _spin_*() APIs.
24 *
25 * linux/spinlock.h: builds the final spin_*() APIs.
26 *
27 * on UP builds:
28 *
29 * linux/spinlock_type_up.h:
30 * contains the generic, simplified UP spinlock type.
31 * (which is an empty structure on non-debug builds)
32 *
33 * linux/spinlock_types.h:
34 * defines the generic type and initializers
35 *
36 * linux/spinlock_up.h:
37 * contains the __raw_spin_*()/etc. version of UP
38 * builds. (which are NOPs on non-debug, non-preempt
39 * builds)
40 *
41 * (included on UP-non-debug builds:)
42 *
43 * linux/spinlock_api_up.h:
44 * builds the _spin_*() APIs.
45 *
46 * linux/spinlock.h: builds the final spin_*() APIs.
47 */
48
49 #include <linux/preempt.h>
50 #include <linux/linkage.h>
51 #include <linux/compiler.h>
52 #include <linux/thread_info.h>
53 #include <linux/kernel.h>
54 #include <linux/stringify.h>
55 #include <linux/bottom_half.h>
56
57 #include <asm/system.h>
58
59 /*
60 * Must define these before including other files, inline functions need them
61 */
62 #define LOCK_SECTION_NAME ".text.lock."KBUILD_BASENAME
63
64 #define LOCK_SECTION_START(extra) \
65 ".subsection 1\n\t" \
66 extra \
67 ".ifndef " LOCK_SECTION_NAME "\n\t" \
68 LOCK_SECTION_NAME ":\n\t" \
69 ".endif\n"
70
71 #define LOCK_SECTION_END \
72 ".previous\n\t"
73
74 #define __lockfunc __attribute__((section(".spinlock.text")))
75
76 /*
77 * Pull the raw_spinlock_t and raw_rwlock_t definitions:
78 */
79 #include <linux/spinlock_types.h>
80
81 extern int __lockfunc generic__raw_read_trylock(raw_rwlock_t *lock);
82
83 /*
84 * Pull the __raw*() functions/declarations (UP-nondebug doesnt need them):
85 */
86 #ifdef CONFIG_SMP
87 # include <asm/spinlock.h>
88 #else
89 # include <linux/spinlock_up.h>
90 #endif
91
92 #ifdef CONFIG_DEBUG_SPINLOCK
93 extern void __spin_lock_init(spinlock_t *lock, const char *name,
94 struct lock_class_key *key);
95 # define spin_lock_init(lock) \
96 do { \
97 static struct lock_class_key __key; \
98 \
99 __spin_lock_init((lock), #lock, &__key); \
100 } while (0)
101
102 #else
103 # define spin_lock_init(lock) \
104 do { *(lock) = SPIN_LOCK_UNLOCKED; } while (0)
105 #endif
106
107 #ifdef CONFIG_DEBUG_SPINLOCK
108 extern void __rwlock_init(rwlock_t *lock, const char *name,
109 struct lock_class_key *key);
110 # define rwlock_init(lock) \
111 do { \
112 static struct lock_class_key __key; \
113 \
114 __rwlock_init((lock), #lock, &__key); \
115 } while (0)
116 #else
117 # define rwlock_init(lock) \
118 do { *(lock) = RW_LOCK_UNLOCKED; } while (0)
119 #endif
120
121 #define spin_is_locked(lock) __raw_spin_is_locked(&(lock)->raw_lock)
122
123 #ifdef CONFIG_GENERIC_LOCKBREAK
124 #define spin_is_contended(lock) ((lock)->break_lock)
125 #else
126 #define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
127 #endif
128
129 /**
130 * spin_unlock_wait - wait until the spinlock gets unlocked
131 * @lock: the spinlock in question.
132 */
133 #define spin_unlock_wait(lock) __raw_spin_unlock_wait(&(lock)->raw_lock)
134
135 /*
136 * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
137 */
138 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
139 # include <linux/spinlock_api_smp.h>
140 #else
141 # include <linux/spinlock_api_up.h>
142 #endif
143
144 #ifdef CONFIG_DEBUG_SPINLOCK
145 extern void _raw_spin_lock(spinlock_t *lock);
146 #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
147 extern int _raw_spin_trylock(spinlock_t *lock);
148 extern void _raw_spin_unlock(spinlock_t *lock);
149 extern void _raw_read_lock(rwlock_t *lock);
150 extern int _raw_read_trylock(rwlock_t *lock);
151 extern void _raw_read_unlock(rwlock_t *lock);
152 extern void _raw_write_lock(rwlock_t *lock);
153 extern int _raw_write_trylock(rwlock_t *lock);
154 extern void _raw_write_unlock(rwlock_t *lock);
155 #else
156 # define _raw_spin_lock(lock) __raw_spin_lock(&(lock)->raw_lock)
157 # define _raw_spin_lock_flags(lock, flags) \
158 __raw_spin_lock_flags(&(lock)->raw_lock, *(flags))
159 # define _raw_spin_trylock(lock) __raw_spin_trylock(&(lock)->raw_lock)
160 # define _raw_spin_unlock(lock) __raw_spin_unlock(&(lock)->raw_lock)
161 # define _raw_read_lock(rwlock) __raw_read_lock(&(rwlock)->raw_lock)
162 # define _raw_read_trylock(rwlock) __raw_read_trylock(&(rwlock)->raw_lock)
163 # define _raw_read_unlock(rwlock) __raw_read_unlock(&(rwlock)->raw_lock)
164 # define _raw_write_lock(rwlock) __raw_write_lock(&(rwlock)->raw_lock)
165 # define _raw_write_trylock(rwlock) __raw_write_trylock(&(rwlock)->raw_lock)
166 # define _raw_write_unlock(rwlock) __raw_write_unlock(&(rwlock)->raw_lock)
167 #endif
168
169 #define read_can_lock(rwlock) __raw_read_can_lock(&(rwlock)->raw_lock)
170 #define write_can_lock(rwlock) __raw_write_can_lock(&(rwlock)->raw_lock)
171
172 /*
173 * Define the various spin_lock and rw_lock methods. Note we define these
174 * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
175 * methods are defined as nops in the case they are not required.
176 */
177 #define spin_trylock(lock) __cond_lock(lock, _spin_trylock(lock))
178 #define read_trylock(lock) __cond_lock(lock, _read_trylock(lock))
179 #define write_trylock(lock) __cond_lock(lock, _write_trylock(lock))
180
181 #define spin_lock(lock) _spin_lock(lock)
182
183 #ifdef CONFIG_DEBUG_LOCK_ALLOC
184 # define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
185 #else
186 # define spin_lock_nested(lock, subclass) _spin_lock(lock)
187 #endif
188
189 #define write_lock(lock) _write_lock(lock)
190 #define read_lock(lock) _read_lock(lock)
191
192 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
193
194 #define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
195 #define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
196 #define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
197
198 #ifdef CONFIG_DEBUG_LOCK_ALLOC
199 #define spin_lock_irqsave_nested(lock, flags, subclass) \
200 flags = _spin_lock_irqsave_nested(lock, subclass)
201 #else
202 #define spin_lock_irqsave_nested(lock, flags, subclass) \
203 flags = _spin_lock_irqsave(lock)
204 #endif
205
206 #else
207
208 #define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
209 #define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
210 #define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
211 #define spin_lock_irqsave_nested(lock, flags, subclass) \
212 spin_lock_irqsave(lock, flags)
213
214 #endif
215
216 #define spin_lock_irq(lock) _spin_lock_irq(lock)
217 #define spin_lock_bh(lock) _spin_lock_bh(lock)
218
219 #define read_lock_irq(lock) _read_lock_irq(lock)
220 #define read_lock_bh(lock) _read_lock_bh(lock)
221
222 #define write_lock_irq(lock) _write_lock_irq(lock)
223 #define write_lock_bh(lock) _write_lock_bh(lock)
224
225 /*
226 * We inline the unlock functions in the nondebug case:
227 */
228 #if defined(CONFIG_DEBUG_SPINLOCK) || defined(CONFIG_PREEMPT) || \
229 !defined(CONFIG_SMP)
230 # define spin_unlock(lock) _spin_unlock(lock)
231 # define read_unlock(lock) _read_unlock(lock)
232 # define write_unlock(lock) _write_unlock(lock)
233 # define spin_unlock_irq(lock) _spin_unlock_irq(lock)
234 # define read_unlock_irq(lock) _read_unlock_irq(lock)
235 # define write_unlock_irq(lock) _write_unlock_irq(lock)
236 #else
237 # define spin_unlock(lock) \
238 do {__raw_spin_unlock(&(lock)->raw_lock); __release(lock); } while (0)
239 # define read_unlock(lock) \
240 do {__raw_read_unlock(&(lock)->raw_lock); __release(lock); } while (0)
241 # define write_unlock(lock) \
242 do {__raw_write_unlock(&(lock)->raw_lock); __release(lock); } while (0)
243 # define spin_unlock_irq(lock) \
244 do { \
245 __raw_spin_unlock(&(lock)->raw_lock); \
246 __release(lock); \
247 local_irq_enable(); \
248 } while (0)
249 # define read_unlock_irq(lock) \
250 do { \
251 __raw_read_unlock(&(lock)->raw_lock); \
252 __release(lock); \
253 local_irq_enable(); \
254 } while (0)
255 # define write_unlock_irq(lock) \
256 do { \
257 __raw_write_unlock(&(lock)->raw_lock); \
258 __release(lock); \
259 local_irq_enable(); \
260 } while (0)
261 #endif
262
263 #define spin_unlock_irqrestore(lock, flags) \
264 _spin_unlock_irqrestore(lock, flags)
265 #define spin_unlock_bh(lock) _spin_unlock_bh(lock)
266
267 #define read_unlock_irqrestore(lock, flags) \
268 _read_unlock_irqrestore(lock, flags)
269 #define read_unlock_bh(lock) _read_unlock_bh(lock)
270
271 #define write_unlock_irqrestore(lock, flags) \
272 _write_unlock_irqrestore(lock, flags)
273 #define write_unlock_bh(lock) _write_unlock_bh(lock)
274
275 #define spin_trylock_bh(lock) __cond_lock(lock, _spin_trylock_bh(lock))
276
277 #define spin_trylock_irq(lock) \
278 ({ \
279 local_irq_disable(); \
280 spin_trylock(lock) ? \
281 1 : ({ local_irq_enable(); 0; }); \
282 })
283
284 #define spin_trylock_irqsave(lock, flags) \
285 ({ \
286 local_irq_save(flags); \
287 spin_trylock(lock) ? \
288 1 : ({ local_irq_restore(flags); 0; }); \
289 })
290
291 #define write_trylock_irqsave(lock, flags) \
292 ({ \
293 local_irq_save(flags); \
294 write_trylock(lock) ? \
295 1 : ({ local_irq_restore(flags); 0; }); \
296 })
297
298 /*
299 * Locks two spinlocks l1 and l2.
300 * l1_first indicates if spinlock l1 should be taken first.
301 */
302 static inline void double_spin_lock(spinlock_t *l1, spinlock_t *l2,
303 bool l1_first)
304 __acquires(l1)
305 __acquires(l2)
306 {
307 if (l1_first) {
308 spin_lock(l1);
309 spin_lock(l2);
310 } else {
311 spin_lock(l2);
312 spin_lock(l1);
313 }
314 }
315
316 /*
317 * Unlocks two spinlocks l1 and l2.
318 * l1_taken_first indicates if spinlock l1 was taken first and therefore
319 * should be released after spinlock l2.
320 */
321 static inline void double_spin_unlock(spinlock_t *l1, spinlock_t *l2,
322 bool l1_taken_first)
323 __releases(l1)
324 __releases(l2)
325 {
326 if (l1_taken_first) {
327 spin_unlock(l2);
328 spin_unlock(l1);
329 } else {
330 spin_unlock(l1);
331 spin_unlock(l2);
332 }
333 }
334
335 /*
336 * Pull the atomic_t declaration:
337 * (asm-mips/atomic.h needs above definitions)
338 */
339 #include <asm/atomic.h>
340 /**
341 * atomic_dec_and_lock - lock on reaching reference count zero
342 * @atomic: the atomic counter
343 * @lock: the spinlock in question
344 *
345 * Decrements @atomic by 1. If the result is 0, returns true and locks
346 * @lock. Returns false for all other cases.
347 */
348 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
349 #define atomic_dec_and_lock(atomic, lock) \
350 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
351
352 /**
353 * spin_can_lock - would spin_trylock() succeed?
354 * @lock: the spinlock in question.
355 */
356 #define spin_can_lock(lock) (!spin_is_locked(lock))
357
358 #endif /* __LINUX_SPINLOCK_H */
359
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