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
lockdep_copy_map(struct lockdep_map * to,struct lockdep_map * from)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
lockdep_match_key(struct lockdep_map * lock,struct lock_class_key * key)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 #define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
342
343 extern int lock_is_held(struct lockdep_map *lock);
344
345 extern void lock_set_class(struct lockdep_map *lock, const char *name,
346 struct lock_class_key *key, unsigned int subclass,
347 unsigned long ip);
348
lock_set_subclass(struct lockdep_map * lock,unsigned int subclass,unsigned long ip)349 static inline void lock_set_subclass(struct lockdep_map *lock,
350 unsigned int subclass, unsigned long ip)
351 {
352 lock_set_class(lock, lock->name, lock->key, subclass, ip);
353 }
354
355 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
356 extern void lockdep_clear_current_reclaim_state(void);
357 extern void lockdep_trace_alloc(gfp_t mask);
358
359 struct pin_cookie { unsigned int val; };
360
361 #define NIL_COOKIE (struct pin_cookie){ .val = 0U, }
362
363 extern struct pin_cookie lock_pin_lock(struct lockdep_map *lock);
364 extern void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie);
365 extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
366
367 # define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
368
369 #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
370
371 #define lockdep_assert_held(l) do { \
372 WARN_ON(debug_locks && !lockdep_is_held(l)); \
373 } while (0)
374
375 #define lockdep_assert_held_once(l) do { \
376 WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
377 } while (0)
378
379 #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
380
381 #define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map)
382 #define lockdep_repin_lock(l,c) lock_repin_lock(&(l)->dep_map, (c))
383 #define lockdep_unpin_lock(l,c) lock_unpin_lock(&(l)->dep_map, (c))
384
385 #else /* !CONFIG_LOCKDEP */
386
lockdep_off(void)387 static inline void lockdep_off(void)
388 {
389 }
390
lockdep_on(void)391 static inline void lockdep_on(void)
392 {
393 }
394
395 # define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
396 # define lock_release(l, n, i) do { } while (0)
397 # define lock_set_class(l, n, k, s, i) do { } while (0)
398 # define lock_set_subclass(l, s, i) do { } while (0)
399 # define lockdep_set_current_reclaim_state(g) do { } while (0)
400 # define lockdep_clear_current_reclaim_state() do { } while (0)
401 # define lockdep_trace_alloc(g) do { } while (0)
402 # define lockdep_info() do { } while (0)
403 # define lockdep_init_map(lock, name, key, sub) \
404 do { (void)(name); (void)(key); } while (0)
405 # define lockdep_set_class(lock, key) do { (void)(key); } while (0)
406 # define lockdep_set_class_and_name(lock, key, name) \
407 do { (void)(key); (void)(name); } while (0)
408 #define lockdep_set_class_and_subclass(lock, key, sub) \
409 do { (void)(key); } while (0)
410 #define lockdep_set_subclass(lock, sub) do { } while (0)
411
412 #define lockdep_set_novalidate_class(lock) do { } while (0)
413
414 /*
415 * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
416 * case since the result is not well defined and the caller should rather
417 * #ifdef the call himself.
418 */
419
420 # define INIT_LOCKDEP
421 # define lockdep_reset() do { debug_locks = 1; } while (0)
422 # define lockdep_free_key_range(start, size) do { } while (0)
423 # define lockdep_sys_exit() do { } while (0)
424 /*
425 * The class key takes no space if lockdep is disabled:
426 */
427 struct lock_class_key { };
428
429 #define lockdep_depth(tsk) (0)
430
431 #define lockdep_assert_held(l) do { (void)(l); } while (0)
432 #define lockdep_assert_held_once(l) do { (void)(l); } while (0)
433
434 #define lockdep_recursing(tsk) (0)
435
436 struct pin_cookie { };
437
438 #define NIL_COOKIE (struct pin_cookie){ }
439
440 #define lockdep_pin_lock(l) ({ struct pin_cookie cookie; cookie; })
441 #define lockdep_repin_lock(l, c) do { (void)(l); (void)(c); } while (0)
442 #define lockdep_unpin_lock(l, c) do { (void)(l); (void)(c); } while (0)
443
444 #endif /* !LOCKDEP */
445
446 #ifdef CONFIG_LOCK_STAT
447
448 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
449 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
450
451 #define LOCK_CONTENDED(_lock, try, lock) \
452 do { \
453 if (!try(_lock)) { \
454 lock_contended(&(_lock)->dep_map, _RET_IP_); \
455 lock(_lock); \
456 } \
457 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
458 } while (0)
459
460 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
461 ({ \
462 int ____err = 0; \
463 if (!try(_lock)) { \
464 lock_contended(&(_lock)->dep_map, _RET_IP_); \
465 ____err = lock(_lock); \
466 } \
467 if (!____err) \
468 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
469 ____err; \
470 })
471
472 #else /* CONFIG_LOCK_STAT */
473
474 #define lock_contended(lockdep_map, ip) do {} while (0)
475 #define lock_acquired(lockdep_map, ip) do {} while (0)
476
477 #define LOCK_CONTENDED(_lock, try, lock) \
478 lock(_lock)
479
480 #define LOCK_CONTENDED_RETURN(_lock, try, lock) \
481 lock(_lock)
482
483 #endif /* CONFIG_LOCK_STAT */
484
485 #ifdef CONFIG_LOCKDEP
486
487 /*
488 * On lockdep we dont want the hand-coded irq-enable of
489 * _raw_*_lock_flags() code, because lockdep assumes
490 * that interrupts are not re-enabled during lock-acquire:
491 */
492 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
493 LOCK_CONTENDED((_lock), (try), (lock))
494
495 #else /* CONFIG_LOCKDEP */
496
497 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
498 lockfl((_lock), (flags))
499
500 #endif /* CONFIG_LOCKDEP */
501
502 #ifdef CONFIG_TRACE_IRQFLAGS
503 extern void print_irqtrace_events(struct task_struct *curr);
504 #else
print_irqtrace_events(struct task_struct * curr)505 static inline void print_irqtrace_events(struct task_struct *curr)
506 {
507 }
508 #endif
509
510 /*
511 * For trivial one-depth nesting of a lock-class, the following
512 * global define can be used. (Subsystems with multiple levels
513 * of nesting should define their own lock-nesting subclasses.)
514 */
515 #define SINGLE_DEPTH_NESTING 1
516
517 /*
518 * Map the dependency ops to NOP or to real lockdep ops, depending
519 * on the per lock-class debug mode:
520 */
521
522 #define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
523 #define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
524 #define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)
525
526 #define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
527 #define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
528 #define spin_release(l, n, i) lock_release(l, n, i)
529
530 #define rwlock_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
531 #define rwlock_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
532 #define rwlock_release(l, n, i) lock_release(l, n, i)
533
534 #define seqcount_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
535 #define seqcount_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
536 #define seqcount_release(l, n, i) lock_release(l, n, i)
537
538 #define mutex_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
539 #define mutex_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
540 #define mutex_release(l, n, i) lock_release(l, n, i)
541
542 #define rwsem_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
543 #define rwsem_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
544 #define rwsem_acquire_read(l, s, t, i) lock_acquire_shared(l, s, t, NULL, i)
545 #define rwsem_release(l, n, i) lock_release(l, n, i)
546
547 #define lock_map_acquire(l) lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
548 #define lock_map_acquire_read(l) lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
549 #define lock_map_acquire_tryread(l) lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
550 #define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
551
552 #ifdef CONFIG_PROVE_LOCKING
553 # define might_lock(lock) \
554 do { \
555 typecheck(struct lockdep_map *, &(lock)->dep_map); \
556 lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_); \
557 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
558 } while (0)
559 # define might_lock_read(lock) \
560 do { \
561 typecheck(struct lockdep_map *, &(lock)->dep_map); \
562 lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_); \
563 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
564 } while (0)
565 #else
566 # define might_lock(lock) do { } while (0)
567 # define might_lock_read(lock) do { } while (0)
568 #endif
569
570 #ifdef CONFIG_LOCKDEP
571 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
572 #else
573 static inline void
lockdep_rcu_suspicious(const char * file,const int line,const char * s)574 lockdep_rcu_suspicious(const char *file, const int line, const char *s)
575 {
576 }
577 #endif
578
579 #endif /* __LINUX_LOCKDEP_H */
580