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