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 <asm/barrier.h>
65 : #include <asm/mmiowb.h>
66 :
67 :
68 : /*
69 : * Must define these before including other files, inline functions need them
70 : */
71 : #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
72 :
73 : #define LOCK_SECTION_START(extra) \
74 : ".subsection 1\n\t" \
75 : extra \
76 : ".ifndef " LOCK_SECTION_NAME "\n\t" \
77 : LOCK_SECTION_NAME ":\n\t" \
78 : ".endif\n"
79 :
80 : #define LOCK_SECTION_END \
81 : ".previous\n\t"
82 :
83 : #define __lockfunc __section(".spinlock.text")
84 :
85 : /*
86 : * Pull the arch_spinlock_t and arch_rwlock_t definitions:
87 : */
88 : #include <linux/spinlock_types.h>
89 :
90 : /*
91 : * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
92 : */
93 : #ifdef CONFIG_SMP
94 : # include <asm/spinlock.h>
95 : #else
96 : # include <linux/spinlock_up.h>
97 : #endif
98 :
99 : #ifdef CONFIG_DEBUG_SPINLOCK
100 : extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
101 : struct lock_class_key *key, short inner);
102 :
103 : # define raw_spin_lock_init(lock) \
104 : do { \
105 : static struct lock_class_key __key; \
106 : \
107 : __raw_spin_lock_init((lock), #lock, &__key, LD_WAIT_SPIN); \
108 : } while (0)
109 :
110 : #else
111 : # define raw_spin_lock_init(lock) \
112 : do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
113 : #endif
114 :
115 : #define raw_spin_is_locked(lock) arch_spin_is_locked(&(lock)->raw_lock)
116 :
117 : #ifdef arch_spin_is_contended
118 : #define raw_spin_is_contended(lock) arch_spin_is_contended(&(lock)->raw_lock)
119 : #else
120 : #define raw_spin_is_contended(lock) (((void)(lock), 0))
121 : #endif /*arch_spin_is_contended*/
122 :
123 : /*
124 : * smp_mb__after_spinlock() provides the equivalent of a full memory barrier
125 : * between program-order earlier lock acquisitions and program-order later
126 : * memory accesses.
127 : *
128 : * This guarantees that the following two properties hold:
129 : *
130 : * 1) Given the snippet:
131 : *
132 : * { X = 0; Y = 0; }
133 : *
134 : * CPU0 CPU1
135 : *
136 : * WRITE_ONCE(X, 1); WRITE_ONCE(Y, 1);
137 : * spin_lock(S); smp_mb();
138 : * smp_mb__after_spinlock(); r1 = READ_ONCE(X);
139 : * r0 = READ_ONCE(Y);
140 : * spin_unlock(S);
141 : *
142 : * it is forbidden that CPU0 does not observe CPU1's store to Y (r0 = 0)
143 : * and CPU1 does not observe CPU0's store to X (r1 = 0); see the comments
144 : * preceding the call to smp_mb__after_spinlock() in __schedule() and in
145 : * try_to_wake_up().
146 : *
147 : * 2) Given the snippet:
148 : *
149 : * { X = 0; Y = 0; }
150 : *
151 : * CPU0 CPU1 CPU2
152 : *
153 : * spin_lock(S); spin_lock(S); r1 = READ_ONCE(Y);
154 : * WRITE_ONCE(X, 1); smp_mb__after_spinlock(); smp_rmb();
155 : * spin_unlock(S); r0 = READ_ONCE(X); r2 = READ_ONCE(X);
156 : * WRITE_ONCE(Y, 1);
157 : * spin_unlock(S);
158 : *
159 : * it is forbidden that CPU0's critical section executes before CPU1's
160 : * critical section (r0 = 1), CPU2 observes CPU1's store to Y (r1 = 1)
161 : * and CPU2 does not observe CPU0's store to X (r2 = 0); see the comments
162 : * preceding the calls to smp_rmb() in try_to_wake_up() for similar
163 : * snippets but "projected" onto two CPUs.
164 : *
165 : * Property (2) upgrades the lock to an RCsc lock.
166 : *
167 : * Since most load-store architectures implement ACQUIRE with an smp_mb() after
168 : * the LL/SC loop, they need no further barriers. Similarly all our TSO
169 : * architectures imply an smp_mb() for each atomic instruction and equally don't
170 : * need more.
171 : *
172 : * Architectures that can implement ACQUIRE better need to take care.
173 : */
174 : #ifndef smp_mb__after_spinlock
175 : #define smp_mb__after_spinlock() kcsan_mb()
176 : #endif
177 :
178 : #ifdef CONFIG_DEBUG_SPINLOCK
179 : extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
180 : extern int do_raw_spin_trylock(raw_spinlock_t *lock);
181 : extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
182 : #else
183 : static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
184 : {
185 : __acquire(lock);
186 : arch_spin_lock(&lock->raw_lock);
187 : mmiowb_spin_lock();
188 : }
189 :
190 : static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
191 : {
192 : int ret = arch_spin_trylock(&(lock)->raw_lock);
193 :
194 : if (ret)
195 : mmiowb_spin_lock();
196 :
197 : return ret;
198 : }
199 :
200 : static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
201 : {
202 : mmiowb_spin_unlock();
203 : arch_spin_unlock(&lock->raw_lock);
204 : __release(lock);
205 : }
206 : #endif
207 :
208 : /*
209 : * Define the various spin_lock methods. Note we define these
210 : * regardless of whether CONFIG_SMP or CONFIG_PREEMPTION are set. The
211 : * various methods are defined as nops in the case they are not
212 : * required.
213 : */
214 : #define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
215 :
216 : #define raw_spin_lock(lock) _raw_spin_lock(lock)
217 :
218 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
219 : # define raw_spin_lock_nested(lock, subclass) \
220 : _raw_spin_lock_nested(lock, subclass)
221 :
222 : # define raw_spin_lock_nest_lock(lock, nest_lock) \
223 : do { \
224 : typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
225 : _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
226 : } while (0)
227 : #else
228 : /*
229 : * Always evaluate the 'subclass' argument to avoid that the compiler
230 : * warns about set-but-not-used variables when building with
231 : * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
232 : */
233 : # define raw_spin_lock_nested(lock, subclass) \
234 : _raw_spin_lock(((void)(subclass), (lock)))
235 : # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
236 : #endif
237 :
238 : #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
239 :
240 : #define raw_spin_lock_irqsave(lock, flags) \
241 : do { \
242 : typecheck(unsigned long, flags); \
243 : flags = _raw_spin_lock_irqsave(lock); \
244 : } while (0)
245 :
246 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
247 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
248 : do { \
249 : typecheck(unsigned long, flags); \
250 : flags = _raw_spin_lock_irqsave_nested(lock, subclass); \
251 : } while (0)
252 : #else
253 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
254 : do { \
255 : typecheck(unsigned long, flags); \
256 : flags = _raw_spin_lock_irqsave(lock); \
257 : } while (0)
258 : #endif
259 :
260 : #else
261 :
262 : #define raw_spin_lock_irqsave(lock, flags) \
263 : do { \
264 : typecheck(unsigned long, flags); \
265 : _raw_spin_lock_irqsave(lock, flags); \
266 : } while (0)
267 :
268 : #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
269 : raw_spin_lock_irqsave(lock, flags)
270 :
271 : #endif
272 :
273 : #define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock)
274 : #define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock)
275 : #define raw_spin_unlock(lock) _raw_spin_unlock(lock)
276 : #define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock)
277 :
278 : #define raw_spin_unlock_irqrestore(lock, flags) \
279 : do { \
280 : typecheck(unsigned long, flags); \
281 : _raw_spin_unlock_irqrestore(lock, flags); \
282 : } while (0)
283 : #define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock)
284 :
285 : #define raw_spin_trylock_bh(lock) \
286 : __cond_lock(lock, _raw_spin_trylock_bh(lock))
287 :
288 : #define raw_spin_trylock_irq(lock) \
289 : ({ \
290 : local_irq_disable(); \
291 : raw_spin_trylock(lock) ? \
292 : 1 : ({ local_irq_enable(); 0; }); \
293 : })
294 :
295 : #define raw_spin_trylock_irqsave(lock, flags) \
296 : ({ \
297 : local_irq_save(flags); \
298 : raw_spin_trylock(lock) ? \
299 : 1 : ({ local_irq_restore(flags); 0; }); \
300 : })
301 :
302 : #ifndef CONFIG_PREEMPT_RT
303 : /* Include rwlock functions for !RT */
304 : #include <linux/rwlock.h>
305 : #endif
306 :
307 : /*
308 : * Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
309 : */
310 : #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
311 : # include <linux/spinlock_api_smp.h>
312 : #else
313 : # include <linux/spinlock_api_up.h>
314 : #endif
315 :
316 : /* Non PREEMPT_RT kernel, map to raw spinlocks: */
317 : #ifndef CONFIG_PREEMPT_RT
318 :
319 : /*
320 : * Map the spin_lock functions to the raw variants for PREEMPT_RT=n
321 : */
322 :
323 : static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
324 : {
325 : return &lock->rlock;
326 : }
327 :
328 : #ifdef CONFIG_DEBUG_SPINLOCK
329 :
330 : # define spin_lock_init(lock) \
331 : do { \
332 : static struct lock_class_key __key; \
333 : \
334 : __raw_spin_lock_init(spinlock_check(lock), \
335 : #lock, &__key, LD_WAIT_CONFIG); \
336 : } while (0)
337 :
338 : #else
339 :
340 : # define spin_lock_init(_lock) \
341 : do { \
342 : spinlock_check(_lock); \
343 : *(_lock) = __SPIN_LOCK_UNLOCKED(_lock); \
344 : } while (0)
345 :
346 : #endif
347 :
348 : static __always_inline void spin_lock(spinlock_t *lock)
349 : {
350 23242 : raw_spin_lock(&lock->rlock);
351 : }
352 :
353 : static __always_inline void spin_lock_bh(spinlock_t *lock)
354 : {
355 0 : raw_spin_lock_bh(&lock->rlock);
356 : }
357 :
358 : static __always_inline int spin_trylock(spinlock_t *lock)
359 : {
360 47076 : return raw_spin_trylock(&lock->rlock);
361 : }
362 :
363 : #define spin_lock_nested(lock, subclass) \
364 : do { \
365 : raw_spin_lock_nested(spinlock_check(lock), subclass); \
366 : } while (0)
367 :
368 : #define spin_lock_nest_lock(lock, nest_lock) \
369 : do { \
370 : raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \
371 : } while (0)
372 :
373 : static __always_inline void spin_lock_irq(spinlock_t *lock)
374 : {
375 3369 : raw_spin_lock_irq(&lock->rlock);
376 : }
377 :
378 : #define spin_lock_irqsave(lock, flags) \
379 : do { \
380 : raw_spin_lock_irqsave(spinlock_check(lock), flags); \
381 : } while (0)
382 :
383 : #define spin_lock_irqsave_nested(lock, flags, subclass) \
384 : do { \
385 : raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
386 : } while (0)
387 :
388 : static __always_inline void spin_unlock(spinlock_t *lock)
389 : {
390 70318 : raw_spin_unlock(&lock->rlock);
391 : }
392 :
393 : static __always_inline void spin_unlock_bh(spinlock_t *lock)
394 : {
395 0 : raw_spin_unlock_bh(&lock->rlock);
396 : }
397 :
398 : static __always_inline void spin_unlock_irq(spinlock_t *lock)
399 : {
400 3369 : raw_spin_unlock_irq(&lock->rlock);
401 : }
402 :
403 : static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
404 : {
405 10981 : raw_spin_unlock_irqrestore(&lock->rlock, flags);
406 : }
407 :
408 : static __always_inline int spin_trylock_bh(spinlock_t *lock)
409 : {
410 : return raw_spin_trylock_bh(&lock->rlock);
411 : }
412 :
413 : static __always_inline int spin_trylock_irq(spinlock_t *lock)
414 : {
415 : return raw_spin_trylock_irq(&lock->rlock);
416 : }
417 :
418 : #define spin_trylock_irqsave(lock, flags) \
419 : ({ \
420 : raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
421 : })
422 :
423 : /**
424 : * spin_is_locked() - Check whether a spinlock is locked.
425 : * @lock: Pointer to the spinlock.
426 : *
427 : * This function is NOT required to provide any memory ordering
428 : * guarantees; it could be used for debugging purposes or, when
429 : * additional synchronization is needed, accompanied with other
430 : * constructs (memory barriers) enforcing the synchronization.
431 : *
432 : * Returns: 1 if @lock is locked, 0 otherwise.
433 : *
434 : * Note that the function only tells you that the spinlock is
435 : * seen to be locked, not that it is locked on your CPU.
436 : *
437 : * Further, on CONFIG_SMP=n builds with CONFIG_DEBUG_SPINLOCK=n,
438 : * the return value is always 0 (see include/linux/spinlock_up.h).
439 : * Therefore you should not rely heavily on the return value.
440 : */
441 : static __always_inline int spin_is_locked(spinlock_t *lock)
442 : {
443 : return raw_spin_is_locked(&lock->rlock);
444 : }
445 :
446 : static __always_inline int spin_is_contended(spinlock_t *lock)
447 : {
448 : return raw_spin_is_contended(&lock->rlock);
449 : }
450 :
451 : #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)
452 :
453 : #else /* !CONFIG_PREEMPT_RT */
454 : # include <linux/spinlock_rt.h>
455 : #endif /* CONFIG_PREEMPT_RT */
456 :
457 : /*
458 : * Pull the atomic_t declaration:
459 : * (asm-mips/atomic.h needs above definitions)
460 : */
461 : #include <linux/atomic.h>
462 : /**
463 : * atomic_dec_and_lock - lock on reaching reference count zero
464 : * @atomic: the atomic counter
465 : * @lock: the spinlock in question
466 : *
467 : * Decrements @atomic by 1. If the result is 0, returns true and locks
468 : * @lock. Returns false for all other cases.
469 : */
470 : extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
471 : #define atomic_dec_and_lock(atomic, lock) \
472 : __cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
473 :
474 : extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
475 : unsigned long *flags);
476 : #define atomic_dec_and_lock_irqsave(atomic, lock, flags) \
477 : __cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags)))
478 :
479 : extern int _atomic_dec_and_raw_lock(atomic_t *atomic, raw_spinlock_t *lock);
480 : #define atomic_dec_and_raw_lock(atomic, lock) \
481 : __cond_lock(lock, _atomic_dec_and_raw_lock(atomic, lock))
482 :
483 : extern int _atomic_dec_and_raw_lock_irqsave(atomic_t *atomic, raw_spinlock_t *lock,
484 : unsigned long *flags);
485 : #define atomic_dec_and_raw_lock_irqsave(atomic, lock, flags) \
486 : __cond_lock(lock, _atomic_dec_and_raw_lock_irqsave(atomic, lock, &(flags)))
487 :
488 : int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask,
489 : size_t max_size, unsigned int cpu_mult,
490 : gfp_t gfp, const char *name,
491 : struct lock_class_key *key);
492 :
493 : #define alloc_bucket_spinlocks(locks, lock_mask, max_size, cpu_mult, gfp) \
494 : ({ \
495 : static struct lock_class_key key; \
496 : int ret; \
497 : \
498 : ret = __alloc_bucket_spinlocks(locks, lock_mask, max_size, \
499 : cpu_mult, gfp, #locks, &key); \
500 : ret; \
501 : })
502 :
503 : void free_bucket_spinlocks(spinlock_t *locks);
504 :
505 : #undef __LINUX_INSIDE_SPINLOCK_H
506 : #endif /* __LINUX_SPINLOCK_H */
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