1 /*
2 * Runtime locking correctness validator
3 *
4 * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
5 * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
6 *
7 * see Documentation/locking/lockdep-design.txt for more details.
8 */
9 #ifndef __LINUX_LOCKDEP_H
10 #define __LINUX_LOCKDEP_H
11
12 struct task_struct;
13 struct lockdep_map;
14
15 /* for sysctl */
16 extern int prove_locking;
17 extern int lock_stat;
18
19 #define MAX_LOCKDEP_SUBCLASSES 8UL
20
21 #ifdef CONFIG_LOCKDEP
22
23 #include <linux/linkage.h>
24 #include <linux/list.h>
25 #include <linux/debug_locks.h>
26 #include <linux/stacktrace.h>
27
28 /*
29 * We'd rather not expose kernel/lockdep_states.h this wide, but we do need
30 * the total number of states... :-(
31 */
32 #define XXX_LOCK_USAGE_STATES (1+3*4)
33
34 /*
35 * NR_LOCKDEP_CACHING_CLASSES ... Number of classes
36 * cached in the instance of lockdep_map
37 *
38 * Currently main class (subclass == 0) and signle depth subclass
39 * are cached in lockdep_map. This optimization is mainly targeting
40 * on rq->lock. double_rq_lock() acquires this highly competitive with
41 * single depth.
42 */
43 #define NR_LOCKDEP_CACHING_CLASSES 2
44
45 /*
46 * Lock-classes are keyed via unique addresses, by embedding the
47 * lockclass-key into the kernel (or module) .data section. (For
48 * static locks we use the lock address itself as the key.)
49 */
50 struct lockdep_subclass_key {
51 char __one_byte;
52 } __attribute__ ((__packed__));
53
54 struct lock_class_key {
55 struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
56 };
57
58 extern struct lock_class_key __lockdep_no_validate__;
59
60 #define LOCKSTAT_POINTS 4
61
62 /*
63 * The lock-class itself:
64 */
65 struct lock_class {
66 /*
67 * class-hash:
68 */
69 struct hlist_node hash_entry;
70
71 /*
72 * global list of all lock-classes:
73 */
74 struct list_head lock_entry;
75
76 struct lockdep_subclass_key *key;
77 unsigned int subclass;
78 unsigned int dep_gen_id;
79
80 /*
81 * IRQ/softirq usage tracking bits:
82 */
83 unsigned long usage_mask;
84 struct stack_trace usage_traces[XXX_LOCK_USAGE_STATES];
85
86 /*
87 * These fields represent a directed graph of lock dependencies,
88 * to every node we attach a list of "forward" and a list of
89 * "backward" graph nodes.
90 */
91 struct list_head locks_after, locks_before;
92
93 /*
94 * Generation counter, when doing certain classes of graph walking,
95 * to ensure that we check one node only once:
96 */
97 unsigned int version;
98
99 /*
100 * Statistics counter:
101 */
102 unsigned long ops;
103
104 const char *name;
105 int name_version;
106
107 #ifdef CONFIG_LOCK_STAT
108 unsigned long contention_point[LOCKSTAT_POINTS];
109 unsigned long contending_point[LOCKSTAT_POINTS];
110 #endif
111 };
112
113 #ifdef CONFIG_LOCK_STAT
114 struct lock_time {
115 s64 min;
116 s64 max;
117 s64 total;
118 unsigned long nr;
119 };
120
121 enum bounce_type {
122 bounce_acquired_write,
123 bounce_acquired_read,
124 bounce_contended_write,
125 bounce_contended_read,
126 nr_bounce_types,
127
128 bounce_acquired = bounce_acquired_write,
129 bounce_contended = bounce_contended_write,
130 };
131
132 struct lock_class_stats {
133 unsigned long contention_point[LOCKSTAT_POINTS];
134 unsigned long contending_point[LOCKSTAT_POINTS];
135 struct lock_time read_waittime;
136 struct lock_time write_waittime;
137 struct lock_time read_holdtime;
138 struct lock_time write_holdtime;
139 unsigned long bounces[nr_bounce_types];
140 };
141
142 struct lock_class_stats lock_stats(struct lock_class *class);
143 void clear_lock_stats(struct lock_class *class);
144 #endif
145
146 /*
147 * Map the lock object (the lock instance) to the lock-class object.
148 * This is embedded into specific lock instances:
149 */
150 struct lockdep_map {
151 struct lock_class_key *key;
152 struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES];
153 const char *name;
154 #ifdef CONFIG_LOCK_STAT
155 int cpu;
156 unsigned long ip;
157 #endif
158 };
159
160 static inline void lockdep_copy_map(struct lockdep_map *to,
161 struct lockdep_map *from)
162 {
163 int i;
164
165 *to = *from;
166 /*
167 * Since the class cache can be modified concurrently we could observe
168 * half pointers (64bit arch using 32bit copy insns). Therefore clear
169 * the caches and take the performance hit.
170 *
171 * XXX it doesn't work well with lockdep_set_class_and_subclass(), since
172 * that relies on cache abuse.
173 */
174 for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
175 to->class_cache[i] = NULL;
176 }
177
178 /*
179 * Every lock has a list of other locks that were taken after it.
180 * We only grow the list, never remove from it:
181 */
182 struct lock_list {
183 struct list_head entry;
184 struct lock_class *class;
185 struct stack_trace trace;
186 int distance;
187
188 /*
189 * The parent field is used to implement breadth-first search, and the
190 * bit 0 is reused to indicate if the lock has been accessed in BFS.
191 */
192 struct lock_list *parent;
193 };
194
195 /*
196 * We record lock dependency chains, so that we can cache them:
197 */
198 struct lock_chain {
199 /* see BUILD_BUG_ON()s in lookup_chain_cache() */
200 unsigned int irq_context : 2,
201 depth : 6,
202 base : 24;
203 /* 4 byte hole */
204 struct hlist_node entry;
205 u64 chain_key;
206 };
207
208 #define MAX_LOCKDEP_KEYS_BITS 13
209 /*
210 * Subtract one because we offset hlock->class_idx by 1 in order
211 * to make 0 mean no class. This avoids overflowing the class_idx
212 * bitfield and hitting the BUG in hlock_class().
213 */
214 #define MAX_LOCKDEP_KEYS ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
215
216 struct held_lock {
217 /*
218 * One-way hash of the dependency chain up to this point. We
219 * hash the hashes step by step as the dependency chain grows.
220 *
221 * We use it for dependency-caching and we skip detection
222 * passes and dependency-updates if there is a cache-hit, so
223 * it is absolutely critical for 100% coverage of the validator
224 * to have a unique key value for every unique dependency path
225 * that can occur in the system, to make a unique hash value
226 * as likely as possible - hence the 64-bit width.
227 *
228 * The task struct holds the current hash value (initialized
229 * with zero), here we store the previous hash value:
230 */
231 u64 prev_chain_key;
232 unsigned long acquire_ip;
233 struct lockdep_map *instance;
234 struct lockdep_map *nest_lock;
235 #ifdef CONFIG_LOCK_STAT
236 u64 waittime_stamp;
237 u64 holdtime_stamp;
238 #endif
239 unsigned int class_idx:MAX_LOCKDEP_KEYS_BITS;
240 /*
241 * The lock-stack is unified in that the lock chains of interrupt
242 * contexts nest ontop of process context chains, but we 'separate'
243 * the hashes by starting with 0 if we cross into an interrupt
244 * context, and we also keep do not add cross-context lock
245 * dependencies - the lock usage graph walking covers that area
246 * anyway, and we'd just unnecessarily increase the number of
247 * dependencies otherwise. [Note: hardirq and softirq contexts
248 * are separated from each other too.]
249 *
250 * The following field is used to detect when we cross into an
251 * interrupt context:
252 */
253 unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
254 unsigned int trylock:1; /* 16 bits */
255
256 unsigned int read:2; /* see lock_acquire() comment */
257 unsigned int check:1; /* see lock_acquire() comment */
258 unsigned int hardirqs_off:1;
259 unsigned int references:12; /* 32 bits */
260 unsigned int pin_count;
261 };
262
263 /*
264 * Initialization, self-test and debugging-output methods:
265 */
266 extern void lockdep_info(void);
267 extern void lockdep_reset(void);
268 extern void lockdep_reset_lock(struct lockdep_map *lock);
269 extern void lockdep_free_key_range(void *start, unsigned long size);
270 extern asmlinkage void lockdep_sys_exit(void);
271
272 extern void lockdep_off(void);
273 extern void lockdep_on(void);
274
275 /*
276 * These methods are used by specific locking variants (spinlocks,
277 * rwlocks, mutexes and rwsems) to pass init/acquire/release events
278 * to lockdep:
279 */
280
281 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
282 struct lock_class_key *key, int subclass);
283
284 /*
285 * To initialize a lockdep_map statically use this macro.
286 * Note that _name must not be NULL.
287 */
288 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
289 { .name = (_name), .key = (void *)(_key), }
290
291 /*
292 * Reinitialize a lock key - for cases where there is special locking or
293 * special initialization of locks so that the validator gets the scope
294 * of dependencies wrong: they are either too broad (they need a class-split)
295 * or they are too narrow (they suffer from a false class-split):
296 */
297 #define lockdep_set_class(lock, key) \
298 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
299 #define lockdep_set_class_and_name(lock, key, name) \
300 lockdep_init_map(&(lock)->dep_map, name, key, 0)
301 #define lockdep_set_class_and_subclass(lock, key, sub) \
302 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
303 #define lockdep_set_subclass(lock, sub) \
304 lockdep_init_map(&(lock)->dep_map, #lock, \
305 (lock)->dep_map.key, sub)
306
307 #define lockdep_set_novalidate_class(lock) \
308 lockdep_set_class_and_name(lock, &__lockdep_no_validate__, #lock)
309 /*
310 * Compare locking classes
311 */
312 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
313
314 static inline int lockdep_match_key(struct lockdep_map *lock,
315 struct lock_class_key *key)
316 {
317 return lock->key == key;
318 }
319
320 /*
321 * Acquire a lock.
322 *
323 * Values for "read":
324 *
325 * 0: exclusive (write) acquire
326 * 1: read-acquire (no recursion allowed)
327 * 2: read-acquire with same-instance recursion allowed
328 *
329 * Values for check:
330 *
331 * 0: simple checks (freeing, held-at-exit-time, etc.)
332 * 1: full validation
333 */
334 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
335 int trylock, int read, int check,
336 struct lockdep_map *nest_lock, unsigned long ip);
337
338 extern void lock_release(struct lockdep_map *lock, int nested,
339 unsigned long ip);
340
341 /*
342 * Same "read" as for lock_acquire(), except -1 means any.
343 */
344 extern int lock_is_held_type(struct lockdep_map *lock, int read);
345
346 static inline int lock_is_held(struct lockdep_map *lock)
347 {
348 return lock_is_held_type(lock, -1);
349 }
350
351 #define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
352 #define lockdep_is_held_type(lock, r) lock_is_held_type(&(lock)->dep_map, (r))
353
354 extern void lock_set_class(struct lockdep_map *lock, const char *name,
355 struct lock_class_key *key, unsigned int subclass,
356 unsigned long ip);
357
358 static inline void lock_set_subclass(struct lockdep_map *lock,
359 unsigned int subclass, unsigned long ip)
360 {
361 lock_set_class(lock, lock->name, lock->key, subclass, ip);
362 }
363
364 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
365 extern void lockdep_clear_current_reclaim_state(void);
366 extern void lockdep_trace_alloc(gfp_t mask);
367
368 struct pin_cookie { unsigned int val; };
369
370 #define NIL_COOKIE (struct pin_cookie){ .val = 0U, }
371
372 extern struct pin_cookie lock_pin_lock(struct lockdep_map *lock);
373 extern void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie);
374 extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
375
376 # define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
377
378 #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
379
380 #define lockdep_assert_held(l) do { \
381 WARN_ON(debug_locks && !lockdep_is_held(l)); \
382 } while (0)
383
384 #define lockdep_assert_held_exclusive(l) do { \
385 WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
386 } while (0)
387
388 #define lockdep_assert_held_read(l) do { \
389 WARN_ON(debug_locks && !lockdep_is_held_type(l, 1)); \
390 } while (0)
391
392 #define lockdep_assert_held_once(l) do { \
393 WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
394 } while (0)
395
396 #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
397
398 #define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map)
399 #define lockdep_repin_lock(l,c) lock_repin_lock(&(l)->dep_map, (c))
400 #define lockdep_unpin_lock(l,c) lock_unpin_lock(&(l)->dep_map, (c))
401
402 #else /* !CONFIG_LOCKDEP */
403
404 static inline void lockdep_off(void)
405 {
406 }
407
408 static inline void lockdep_on(void)
409 {
410 }
411
412 # define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
413 # define lock_release(l, n, i) do { } while (0)
414 # define lock_set_class(l, n, k, s, i) do { } while (0)
415 # define lock_set_subclass(l, s, i) do { } while (0)
416 # define lockdep_set_current_reclaim_state(g) do { } while (0)
417 # define lockdep_clear_current_reclaim_state() do { } while (0)
418 # define lockdep_trace_alloc(g) do { } while (0)
419 # define lockdep_info() do { } while (0)
420 # define lockdep_init_map(lock, name, key, sub) \
421 do { (void)(name); (void)(key); } while (0)
422 # define lockdep_set_class(lock, key) do { (void)(key); } while (0)
423 # define lockdep_set_class_and_name(lock, key, name) \
424 do { (void)(key); (void)(name); } while (0)
425 #define lockdep_set_class_and_subclass(lock, key, sub) \
426 do { (void)(key); } while (0)
427 #define lockdep_set_subclass(lock, sub) do { } while (0)
428
429 #define lockdep_set_novalidate_class(lock) do { } while (0)
430
431 /*
432 * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
433 * case since the result is not well defined and the caller should rather
434 * #ifdef the call himself.
435 */
436
437 # define INIT_LOCKDEP
438 # define lockdep_reset() do { debug_locks = 1; } while (0)
439 # define lockdep_free_key_range(start, size) do { } while (0)
440 # define lockdep_sys_exit() do { } while (0)
441 /*
442 * The class key takes no space if lockdep is disabled:
443 */
444 struct lock_class_key { };
445
446 #define lockdep_depth(tsk) (0)
447
448 #define lockdep_is_held_type(l, r) (1)
449
450 #define lockdep_assert_held(l) do { (void)(l); } while (0)
451 #define lockdep_assert_held_exclusive(l) do { (void)(l); } while (0)
452 #define lockdep_assert_held_read(l) do { (void)(l); } while (0)
453 #define lockdep_assert_held_once(l) do { (void)(l); } while (0)
454
455 #define lockdep_recursing(tsk) (0)
456
457 struct pin_cookie { };
458
459 #define NIL_COOKIE (struct pin_cookie){ }
460
461 #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; })
462 #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0)
463 #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0)
464
465 #endif /* !LOCKDEP */
466
467 #ifdef CONFIG_LOCK_STAT
468
469 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
470 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
471
472 #define LOCK_CONTENDED(_lock, try, lock) \
473 do { \
474 if (!try(_lock)) { \
475 lock_contended(&(_lock)->dep_map, _RET_IP_); \
476 lock(_lock); \
477 } \
478 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
479 } while (0)
480
481 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
482 ({ \
483 int ____err = 0; \
484 if (!try(_lock)) { \
485 lock_contended(&(_lock)->dep_map, _RET_IP_); \
486 ____err = lock(_lock); \
487 } \
488 if (!____err) \
489 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
490 ____err; \
491 })
492
493 #else /* CONFIG_LOCK_STAT */
494
495 #define lock_contended(lockdep_map, ip) do {} while (0)
496 #define lock_acquired(lockdep_map, ip) do {} while (0)
497
498 #define LOCK_CONTENDED(_lock, try, lock) \
499 lock(_lock)
500
501 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
502 lock(_lock)
503
504 #endif /* CONFIG_LOCK_STAT */
505
506 #ifdef CONFIG_LOCKDEP
507
508 /*
509 * On lockdep we dont want the hand-coded irq-enable of
510 * _raw_*_lock_flags() code, because lockdep assumes
511 * that interrupts are not re-enabled during lock-acquire:
512 */
513 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
514 LOCK_CONTENDED((_lock), (try), (lock))
515
516 #else /* CONFIG_LOCKDEP */
517
518 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
519 lockfl((_lock), (flags))
520
521 #endif /* CONFIG_LOCKDEP */
522
523 #ifdef CONFIG_TRACE_IRQFLAGS
524 extern void print_irqtrace_events(struct task_struct *curr);
525 #else
526 static inline void print_irqtrace_events(struct task_struct *curr)
527 {
528 }
529 #endif
530
531 /*
532 * For trivial one-depth nesting of a lock-class, the following
533 * global define can be used. (Subsystems with multiple levels
534 * of nesting should define their own lock-nesting subclasses.)
535 */
536 #define SINGLE_DEPTH_NESTING 1
537
538 /*
539 * Map the dependency ops to NOP or to real lockdep ops, depending
540 * on the per lock-class debug mode:
541 */
542
543 #define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
544 #define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
545 #define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)
546
547 #define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
548 #define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
549 #define spin_release(l, n, i) lock_release(l, n, i)
550
551 #define rwlock_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
552 #define rwlock_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
553 #define rwlock_release(l, n, i) lock_release(l, n, i)
554
555 #define seqcount_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
556 #define seqcount_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
557 #define seqcount_release(l, n, i) lock_release(l, n, i)
558
559 #define mutex_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
560 #define mutex_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
561 #define mutex_release(l, n, i) lock_release(l, n, i)
562
563 #define rwsem_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
564 #define rwsem_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
565 #define rwsem_acquire_read(l, s, t, i) lock_acquire_shared(l, s, t, NULL, i)
566 #define rwsem_release(l, n, i) lock_release(l, n, i)
567
568 #define lock_map_acquire(l) lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
569 #define lock_map_acquire_read(l) lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
570 #define lock_map_acquire_tryread(l) lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
571 #define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
572
573 #ifdef CONFIG_PROVE_LOCKING
574 # define might_lock(lock) \
575 do { \
576 typecheck(struct lockdep_map *, &(lock)->dep_map); \
577 lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_); \
578 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
579 } while (0)
580 # define might_lock_read(lock) \
581 do { \
582 typecheck(struct lockdep_map *, &(lock)->dep_map); \
583 lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_); \
584 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
585 } while (0)
586 #else
587 # define might_lock(lock) do { } while (0)
588 # define might_lock_read(lock) do { } while (0)
589 #endif
590
591 #ifdef CONFIG_LOCKDEP
592 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
593 #else
594 static inline void
595 lockdep_rcu_suspicious(const char *file, const int line, const char *s)
596 {
597 }
598 #endif
599
600 #endif /* __LINUX_LOCKDEP_H */
601
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