Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef __LINUX_SPINLOCK_H
3 : #define __LINUX_SPINLOCK_H
4 : #define __LINUX_INSIDE_SPINLOCK_H
5 :
6 : /*
7 : * include/linux/spinlock.h - generic spinlock/rwlock declarations
8 : *
9 : * here's the role of the various spinlock/rwlock related include files:
10 : *
11 : * on SMP builds:
12 : *
13 : * asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
14 : * initializers
15 : *
16 : * linux/spinlock_types_raw:
17 : * The raw types and initializers
18 : * linux/spinlock_types.h:
19 : * defines the generic type and initializers
20 : *
21 : * asm/spinlock.h: contains the arch_spin_*()/etc. lowlevel
22 : * implementations, mostly inline assembly code
23 : *
24 : * (also included on UP-debug builds:)
25 : *
26 : * linux/spinlock_api_smp.h:
27 : * contains the prototypes for the _spin_*() APIs.
28 : *
29 : * linux/spinlock.h: builds the final spin_*() APIs.
30 : *
31 : * on UP builds:
32 : *
33 : * linux/spinlock_type_up.h:
34 : * contains the generic, simplified UP spinlock type.
35 : * (which is an empty structure on non-debug builds)
36 : *
37 : * linux/spinlock_types_raw:
38 : * The raw RT types and initializers
39 : * linux/spinlock_types.h:
40 : * defines the generic type and initializers
41 : *
42 : * linux/spinlock_up.h:
43 : * contains the arch_spin_*()/etc. version of UP
44 : * builds. (which are NOPs on non-debug, non-preempt
45 : * builds)
46 : *
47 : * (included on UP-non-debug builds:)
48 : *
49 : * linux/spinlock_api_up.h:
50 : * builds the _spin_*() APIs.
51 : *
52 : * linux/spinlock.h: builds the final spin_*() APIs.
53 : */
54 :
55 : #include <linux/typecheck.h>
56 : #include <linux/preempt.h>
57 : #include <linux/linkage.h>
58 : #include <linux/compiler.h>
59 : #include <linux/irqflags.h>
60 : #include <linux/thread_info.h>
61 : #include <linux/stringify.h>
62 : #include <linux/bottom_half.h>
63 : #include <linux/lockdep.h>
64 : #include <linux/cleanup.h>
65 : #include <asm/barrier.h>
66 : #include <asm/mmiowb.h>
67 :
68 :
69 : /*
70 : * Must define these before including other files, inline functions need them
71 : */
72 : #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
73 :
74 : #define LOCK_SECTION_START(extra) \
75 : ".subsection 1\n\t" \
76 : extra \
77 : ".ifndef " LOCK_SECTION_NAME "\n\t" \
78 : LOCK_SECTION_NAME ":\n\t" \
79 : ".endif\n"
80 :
81 : #define LOCK_SECTION_END \
82 : ".previous\n\t"
83 :
84 : #define __lockfunc __section(".spinlock.text")
85 :
86 : /*
87 : * Pull the arch_spinlock_t and arch_rwlock_t definitions:
88 : */
89 : #include <linux/spinlock_types.h>
90 :
91 : /*
92 : * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
93 : */
94 : #ifdef CONFIG_SMP
95 : # include <asm/spinlock.h>
96 : #else
97 : # include <linux/spinlock_up.h>
98 : #endif
99 :
100 : #ifdef CONFIG_DEBUG_SPINLOCK
101 : extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
102 : struct lock_class_key *key, short inner);
103 :
104 : # define raw_spin_lock_init(lock) \
105 : do { \
106 : static struct lock_class_key __key; \
107 : \
108 : __raw_spin_lock_init((lock), #lock, &__key, LD_WAIT_SPIN); \
109 : } while (0)
110 :
111 : #else
112 : # define raw_spin_lock_init(lock) \
113 : do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
114 : #endif
115 :
116 : #define raw_spin_is_locked(lock) arch_spin_is_locked(&(lock)->raw_lock)
117 :
118 : #ifdef arch_spin_is_contended
119 : #define raw_spin_is_contended(lock) arch_spin_is_contended(&(lock)->raw_lock)
120 : #else
121 : #define raw_spin_is_contended(lock) (((void)(lock), 0))
122 : #endif /*arch_spin_is_contended*/
123 :
124 : /*
125 : * smp_mb__after_spinlock() provides the equivalent of a full memory barrier
126 : * between program-order earlier lock acquisitions and program-order later
127 : * memory accesses.
128 : *
129 : * This guarantees that the following two properties hold:
130 : *
131 : * 1) Given the snippet:
132 : *
133 : * { X = 0; Y = 0; }
134 : *
135 : * CPU0 CPU1
136 : *
137 : * WRITE_ONCE(X, 1); WRITE_ONCE(Y, 1);
138 : * spin_lock(S); smp_mb();
139 : * smp_mb__after_spinlock(); r1 = READ_ONCE(X);
140 : * r0 = READ_ONCE(Y);
141 : * spin_unlock(S);
142 : *
143 : * it is forbidden that CPU0 does not observe CPU1's store to Y (r0 = 0)
144 : * and CPU1 does not observe CPU0's store to X (r1 = 0); see the comments
145 : * preceding the call to smp_mb__after_spinlock() in __schedule() and in
146 : * try_to_wake_up().
147 : *
148 : * 2) Given the snippet:
149 : *
150 : * { X = 0; Y = 0; }
151 : *
152 : * CPU0 CPU1 CPU2
153 : *
154 : * spin_lock(S); spin_lock(S); r1 = READ_ONCE(Y);
155 : * WRITE_ONCE(X, 1); smp_mb__after_spinlock(); smp_rmb();
156 : * spin_unlock(S); r0 = READ_ONCE(X); r2 = READ_ONCE(X);
157 : * WRITE_ONCE(Y, 1);
158 : * spin_unlock(S);
159 : *
160 : * it is forbidden that CPU0's critical section executes before CPU1's
161 : * critical section (r0 = 1), CPU2 observes CPU1's store to Y (r1 = 1)
162 : * and CPU2 does not observe CPU0's store to X (r2 = 0); see the comments
163 : * preceding the calls to smp_rmb() in try_to_wake_up() for similar
164 : * snippets but "projected" onto two CPUs.
165 : *
166 : * Property (2) upgrades the lock to an RCsc lock.
167 : *
168 : * Since most load-store architectures implement ACQUIRE with an smp_mb() after
169 : * the LL/SC loop, they need no further barriers. Similarly all our TSO
170 : * architectures imply an smp_mb() for each atomic instruction and equally don't
171 : * need more.
172 : *
173 : * Architectures that can implement ACQUIRE better need to take care.
174 : */
175 : #ifndef smp_mb__after_spinlock
176 : #define smp_mb__after_spinlock() kcsan_mb()
177 : #endif
178 :
179 : #ifdef CONFIG_DEBUG_SPINLOCK
180 : extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
181 : extern int do_raw_spin_trylock(raw_spinlock_t *lock);
182 : extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
183 : #else
184 : static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
185 : {
186 : __acquire(lock);
187 : arch_spin_lock(&lock->raw_lock);
188 : mmiowb_spin_lock();
189 : }
190 :
191 : static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
192 : {
193 : int ret = arch_spin_trylock(&(lock)->raw_lock);
194 :
195 : if (ret)
196 : mmiowb_spin_lock();
197 :
198 : return ret;
199 : }
200 :
201 : static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
202 : {
203 : mmiowb_spin_unlock();
204 : arch_spin_unlock(&lock->raw_lock);
205 : __release(lock);
206 : }
207 : #endif
208 :
209 : /*
210 : * Define the various spin_lock methods. Note we define these
211 : * regardless of whether CONFIG_SMP or CONFIG_PREEMPTION are set. The
212 : * various methods are defined as nops in the case they are not
213 : * required.
214 : */
215 : #define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
216 :
217 : #define raw_spin_lock(lock) _raw_spin_lock(lock)
218 :
219 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
220 : # define raw_spin_lock_nested(lock, subclass) \
221 : _raw_spin_lock_nested(lock, subclass)
222 :
223 : # define raw_spin_lock_nest_lock(lock, nest_lock) \
224 : do { \
225 : typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
226 : _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
227 : } while (0)
228 : #else
229 : /*
230 : * Always evaluate the 'subclass' argument to avoid that the compiler
231 : * warns about set-but-not-used variables when building with
232 : * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
233 : */
234 : # define raw_spin_lock_nested(lock, subclass) \
235 : _raw_spin_lock(((void)(subclass), (lock)))
236 : # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
237 : #endif
238 :
239 : #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
240 :
241 : #define raw_spin_lock_irqsave(lock, flags) \
242 : do { \
243 : typecheck(unsigned long, flags); \
244 : flags = _raw_spin_lock_irqsave(lock); \
245 : } while (0)
246 :
247 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
248 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
249 : do { \
250 : typecheck(unsigned long, flags); \
251 : flags = _raw_spin_lock_irqsave_nested(lock, subclass); \
252 : } while (0)
253 : #else
254 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
255 : do { \
256 : typecheck(unsigned long, flags); \
257 : flags = _raw_spin_lock_irqsave(lock); \
258 : } while (0)
259 : #endif
260 :
261 : #else
262 :
263 : #define raw_spin_lock_irqsave(lock, flags) \
264 : do { \
265 : typecheck(unsigned long, flags); \
266 : _raw_spin_lock_irqsave(lock, flags); \
267 : } while (0)
268 :
269 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
270 : raw_spin_lock_irqsave(lock, flags)
271 :
272 : #endif
273 :
274 : #define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock)
275 : #define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock)
276 : #define raw_spin_unlock(lock) _raw_spin_unlock(lock)
277 : #define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock)
278 :
279 : #define raw_spin_unlock_irqrestore(lock, flags) \
280 : do { \
281 : typecheck(unsigned long, flags); \
282 : _raw_spin_unlock_irqrestore(lock, flags); \
283 : } while (0)
284 : #define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock)
285 :
286 : #define raw_spin_trylock_bh(lock) \
287 : __cond_lock(lock, _raw_spin_trylock_bh(lock))
288 :
289 : #define raw_spin_trylock_irq(lock) \
290 : ({ \
291 : local_irq_disable(); \
292 : raw_spin_trylock(lock) ? \
293 : 1 : ({ local_irq_enable(); 0; }); \
294 : })
295 :
296 : #define raw_spin_trylock_irqsave(lock, flags) \
297 : ({ \
298 : local_irq_save(flags); \
299 : raw_spin_trylock(lock) ? \
300 : 1 : ({ local_irq_restore(flags); 0; }); \
301 : })
302 :
303 : #ifndef CONFIG_PREEMPT_RT
304 : /* Include rwlock functions for !RT */
305 : #include <linux/rwlock.h>
306 : #endif
307 :
308 : /*
309 : * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
310 : */
311 : #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
312 : # include <linux/spinlock_api_smp.h>
313 : #else
314 : # include <linux/spinlock_api_up.h>
315 : #endif
316 :
317 : /* Non PREEMPT_RT kernel, map to raw spinlocks: */
318 : #ifndef CONFIG_PREEMPT_RT
319 :
320 : /*
321 : * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
322 : */
323 :
324 : static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
325 : {
326 : return &lock->rlock;
327 : }
328 :
329 : #ifdef CONFIG_DEBUG_SPINLOCK
330 :
331 : # define spin_lock_init(lock) \
332 : do { \
333 : static struct lock_class_key __key; \
334 : \
335 : __raw_spin_lock_init(spinlock_check(lock), \
336 : #lock, &__key, LD_WAIT_CONFIG); \
337 : } while (0)
338 :
339 : #else
340 :
341 : # define spin_lock_init(_lock) \
342 : do { \
343 : spinlock_check(_lock); \
344 : *(_lock) = __SPIN_LOCK_UNLOCKED(_lock); \
345 : } while (0)
346 :
347 : #endif
348 :
349 : static __always_inline void spin_lock(spinlock_t *lock)
350 : {
351 17296 : raw_spin_lock(&lock->rlock);
352 : }
353 :
354 : static __always_inline void spin_lock_bh(spinlock_t *lock)
355 : {
356 0 : raw_spin_lock_bh(&lock->rlock);
357 : }
358 :
359 : static __always_inline int spin_trylock(spinlock_t *lock)
360 : {
361 462 : return raw_spin_trylock(&lock->rlock);
362 : }
363 :
364 : #define spin_lock_nested(lock, subclass) \
365 : do { \
366 : raw_spin_lock_nested(spinlock_check(lock), subclass); \
367 : } while (0)
368 :
369 : #define spin_lock_nest_lock(lock, nest_lock) \
370 : do { \
371 : raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \
372 : } while (0)
373 :
374 : static __always_inline void spin_lock_irq(spinlock_t *lock)
375 : {
376 1775 : raw_spin_lock_irq(&lock->rlock);
377 : }
378 :
379 : #define spin_lock_irqsave(lock, flags) \
380 : do { \
381 : raw_spin_lock_irqsave(spinlock_check(lock), flags); \
382 : } while (0)
383 :
384 : #define spin_lock_irqsave_nested(lock, flags, subclass) \
385 : do { \
386 : raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
387 : } while (0)
388 :
389 : static __always_inline void spin_unlock(spinlock_t *lock)
390 : {
391 17758 : raw_spin_unlock(&lock->rlock);
392 : }
393 :
394 : static __always_inline void spin_unlock_bh(spinlock_t *lock)
395 : {
396 0 : raw_spin_unlock_bh(&lock->rlock);
397 : }
398 :
399 : static __always_inline void spin_unlock_irq(spinlock_t *lock)
400 : {
401 1775 : raw_spin_unlock_irq(&lock->rlock);
402 : }
403 :
404 : static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
405 : {
406 4093 : raw_spin_unlock_irqrestore(&lock->rlock, flags);
407 : }
408 :
409 : static __always_inline int spin_trylock_bh(spinlock_t *lock)
410 : {
411 : return raw_spin_trylock_bh(&lock->rlock);
412 : }
413 :
414 : static __always_inline int spin_trylock_irq(spinlock_t *lock)
415 : {
416 : return raw_spin_trylock_irq(&lock->rlock);
417 : }
418 :
419 : #define spin_trylock_irqsave(lock, flags) \
420 : ({ \
421 : raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
422 : })
423 :
424 : /**
425 : * spin_is_locked() - Check whether a spinlock is locked.
426 : * @lock: Pointer to the spinlock.
427 : *
428 : * This function is NOT required to provide any memory ordering
429 : * guarantees; it could be used for debugging purposes or, when
430 : * additional synchronization is needed, accompanied with other
431 : * constructs (memory barriers) enforcing the synchronization.
432 : *
433 : * Returns: 1 if @lock is locked, 0 otherwise.
434 : *
435 : * Note that the function only tells you that the spinlock is
436 : * seen to be locked, not that it is locked on your CPU.
437 : *
438 : * Further, on CONFIG_SMP=n builds with CONFIG_DEBUG_SPINLOCK=n,
439 : * the return value is always 0 (see include/linux/spinlock_up.h).
440 : * Therefore you should not rely heavily on the return value.
441 : */
442 : static __always_inline int spin_is_locked(spinlock_t *lock)
443 : {
444 : return raw_spin_is_locked(&lock->rlock);
445 : }
446 :
447 : static __always_inline int spin_is_contended(spinlock_t *lock)
448 : {
449 : return raw_spin_is_contended(&lock->rlock);
450 : }
451 :
452 : #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)
453 :
454 : #else /* !CONFIG_PREEMPT_RT */
455 : # include <linux/spinlock_rt.h>
456 : #endif /* CONFIG_PREEMPT_RT */
457 :
458 : /*
459 : * Pull the atomic_t declaration:
460 : * (asm-mips/atomic.h needs above definitions)
461 : */
462 : #include <linux/atomic.h>
463 : /**
464 : * atomic_dec_and_lock - lock on reaching reference count zero
465 : * @atomic: the atomic counter
466 : * @lock: the spinlock in question
467 : *
468 : * Decrements @atomic by 1. If the result is 0, returns true and locks
469 : * @lock. Returns false for all other cases.
470 : */
471 : extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
472 : #define atomic_dec_and_lock(atomic, lock) \
473 : __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
474 :
475 : extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
476 : unsigned long *flags);
477 : #define atomic_dec_and_lock_irqsave(atomic, lock, flags) \
478 : __cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags)))
479 :
480 : extern int _atomic_dec_and_raw_lock(atomic_t *atomic, raw_spinlock_t *lock);
481 : #define atomic_dec_and_raw_lock(atomic, lock) \
482 : __cond_lock(lock, _atomic_dec_and_raw_lock(atomic, lock))
483 :
484 : extern int _atomic_dec_and_raw_lock_irqsave(atomic_t *atomic, raw_spinlock_t *lock,
485 : unsigned long *flags);
486 : #define atomic_dec_and_raw_lock_irqsave(atomic, lock, flags) \
487 : __cond_lock(lock, _atomic_dec_and_raw_lock_irqsave(atomic, lock, &(flags)))
488 :
489 : int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask,
490 : size_t max_size, unsigned int cpu_mult,
491 : gfp_t gfp, const char *name,
492 : struct lock_class_key *key);
493 :
494 : #define alloc_bucket_spinlocks(locks, lock_mask, max_size, cpu_mult, gfp) \
495 : ({ \
496 : static struct lock_class_key key; \
497 : int ret; \
498 : \
499 : ret = __alloc_bucket_spinlocks(locks, lock_mask, max_size, \
500 : cpu_mult, gfp, #locks, &key); \
501 : ret; \
502 : })
503 :
504 : void free_bucket_spinlocks(spinlock_t *locks);
505 :
506 : DEFINE_LOCK_GUARD_1(raw_spinlock, raw_spinlock_t,
507 : raw_spin_lock(_T->lock),
508 : raw_spin_unlock(_T->lock))
509 :
510 : DEFINE_LOCK_GUARD_1(raw_spinlock_nested, raw_spinlock_t,
511 : raw_spin_lock_nested(_T->lock, SINGLE_DEPTH_NESTING),
512 : raw_spin_unlock(_T->lock))
513 :
514 : DEFINE_LOCK_GUARD_1(raw_spinlock_irq, raw_spinlock_t,
515 : raw_spin_lock_irq(_T->lock),
516 : raw_spin_unlock_irq(_T->lock))
517 :
518 : DEFINE_LOCK_GUARD_1(raw_spinlock_irqsave, raw_spinlock_t,
519 : raw_spin_lock_irqsave(_T->lock, _T->flags),
520 : raw_spin_unlock_irqrestore(_T->lock, _T->flags),
521 : unsigned long flags)
522 :
523 : DEFINE_LOCK_GUARD_1(spinlock, spinlock_t,
524 : spin_lock(_T->lock),
525 : spin_unlock(_T->lock))
526 :
527 : DEFINE_LOCK_GUARD_1(spinlock_irq, spinlock_t,
528 : spin_lock_irq(_T->lock),
529 : spin_unlock_irq(_T->lock))
530 :
531 : DEFINE_LOCK_GUARD_1(spinlock_irqsave, spinlock_t,
532 : spin_lock_irqsave(_T->lock, _T->flags),
533 : spin_unlock_irqrestore(_T->lock, _T->flags),
534 : unsigned long flags)
535 :
536 : #undef __LINUX_INSIDE_SPINLOCK_H
537 : #endif /* __LINUX_SPINLOCK_H */
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