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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 LOADs and STOREs 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  * raw_spin_unlock_wait - wait until the spinlock gets unlocked
135  * @lock: the spinlock in question.
136  */
137 #define raw_spin_unlock_wait(lock)      arch_spin_unlock_wait(&(lock)->raw_lock)
138 
139 #ifdef CONFIG_DEBUG_SPINLOCK
140  extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
141 #define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
142  extern int do_raw_spin_trylock(raw_spinlock_t *lock);
143  extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
144 #else
145 static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
146 {
147         __acquire(lock);
148         arch_spin_lock(&lock->raw_lock);
149 }
150 
151 static inline void
152 do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
153 {
154         __acquire(lock);
155         arch_spin_lock_flags(&lock->raw_lock, *flags);
156 }
157 
158 static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
159 {
160         return arch_spin_trylock(&(lock)->raw_lock);
161 }
162 
163 static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
164 {
165         arch_spin_unlock(&lock->raw_lock);
166         __release(lock);
167 }
168 #endif
169 
170 /*
171  * Define the various spin_lock methods.  Note we define these
172  * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
173  * various methods are defined as nops in the case they are not
174  * required.
175  */
176 #define raw_spin_trylock(lock)  __cond_lock(lock, _raw_spin_trylock(lock))
177 
178 #define raw_spin_lock(lock)     _raw_spin_lock(lock)
179 
180 #ifdef CONFIG_DEBUG_LOCK_ALLOC
181 # define raw_spin_lock_nested(lock, subclass) \
182         _raw_spin_lock_nested(lock, subclass)
183 # define raw_spin_lock_bh_nested(lock, subclass) \
184         _raw_spin_lock_bh_nested(lock, subclass)
185 
186 # define raw_spin_lock_nest_lock(lock, nest_lock)                       \
187          do {                                                           \
188                  typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
189                  _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
190          } while (0)
191 #else
192 /*
193  * Always evaluate the 'subclass' argument to avoid that the compiler
194  * warns about set-but-not-used variables when building with
195  * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
196  */
197 # define raw_spin_lock_nested(lock, subclass)           \
198         _raw_spin_lock(((void)(subclass), (lock)))
199 # define raw_spin_lock_nest_lock(lock, nest_lock)       _raw_spin_lock(lock)
200 # define raw_spin_lock_bh_nested(lock, subclass)        _raw_spin_lock_bh(lock)
201 #endif
202 
203 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
204 
205 #define raw_spin_lock_irqsave(lock, flags)                      \
206         do {                                            \
207                 typecheck(unsigned long, flags);        \
208                 flags = _raw_spin_lock_irqsave(lock);   \
209         } while (0)
210 
211 #ifdef CONFIG_DEBUG_LOCK_ALLOC
212 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
213         do {                                                            \
214                 typecheck(unsigned long, flags);                        \
215                 flags = _raw_spin_lock_irqsave_nested(lock, subclass);  \
216         } while (0)
217 #else
218 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)             \
219         do {                                                            \
220                 typecheck(unsigned long, flags);                        \
221                 flags = _raw_spin_lock_irqsave(lock);                   \
222         } while (0)
223 #endif
224 
225 #else
226 
227 #define raw_spin_lock_irqsave(lock, flags)              \
228         do {                                            \
229                 typecheck(unsigned long, flags);        \
230                 _raw_spin_lock_irqsave(lock, flags);    \
231         } while (0)
232 
233 #define raw_spin_lock_irqsave_nested(lock, flags, subclass)     \
234         raw_spin_lock_irqsave(lock, flags)
235 
236 #endif
237 
238 #define raw_spin_lock_irq(lock)         _raw_spin_lock_irq(lock)
239 #define raw_spin_lock_bh(lock)          _raw_spin_lock_bh(lock)
240 #define raw_spin_unlock(lock)           _raw_spin_unlock(lock)
241 #define raw_spin_unlock_irq(lock)       _raw_spin_unlock_irq(lock)
242 
243 #define raw_spin_unlock_irqrestore(lock, flags)         \
244         do {                                                    \
245                 typecheck(unsigned long, flags);                \
246                 _raw_spin_unlock_irqrestore(lock, flags);       \
247         } while (0)
248 #define raw_spin_unlock_bh(lock)        _raw_spin_unlock_bh(lock)
249 
250 #define raw_spin_trylock_bh(lock) \
251         __cond_lock(lock, _raw_spin_trylock_bh(lock))
252 
253 #define raw_spin_trylock_irq(lock) \
254 ({ \
255         local_irq_disable(); \
256         raw_spin_trylock(lock) ? \
257         1 : ({ local_irq_enable(); 0;  }); \
258 })
259 
260 #define raw_spin_trylock_irqsave(lock, flags) \
261 ({ \
262         local_irq_save(flags); \
263         raw_spin_trylock(lock) ? \
264         1 : ({ local_irq_restore(flags); 0; }); \
265 })
266 
267 /**
268  * raw_spin_can_lock - would raw_spin_trylock() succeed?
269  * @lock: the spinlock in question.
270  */
271 #define raw_spin_can_lock(lock) (!raw_spin_is_locked(lock))
272 
273 /* Include rwlock functions */
274 #include <linux/rwlock.h>
275 
276 /*
277  * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
278  */
279 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
280 # include <linux/spinlock_api_smp.h>
281 #else
282 # include <linux/spinlock_api_up.h>
283 #endif
284 
285 /*
286  * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
287  */
288 
289 static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
290 {
291         return &lock->rlock;
292 }
293 
294 #define spin_lock_init(_lock)                           \
295 do {                                                    \
296         spinlock_check(_lock);                          \
297         raw_spin_lock_init(&(_lock)->rlock);            \
298 } while (0)
299 
300 static __always_inline void spin_lock(spinlock_t *lock)
301 {
302         raw_spin_lock(&lock->rlock);
303 }
304 
305 static __always_inline void spin_lock_bh(spinlock_t *lock)
306 {
307         raw_spin_lock_bh(&lock->rlock);
308 }
309 
310 static __always_inline int spin_trylock(spinlock_t *lock)
311 {
312         return raw_spin_trylock(&lock->rlock);
313 }
314 
315 #define spin_lock_nested(lock, subclass)                        \
316 do {                                                            \
317         raw_spin_lock_nested(spinlock_check(lock), subclass);   \
318 } while (0)
319 
320 #define spin_lock_bh_nested(lock, subclass)                     \
321 do {                                                            \
322         raw_spin_lock_bh_nested(spinlock_check(lock), subclass);\
323 } while (0)
324 
325 #define spin_lock_nest_lock(lock, nest_lock)                            \
326 do {                                                                    \
327         raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock);       \
328 } while (0)
329 
330 static __always_inline void spin_lock_irq(spinlock_t *lock)
331 {
332         raw_spin_lock_irq(&lock->rlock);
333 }
334 
335 #define spin_lock_irqsave(lock, flags)                          \
336 do {                                                            \
337         raw_spin_lock_irqsave(spinlock_check(lock), flags);     \
338 } while (0)
339 
340 #define spin_lock_irqsave_nested(lock, flags, subclass)                 \
341 do {                                                                    \
342         raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
343 } while (0)
344 
345 static __always_inline void spin_unlock(spinlock_t *lock)
346 {
347         raw_spin_unlock(&lock->rlock);
348 }
349 
350 static __always_inline void spin_unlock_bh(spinlock_t *lock)
351 {
352         raw_spin_unlock_bh(&lock->rlock);
353 }
354 
355 static __always_inline void spin_unlock_irq(spinlock_t *lock)
356 {
357         raw_spin_unlock_irq(&lock->rlock);
358 }
359 
360 static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
361 {
362         raw_spin_unlock_irqrestore(&lock->rlock, flags);
363 }
364 
365 static __always_inline int spin_trylock_bh(spinlock_t *lock)
366 {
367         return raw_spin_trylock_bh(&lock->rlock);
368 }
369 
370 static __always_inline int spin_trylock_irq(spinlock_t *lock)
371 {
372         return raw_spin_trylock_irq(&lock->rlock);
373 }
374 
375 #define spin_trylock_irqsave(lock, flags)                       \
376 ({                                                              \
377         raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
378 })
379 
380 static __always_inline void spin_unlock_wait(spinlock_t *lock)
381 {
382         raw_spin_unlock_wait(&lock->rlock);
383 }
384 
385 static __always_inline int spin_is_locked(spinlock_t *lock)
386 {
387         return raw_spin_is_locked(&lock->rlock);
388 }
389 
390 static __always_inline int spin_is_contended(spinlock_t *lock)
391 {
392         return raw_spin_is_contended(&lock->rlock);
393 }
394 
395 static __always_inline int spin_can_lock(spinlock_t *lock)
396 {
397         return raw_spin_can_lock(&lock->rlock);
398 }
399 
400 #define assert_spin_locked(lock)        assert_raw_spin_locked(&(lock)->rlock)
401 
402 /*
403  * Pull the atomic_t declaration:
404  * (asm-mips/atomic.h needs above definitions)
405  */
406 #include <linux/atomic.h>
407 /**
408  * atomic_dec_and_lock - lock on reaching reference count zero
409  * @atomic: the atomic counter
410  * @lock: the spinlock in question
411  *
412  * Decrements @atomic by 1.  If the result is 0, returns true and locks
413  * @lock.  Returns false for all other cases.
414  */
415 extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
416 #define atomic_dec_and_lock(atomic, lock) \
417                 __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
418 
419 #endif /* __LINUX_SPINLOCK_H */
420 

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