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 <pzijlstr@redhat.com>
6 *
7 * see Documentation/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 #ifdef CONFIG_LOCKDEP
20
21 #include <linux/linkage.h>
22 #include <linux/list.h>
23 #include <linux/debug_locks.h>
24 #include <linux/stacktrace.h>
25
26 /*
27 * We'd rather not expose kernel/lockdep_states.h this wide, but we do need
28 * the total number of states... :-(
29 */
30 #define XXX_LOCK_USAGE_STATES (1+3*4)
31
32 #define MAX_LOCKDEP_SUBCLASSES 8UL
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 list_head 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[4];
134 unsigned long contending_point[4];
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 /*
161 * Every lock has a list of other locks that were taken after it.
162 * We only grow the list, never remove from it:
163 */
164 struct lock_list {
165 struct list_head entry;
166 struct lock_class *class;
167 struct stack_trace trace;
168 int distance;
169
170 /*
171 * The parent field is used to implement breadth-first search, and the
172 * bit 0 is reused to indicate if the lock has been accessed in BFS.
173 */
174 struct lock_list *parent;
175 };
176
177 /*
178 * We record lock dependency chains, so that we can cache them:
179 */
180 struct lock_chain {
181 u8 irq_context;
182 u8 depth;
183 u16 base;
184 struct list_head entry;
185 u64 chain_key;
186 };
187
188 #define MAX_LOCKDEP_KEYS_BITS 13
189 /*
190 * Subtract one because we offset hlock->class_idx by 1 in order
191 * to make 0 mean no class. This avoids overflowing the class_idx
192 * bitfield and hitting the BUG in hlock_class().
193 */
194 #define MAX_LOCKDEP_KEYS ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
195
196 struct held_lock {
197 /*
198 * One-way hash of the dependency chain up to this point. We
199 * hash the hashes step by step as the dependency chain grows.
200 *
201 * We use it for dependency-caching and we skip detection
202 * passes and dependency-updates if there is a cache-hit, so
203 * it is absolutely critical for 100% coverage of the validator
204 * to have a unique key value for every unique dependency path
205 * that can occur in the system, to make a unique hash value
206 * as likely as possible - hence the 64-bit width.
207 *
208 * The task struct holds the current hash value (initialized
209 * with zero), here we store the previous hash value:
210 */
211 u64 prev_chain_key;
212 unsigned long acquire_ip;
213 struct lockdep_map *instance;
214 struct lockdep_map *nest_lock;
215 #ifdef CONFIG_LOCK_STAT
216 u64 waittime_stamp;
217 u64 holdtime_stamp;
218 #endif
219 unsigned int class_idx:MAX_LOCKDEP_KEYS_BITS;
220 /*
221 * The lock-stack is unified in that the lock chains of interrupt
222 * contexts nest ontop of process context chains, but we 'separate'
223 * the hashes by starting with 0 if we cross into an interrupt
224 * context, and we also keep do not add cross-context lock
225 * dependencies - the lock usage graph walking covers that area
226 * anyway, and we'd just unnecessarily increase the number of
227 * dependencies otherwise. [Note: hardirq and softirq contexts
228 * are separated from each other too.]
229 *
230 * The following field is used to detect when we cross into an
231 * interrupt context:
232 */
233 unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
234 unsigned int trylock:1; /* 16 bits */
235
236 unsigned int read:2; /* see lock_acquire() comment */
237 unsigned int check:2; /* see lock_acquire() comment */
238 unsigned int hardirqs_off:1;
239 unsigned int references:11; /* 32 bits */
240 };
241
242 /*
243 * Initialization, self-test and debugging-output methods:
244 */
245 extern void lockdep_init(void);
246 extern void lockdep_info(void);
247 extern void lockdep_reset(void);
248 extern void lockdep_reset_lock(struct lockdep_map *lock);
249 extern void lockdep_free_key_range(void *start, unsigned long size);
250 extern void lockdep_sys_exit(void);
251
252 extern void lockdep_off(void);
253 extern void lockdep_on(void);
254
255 /*
256 * These methods are used by specific locking variants (spinlocks,
257 * rwlocks, mutexes and rwsems) to pass init/acquire/release events
258 * to lockdep:
259 */
260
261 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
262 struct lock_class_key *key, int subclass);
263
264 /*
265 * To initialize a lockdep_map statically use this macro.
266 * Note that _name must not be NULL.
267 */
268 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
269 { .name = (_name), .key = (void *)(_key), }
270
271 /*
272 * Reinitialize a lock key - for cases where there is special locking or
273 * special initialization of locks so that the validator gets the scope
274 * of dependencies wrong: they are either too broad (they need a class-split)
275 * or they are too narrow (they suffer from a false class-split):
276 */
277 #define lockdep_set_class(lock, key) \
278 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
279 #define lockdep_set_class_and_name(lock, key, name) \
280 lockdep_init_map(&(lock)->dep_map, name, key, 0)
281 #define lockdep_set_class_and_subclass(lock, key, sub) \
282 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
283 #define lockdep_set_subclass(lock, sub) \
284 lockdep_init_map(&(lock)->dep_map, #lock, \
285 (lock)->dep_map.key, sub)
286
287 #define lockdep_set_novalidate_class(lock) \
288 lockdep_set_class(lock, &__lockdep_no_validate__)
289 /*
290 * Compare locking classes
291 */
292 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
293
lockdep_match_key(struct lockdep_map * lock,struct lock_class_key * key)294 static inline int lockdep_match_key(struct lockdep_map *lock,
295 struct lock_class_key *key)
296 {
297 return lock->key == key;
298 }
299
300 /*
301 * Acquire a lock.
302 *
303 * Values for "read":
304 *
305 * 0: exclusive (write) acquire
306 * 1: read-acquire (no recursion allowed)
307 * 2: read-acquire with same-instance recursion allowed
308 *
309 * Values for check:
310 *
311 * 0: disabled
312 * 1: simple checks (freeing, held-at-exit-time, etc.)
313 * 2: full validation
314 */
315 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
316 int trylock, int read, int check,
317 struct lockdep_map *nest_lock, unsigned long ip);
318
319 extern void lock_release(struct lockdep_map *lock, int nested,
320 unsigned long ip);
321
322 #define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
323
324 extern int lock_is_held(struct lockdep_map *lock);
325
326 extern void lock_set_class(struct lockdep_map *lock, const char *name,
327 struct lock_class_key *key, unsigned int subclass,
328 unsigned long ip);
329
lock_set_subclass(struct lockdep_map * lock,unsigned int subclass,unsigned long ip)330 static inline void lock_set_subclass(struct lockdep_map *lock,
331 unsigned int subclass, unsigned long ip)
332 {
333 lock_set_class(lock, lock->name, lock->key, subclass, ip);
334 }
335
336 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
337 extern void lockdep_clear_current_reclaim_state(void);
338 extern void lockdep_trace_alloc(gfp_t mask);
339
340 # define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
341
342 #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
343
344 #define lockdep_assert_held(l) WARN_ON(debug_locks && !lockdep_is_held(l))
345
346 #else /* !LOCKDEP */
347
lockdep_off(void)348 static inline void lockdep_off(void)
349 {
350 }
351
lockdep_on(void)352 static inline void lockdep_on(void)
353 {
354 }
355
356 # define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
357 # define lock_release(l, n, i) do { } while (0)
358 # define lock_set_class(l, n, k, s, i) do { } while (0)
359 # define lock_set_subclass(l, s, i) do { } while (0)
360 # define lockdep_set_current_reclaim_state(g) do { } while (0)
361 # define lockdep_clear_current_reclaim_state() do { } while (0)
362 # define lockdep_trace_alloc(g) do { } while (0)
363 # define lockdep_init() do { } while (0)
364 # define lockdep_info() do { } while (0)
365 # define lockdep_init_map(lock, name, key, sub) \
366 do { (void)(name); (void)(key); } while (0)
367 # define lockdep_set_class(lock, key) do { (void)(key); } while (0)
368 # define lockdep_set_class_and_name(lock, key, name) \
369 do { (void)(key); (void)(name); } while (0)
370 #define lockdep_set_class_and_subclass(lock, key, sub) \
371 do { (void)(key); } while (0)
372 #define lockdep_set_subclass(lock, sub) do { } while (0)
373
374 #define lockdep_set_novalidate_class(lock) do { } while (0)
375
376 /*
377 * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
378 * case since the result is not well defined and the caller should rather
379 * #ifdef the call himself.
380 */
381
382 # define INIT_LOCKDEP
383 # define lockdep_reset() do { debug_locks = 1; } while (0)
384 # define lockdep_free_key_range(start, size) do { } while (0)
385 # define lockdep_sys_exit() do { } while (0)
386 /*
387 * The class key takes no space if lockdep is disabled:
388 */
389 struct lock_class_key { };
390
391 #define lockdep_depth(tsk) (0)
392
393 #define lockdep_assert_held(l) do { } while (0)
394
395 #endif /* !LOCKDEP */
396
397 #ifdef CONFIG_LOCK_STAT
398
399 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
400 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
401
402 #define LOCK_CONTENDED(_lock, try, lock) \
403 do { \
404 if (!try(_lock)) { \
405 lock_contended(&(_lock)->dep_map, _RET_IP_); \
406 lock(_lock); \
407 } \
408 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
409 } while (0)
410
411 #else /* CONFIG_LOCK_STAT */
412
413 #define lock_contended(lockdep_map, ip) do {} while (0)
414 #define lock_acquired(lockdep_map, ip) do {} while (0)
415
416 #define LOCK_CONTENDED(_lock, try, lock) \
417 lock(_lock)
418
419 #endif /* CONFIG_LOCK_STAT */
420
421 #ifdef CONFIG_LOCKDEP
422
423 /*
424 * On lockdep we dont want the hand-coded irq-enable of
425 * _raw_*_lock_flags() code, because lockdep assumes
426 * that interrupts are not re-enabled during lock-acquire:
427 */
428 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
429 LOCK_CONTENDED((_lock), (try), (lock))
430
431 #else /* CONFIG_LOCKDEP */
432
433 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
434 lockfl((_lock), (flags))
435
436 #endif /* CONFIG_LOCKDEP */
437
438 #ifdef CONFIG_TRACE_IRQFLAGS
439 extern void print_irqtrace_events(struct task_struct *curr);
440 #else
print_irqtrace_events(struct task_struct * curr)441 static inline void print_irqtrace_events(struct task_struct *curr)
442 {
443 }
444 #endif
445
446 /*
447 * For trivial one-depth nesting of a lock-class, the following
448 * global define can be used. (Subsystems with multiple levels
449 * of nesting should define their own lock-nesting subclasses.)
450 */
451 #define SINGLE_DEPTH_NESTING 1
452
453 /*
454 * Map the dependency ops to NOP or to real lockdep ops, depending
455 * on the per lock-class debug mode:
456 */
457
458 #ifdef CONFIG_DEBUG_LOCK_ALLOC
459 # ifdef CONFIG_PROVE_LOCKING
460 # define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
461 # define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
462 # else
463 # define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
464 # define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, NULL, i)
465 # endif
466 # define spin_release(l, n, i) lock_release(l, n, i)
467 #else
468 # define spin_acquire(l, s, t, i) do { } while (0)
469 # define spin_release(l, n, i) do { } while (0)
470 #endif
471
472 #ifdef CONFIG_DEBUG_LOCK_ALLOC
473 # ifdef CONFIG_PROVE_LOCKING
474 # define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
475 # define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, NULL, i)
476 # else
477 # define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
478 # define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, NULL, i)
479 # endif
480 # define rwlock_release(l, n, i) lock_release(l, n, i)
481 #else
482 # define rwlock_acquire(l, s, t, i) do { } while (0)
483 # define rwlock_acquire_read(l, s, t, i) do { } while (0)
484 # define rwlock_release(l, n, i) do { } while (0)
485 #endif
486
487 #ifdef CONFIG_DEBUG_LOCK_ALLOC
488 # ifdef CONFIG_PROVE_LOCKING
489 # define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
490 # else
491 # define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
492 # endif
493 # define mutex_release(l, n, i) lock_release(l, n, i)
494 #else
495 # define mutex_acquire(l, s, t, i) do { } while (0)
496 # define mutex_release(l, n, i) do { } while (0)
497 #endif
498
499 #ifdef CONFIG_DEBUG_LOCK_ALLOC
500 # ifdef CONFIG_PROVE_LOCKING
501 # define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
502 # define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, NULL, i)
503 # else
504 # define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
505 # define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, NULL, i)
506 # endif
507 # define rwsem_release(l, n, i) lock_release(l, n, i)
508 #else
509 # define rwsem_acquire(l, s, t, i) do { } while (0)
510 # define rwsem_acquire_read(l, s, t, i) do { } while (0)
511 # define rwsem_release(l, n, i) do { } while (0)
512 #endif
513
514 #ifdef CONFIG_DEBUG_LOCK_ALLOC
515 # ifdef CONFIG_PROVE_LOCKING
516 # define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
517 # define lock_map_acquire_read(l) lock_acquire(l, 0, 0, 2, 2, NULL, _THIS_IP_)
518 # else
519 # define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
520 # define lock_map_acquire_read(l) lock_acquire(l, 0, 0, 2, 1, NULL, _THIS_IP_)
521 # endif
522 # define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
523 #else
524 # define lock_map_acquire(l) do { } while (0)
525 # define lock_map_acquire_read(l) do { } while (0)
526 # define lock_map_release(l) do { } while (0)
527 #endif
528
529 #ifdef CONFIG_PROVE_LOCKING
530 # define might_lock(lock) \
531 do { \
532 typecheck(struct lockdep_map *, &(lock)->dep_map); \
533 lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_); \
534 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
535 } while (0)
536 # define might_lock_read(lock) \
537 do { \
538 typecheck(struct lockdep_map *, &(lock)->dep_map); \
539 lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_); \
540 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
541 } while (0)
542 #else
543 # define might_lock(lock) do { } while (0)
544 # define might_lock_read(lock) do { } while (0)
545 #endif
546
547 #ifdef CONFIG_PROVE_RCU
548 extern void lockdep_rcu_dereference(const char *file, const int line);
549 #endif
550
551 #endif /* __LINUX_LOCKDEP_H */
552