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TOMOYO Linux Cross Reference
Linux/include/linux/spinlock.h

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  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 arch_spinlock_t/arch_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 arch_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 arch_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/typecheck.h>
 50 #include <linux/preempt.h>
 51 #include <linux/linkage.h>
 52 #include <linux/compiler.h>
 53 #include <linux/irqflags.h>
 54 #include <linux/thread_info.h>
 55 #include <linux/kernel.h>
 56 #include <linux/stringify.h>
 57 #include <linux/bottom_half.h>
 58 #include <asm/barrier.h>
 59 
 60 
 61 /*
 62  * Must define these before including other files, inline functions need them
 63  */
 64 #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
 65 
 66 #define LOCK_SECTION_START(extra)               \
 67         ".subsection 1\n\t"                     \
 68         extra                                   \
 69         ".ifndef " LOCK_SECTION_NAME "\n\t"     \
 70         LOCK_SECTION_NAME ":\n\t"               \
 71         ".endif\n"
 72 
 73 #define LOCK_SECTION_END                        \
 74         ".previous\n\t"
 75 
 76 #define __lockfunc __attribute__((section(".spinlock.text")))
 77 
 78 /*
 79  * Pull the arch_spinlock_t and arch_rwlock_t definitions:
 80  */
 81 #include <linux/spinlock_types.h>
 82 
 83 /*
 84  * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't 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 __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
 94                                    struct lock_class_key *key);
 95 # define raw_spin_lock_init(lock)                               \
 96 do {                                                            \
 97         static struct lock_class_key __key;                     \
 98                                                                 \
 99         __raw_spin_lock_init((lock), #lock, &__key);            \
100 } while (0)
101 
102 #else
103 # define raw_spin_lock_init(lock)                               \
104         do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
105 #endif
106 
107 #define raw_spin_is_locked(lock)        arch_spin_is_locked(&(lock)->raw_lock)
108 
109 #ifdef CONFIG_GENERIC_LOCKBREAK
110 #define raw_spin_is_contended(lock) ((lock)->break_lock)
111 #else
112 
113 #ifdef arch_spin_is_contended
114 #define raw_spin_is_contended(lock)     arch_spin_is_contended(&(lock)->raw_lock)
115 #else
116 #define raw_spin_is_contended(lock)     (((void)(lock), 0))
117 #endif /*arch_spin_is_contended*/
118 #endif
119 
120 /*
121  * Despite its name it doesn't necessarily has to be a full barrier.
122  * It should only guarantee that a STORE before the critical section
123  * can not be reordered with a LOAD inside this section.
124  * spin_lock() is the one-way barrier, this LOAD can not escape out
125  * of the region. So the default implementation simply ensures that
126  * a STORE can not move into the critical section, smp_wmb() should
127  * serialize it with another STORE done by spin_lock().
128  */
129 #ifndef smp_mb__before_spinlock
130 #define smp_mb__before_spinlock()       smp_wmb()
131 #endif
132 
133 /*
134  * Place this after a lock-acquisition primitive to guarantee that
135  * an UNLOCK+LOCK pair act as a full barrier.  This guarantee applies
136  * if the UNLOCK and LOCK are executed by the same CPU or if the
137  * UNLOCK and LOCK operate on the same lock variable.
138  */
139 #ifndef smp_mb__after_unlock_lock
140 #define smp_mb__after_unlock_lock()     do { } while (0)
141 #endif
142 
143 /**
144  * raw_spin_unlock_wait - wait until the spinlock gets unlocked
145  * @lock: the spinlock in question.
146  */
147 #define raw_spin_unlock_wait(lock)      arch_spin_unlock_wait(&(lock)->raw_lock)
148 
149 #ifdef CONFIG_DEBUG_SPINLOCK
150  extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
151 #define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
152  extern int do_raw_spin_trylock(raw_spinlock_t *lock);
153  extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
154 #else
155 static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
156 {
157         __acquire(lock);
158         arch_spin_lock(&lock->raw_lock);
159 }
160 
161 static inline void
162 do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
163 {
164         __acquire(lock);
165         arch_spin_lock_flags(&lock->raw_lock, *flags);
166 }
167 
168 static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
169 {
170         return arch_spin_trylock(&(lock)->raw_lock);
171 }
172 
173 static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
174 {
175         arch_spin_unlock(&lock->raw_lock);
176         __release(lock);
177 }
178 #endif
179 
180 /*
181  * Define the various spin_lock methods.  Note we define these
182  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
183  * various methods are defined as nops in the case they are not
184  * required.
185  */
186 #define raw_spin_trylock(lock)  __cond_lock(lock, _raw_spin_trylock(lock))
187 
188 #define raw_spin_lock(lock)     _raw_spin_lock(lock)
189 
190 #ifdef CONFIG_DEBUG_LOCK_ALLOC
191 # define raw_spin_lock_nested(lock, subclass) \
192         _raw_spin_lock_nested(lock, subclass)
193 
194 # define raw_spin_lock_nest_lock(lock, nest_lock)                       \
195          do {                                                           \
196                  typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
197                  _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
198          } while (0)
199 #else
200 # define raw_spin_lock_nested(lock, subclass)           _raw_spin_lock(lock)
201 # define raw_spin_lock_nest_lock(lock, nest_lock)       _raw_spin_lock(lock)
202 #endif
203 
204 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
205 
206 #define raw_spin_lock_irqsave(lock, flags)                      \
207         do {                                            \
208                 typecheck(unsigned long, flags);        \
209                 flags = _raw_spin_lock_irqsave(lock);   \
210         } while (0)
211 
212 #ifdef CONFIG_DEBUG_LOCK_ALLOC
213 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
214         do {                                                            \
215                 typecheck(unsigned long, flags);                        \
216                 flags = _raw_spin_lock_irqsave_nested(lock, subclass);  \
217         } while (0)
218 #else
219 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
220         do {                                                            \
221                 typecheck(unsigned long, flags);                        \
222                 flags = _raw_spin_lock_irqsave(lock);                   \
223         } while (0)
224 #endif
225 
226 #else
227 
228 #define raw_spin_lock_irqsave(lock, flags)              \
229         do {                                            \
230                 typecheck(unsigned long, flags);        \
231                 _raw_spin_lock_irqsave(lock, flags);    \
232         } while (0)
233 
234 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)     \
235         raw_spin_lock_irqsave(lock, flags)
236 
237 #endif
238 
239 #define raw_spin_lock_irq(lock)         _raw_spin_lock_irq(lock)
240 #define raw_spin_lock_bh(lock)          _raw_spin_lock_bh(lock)
241 #define raw_spin_unlock(lock)           _raw_spin_unlock(lock)
242 #define raw_spin_unlock_irq(lock)       _raw_spin_unlock_irq(lock)
243 
244 #define raw_spin_unlock_irqrestore(lock, flags)         \
245         do {                                                    \
246                 typecheck(unsigned long, flags);                \
247                 _raw_spin_unlock_irqrestore(lock, flags);       \
248         } while (0)
249 #define raw_spin_unlock_bh(lock)        _raw_spin_unlock_bh(lock)
250 
251 #define raw_spin_trylock_bh(lock) \
252         __cond_lock(lock, _raw_spin_trylock_bh(lock))
253 
254 #define raw_spin_trylock_irq(lock) \
255 ({ \
256         local_irq_disable(); \
257         raw_spin_trylock(lock) ? \
258         1 : ({ local_irq_enable(); 0;  }); \
259 })
260 
261 #define raw_spin_trylock_irqsave(lock, flags) \
262 ({ \
263         local_irq_save(flags); \
264         raw_spin_trylock(lock) ? \
265         1 : ({ local_irq_restore(flags); 0; }); \
266 })
267 
268 /**
269  * raw_spin_can_lock - would raw_spin_trylock() succeed?
270  * @lock: the spinlock in question.
271  */
272 #define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
273 
274 /* Include rwlock functions */
275 #include <linux/rwlock.h>
276 
277 /*
278  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
279  */
280 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
281 # include <linux/spinlock_api_smp.h>
282 #else
283 # include <linux/spinlock_api_up.h>
284 #endif
285 
286 /*
287  * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
288  */
289 
290 static inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
291 {
292         return &lock->rlock;
293 }
294 
295 #define spin_lock_init(_lock)                           \
296 do {                                                    \
297         spinlock_check(_lock);                          \
298         raw_spin_lock_init(&(_lock)->rlock);            \
299 } while (0)
300 
301 static inline void spin_lock(spinlock_t *lock)
302 {
303         raw_spin_lock(&lock->rlock);
304 }
305 
306 static inline void spin_lock_bh(spinlock_t *lock)
307 {
308         raw_spin_lock_bh(&lock->rlock);
309 }
310 
311 static inline int spin_trylock(spinlock_t *lock)
312 {
313         return raw_spin_trylock(&lock->rlock);
314 }
315 
316 #define spin_lock_nested(lock, subclass)                        \
317 do {                                                            \
318         raw_spin_lock_nested(spinlock_check(lock), subclass);   \
319 } while (0)
320 
321 #define spin_lock_nest_lock(lock, nest_lock)                            \
322 do {                                                                    \
323         raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
324 } while (0)
325 
326 static inline void spin_lock_irq(spinlock_t *lock)
327 {
328         raw_spin_lock_irq(&lock->rlock);
329 }
330 
331 #define spin_lock_irqsave(lock, flags)                          \
332 do {                                                            \
333         raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
334 } while (0)
335 
336 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
337 do {                                                                    \
338         raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
339 } while (0)
340 
341 static inline void spin_unlock(spinlock_t *lock)
342 {
343         raw_spin_unlock(&lock->rlock);
344 }
345 
346 static inline void spin_unlock_bh(spinlock_t *lock)
347 {
348         raw_spin_unlock_bh(&lock->rlock);
349 }
350 
351 static inline void spin_unlock_irq(spinlock_t *lock)
352 {
353         raw_spin_unlock_irq(&lock->rlock);
354 }
355 
356 static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
357 {
358         raw_spin_unlock_irqrestore(&lock->rlock, flags);
359 }
360 
361 static inline int spin_trylock_bh(spinlock_t *lock)
362 {
363         return raw_spin_trylock_bh(&lock->rlock);
364 }
365 
366 static inline int spin_trylock_irq(spinlock_t *lock)
367 {
368         return raw_spin_trylock_irq(&lock->rlock);
369 }
370 
371 #define spin_trylock_irqsave(lock, flags)                       \
372 ({                                                              \
373         raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
374 })
375 
376 static inline void spin_unlock_wait(spinlock_t *lock)
377 {
378         raw_spin_unlock_wait(&lock->rlock);
379 }
380 
381 static inline int spin_is_locked(spinlock_t *lock)
382 {
383         return raw_spin_is_locked(&lock->rlock);
384 }
385 
386 static inline int spin_is_contended(spinlock_t *lock)
387 {
388         return raw_spin_is_contended(&lock->rlock);
389 }
390 
391 static inline int spin_can_lock(spinlock_t *lock)
392 {
393         return raw_spin_can_lock(&lock->rlock);
394 }
395 
396 #define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
397 
398 /*
399  * Pull the atomic_t declaration:
400  * (asm-mips/atomic.h needs above definitions)
401  */
402 #include <linux/atomic.h>
403 /**
404  * atomic_dec_and_lock - lock on reaching reference count zero
405  * @atomic: the atomic counter
406  * @lock: the spinlock in question
407  *
408  * Decrements @atomic by 1.  If the result is 0, returns true and locks
409  * @lock.  Returns false for all other cases.
410  */
411 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
412 #define atomic_dec_and_lock(atomic, lock) \
413                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
414 
415 #endif /* __LINUX_SPINLOCK_H */
416 

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