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 #ifdef CONFIG_LOCKDEP
16
17 #include <linux/linkage.h>
18 #include <linux/list.h>
19 #include <linux/debug_locks.h>
20 #include <linux/stacktrace.h>
21
22 /*
23 * Lock-class usage-state bits:
24 */
25 enum lock_usage_bit
26 {
27 LOCK_USED = 0,
28 LOCK_USED_IN_HARDIRQ,
29 LOCK_USED_IN_SOFTIRQ,
30 LOCK_ENABLED_SOFTIRQS,
31 LOCK_ENABLED_HARDIRQS,
32 LOCK_USED_IN_HARDIRQ_READ,
33 LOCK_USED_IN_SOFTIRQ_READ,
34 LOCK_ENABLED_SOFTIRQS_READ,
35 LOCK_ENABLED_HARDIRQS_READ,
36 LOCK_USAGE_STATES
37 };
38
39 /*
40 * Usage-state bitmasks:
41 */
42 #define LOCKF_USED (1 << LOCK_USED)
43 #define LOCKF_USED_IN_HARDIRQ (1 << LOCK_USED_IN_HARDIRQ)
44 #define LOCKF_USED_IN_SOFTIRQ (1 << LOCK_USED_IN_SOFTIRQ)
45 #define LOCKF_ENABLED_HARDIRQS (1 << LOCK_ENABLED_HARDIRQS)
46 #define LOCKF_ENABLED_SOFTIRQS (1 << LOCK_ENABLED_SOFTIRQS)
47
48 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
49 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
50
51 #define LOCKF_USED_IN_HARDIRQ_READ (1 << LOCK_USED_IN_HARDIRQ_READ)
52 #define LOCKF_USED_IN_SOFTIRQ_READ (1 << LOCK_USED_IN_SOFTIRQ_READ)
53 #define LOCKF_ENABLED_HARDIRQS_READ (1 << LOCK_ENABLED_HARDIRQS_READ)
54 #define LOCKF_ENABLED_SOFTIRQS_READ (1 << LOCK_ENABLED_SOFTIRQS_READ)
55
56 #define LOCKF_ENABLED_IRQS_READ \
57 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
58 #define LOCKF_USED_IN_IRQ_READ \
59 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
60
61 #define MAX_LOCKDEP_SUBCLASSES 8UL
62
63 /*
64 * Lock-classes are keyed via unique addresses, by embedding the
65 * lockclass-key into the kernel (or module) .data section. (For
66 * static locks we use the lock address itself as the key.)
67 */
68 struct lockdep_subclass_key {
69 char __one_byte;
70 } __attribute__ ((__packed__));
71
72 struct lock_class_key {
73 struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
74 };
75
76 #define LOCKSTAT_POINTS 4
77
78 /*
79 * The lock-class itself:
80 */
81 struct lock_class {
82 /*
83 * class-hash:
84 */
85 struct list_head hash_entry;
86
87 /*
88 * global list of all lock-classes:
89 */
90 struct list_head lock_entry;
91
92 struct lockdep_subclass_key *key;
93 unsigned int subclass;
94 unsigned int dep_gen_id;
95
96 /*
97 * IRQ/softirq usage tracking bits:
98 */
99 unsigned long usage_mask;
100 struct stack_trace usage_traces[LOCK_USAGE_STATES];
101
102 /*
103 * These fields represent a directed graph of lock dependencies,
104 * to every node we attach a list of "forward" and a list of
105 * "backward" graph nodes.
106 */
107 struct list_head locks_after, locks_before;
108
109 /*
110 * Generation counter, when doing certain classes of graph walking,
111 * to ensure that we check one node only once:
112 */
113 unsigned int version;
114
115 /*
116 * Statistics counter:
117 */
118 unsigned long ops;
119
120 const char *name;
121 int name_version;
122
123 #ifdef CONFIG_LOCK_STAT
124 unsigned long contention_point[LOCKSTAT_POINTS];
125 unsigned long contending_point[LOCKSTAT_POINTS];
126 #endif
127 };
128
129 #ifdef CONFIG_LOCK_STAT
130 struct lock_time {
131 s64 min;
132 s64 max;
133 s64 total;
134 unsigned long nr;
135 };
136
137 enum bounce_type {
138 bounce_acquired_write,
139 bounce_acquired_read,
140 bounce_contended_write,
141 bounce_contended_read,
142 nr_bounce_types,
143
144 bounce_acquired = bounce_acquired_write,
145 bounce_contended = bounce_contended_write,
146 };
147
148 struct lock_class_stats {
149 unsigned long contention_point[4];
150 unsigned long contending_point[4];
151 struct lock_time read_waittime;
152 struct lock_time write_waittime;
153 struct lock_time read_holdtime;
154 struct lock_time write_holdtime;
155 unsigned long bounces[nr_bounce_types];
156 };
157
158 struct lock_class_stats lock_stats(struct lock_class *class);
159 void clear_lock_stats(struct lock_class *class);
160 #endif
161
162 /*
163 * Map the lock object (the lock instance) to the lock-class object.
164 * This is embedded into specific lock instances:
165 */
166 struct lockdep_map {
167 struct lock_class_key *key;
168 struct lock_class *class_cache;
169 const char *name;
170 #ifdef CONFIG_LOCK_STAT
171 int cpu;
172 unsigned long ip;
173 #endif
174 };
175
176 /*
177 * Every lock has a list of other locks that were taken after it.
178 * We only grow the list, never remove from it:
179 */
180 struct lock_list {
181 struct list_head entry;
182 struct lock_class *class;
183 struct stack_trace trace;
184 int distance;
185 };
186
187 /*
188 * We record lock dependency chains, so that we can cache them:
189 */
190 struct lock_chain {
191 u8 irq_context;
192 u8 depth;
193 u16 base;
194 struct list_head entry;
195 u64 chain_key;
196 };
197
198 #define MAX_LOCKDEP_KEYS_BITS 13
199 /*
200 * Subtract one because we offset hlock->class_idx by 1 in order
201 * to make 0 mean no class. This avoids overflowing the class_idx
202 * bitfield and hitting the BUG in hlock_class().
203 */
204 #define MAX_LOCKDEP_KEYS ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
205
206 struct held_lock {
207 /*
208 * One-way hash of the dependency chain up to this point. We
209 * hash the hashes step by step as the dependency chain grows.
210 *
211 * We use it for dependency-caching and we skip detection
212 * passes and dependency-updates if there is a cache-hit, so
213 * it is absolutely critical for 100% coverage of the validator
214 * to have a unique key value for every unique dependency path
215 * that can occur in the system, to make a unique hash value
216 * as likely as possible - hence the 64-bit width.
217 *
218 * The task struct holds the current hash value (initialized
219 * with zero), here we store the previous hash value:
220 */
221 u64 prev_chain_key;
222 unsigned long acquire_ip;
223 struct lockdep_map *instance;
224 struct lockdep_map *nest_lock;
225 #ifdef CONFIG_LOCK_STAT
226 u64 waittime_stamp;
227 u64 holdtime_stamp;
228 #endif
229 unsigned int class_idx:MAX_LOCKDEP_KEYS_BITS;
230 /*
231 * The lock-stack is unified in that the lock chains of interrupt
232 * contexts nest ontop of process context chains, but we 'separate'
233 * the hashes by starting with 0 if we cross into an interrupt
234 * context, and we also keep do not add cross-context lock
235 * dependencies - the lock usage graph walking covers that area
236 * anyway, and we'd just unnecessarily increase the number of
237 * dependencies otherwise. [Note: hardirq and softirq contexts
238 * are separated from each other too.]
239 *
240 * The following field is used to detect when we cross into an
241 * interrupt context:
242 */
243 unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
244 unsigned int trylock:1;
245 unsigned int read:2; /* see lock_acquire() comment */
246 unsigned int check:2; /* see lock_acquire() comment */
247 unsigned int hardirqs_off:1;
248 };
249
250 /*
251 * Initialization, self-test and debugging-output methods:
252 */
253 extern void lockdep_init(void);
254 extern void lockdep_info(void);
255 extern void lockdep_reset(void);
256 extern void lockdep_reset_lock(struct lockdep_map *lock);
257 extern void lockdep_free_key_range(void *start, unsigned long size);
258 extern void lockdep_sys_exit(void);
259
260 extern void lockdep_off(void);
261 extern void lockdep_on(void);
262
263 /*
264 * These methods are used by specific locking variants (spinlocks,
265 * rwlocks, mutexes and rwsems) to pass init/acquire/release events
266 * to lockdep:
267 */
268
269 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
270 struct lock_class_key *key, int subclass);
271
272 /*
273 * To initialize a lockdep_map statically use this macro.
274 * Note that _name must not be NULL.
275 */
276 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
277 { .name = (_name), .key = (void *)(_key), }
278
279 /*
280 * Reinitialize a lock key - for cases where there is special locking or
281 * special initialization of locks so that the validator gets the scope
282 * of dependencies wrong: they are either too broad (they need a class-split)
283 * or they are too narrow (they suffer from a false class-split):
284 */
285 #define lockdep_set_class(lock, key) \
286 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
287 #define lockdep_set_class_and_name(lock, key, name) \
288 lockdep_init_map(&(lock)->dep_map, name, key, 0)
289 #define lockdep_set_class_and_subclass(lock, key, sub) \
290 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
291 #define lockdep_set_subclass(lock, sub) \
292 lockdep_init_map(&(lock)->dep_map, #lock, \
293 (lock)->dep_map.key, sub)
294
295 /*
296 * Acquire a lock.
297 *
298 * Values for "read":
299 *
300 * 0: exclusive (write) acquire
301 * 1: read-acquire (no recursion allowed)
302 * 2: read-acquire with same-instance recursion allowed
303 *
304 * Values for check:
305 *
306 * 0: disabled
307 * 1: simple checks (freeing, held-at-exit-time, etc.)
308 * 2: full validation
309 */
310 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
311 int trylock, int read, int check,
312 struct lockdep_map *nest_lock, unsigned long ip);
313
314 extern void lock_release(struct lockdep_map *lock, int nested,
315 unsigned long ip);
316
317 extern void lock_set_class(struct lockdep_map *lock, const char *name,
318 struct lock_class_key *key, unsigned int subclass,
319 unsigned long ip);
320
lock_set_subclass(struct lockdep_map * lock,unsigned int subclass,unsigned long ip)321 static inline void lock_set_subclass(struct lockdep_map *lock,
322 unsigned int subclass, unsigned long ip)
323 {
324 lock_set_class(lock, lock->name, lock->key, subclass, ip);
325 }
326
327 # define INIT_LOCKDEP .lockdep_recursion = 0,
328
329 #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
330
331 #else /* !LOCKDEP */
332
lockdep_off(void)333 static inline void lockdep_off(void)
334 {
335 }
336
lockdep_on(void)337 static inline void lockdep_on(void)
338 {
339 }
340
341 # define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
342 # define lock_release(l, n, i) do { } while (0)
343 # define lock_set_class(l, n, k, s, i) do { } while (0)
344 # define lock_set_subclass(l, s, i) do { } while (0)
345 # define lockdep_init() do { } while (0)
346 # define lockdep_info() do { } while (0)
347 # define lockdep_init_map(lock, name, key, sub) \
348 do { (void)(name); (void)(key); } while (0)
349 # define lockdep_set_class(lock, key) do { (void)(key); } while (0)
350 # define lockdep_set_class_and_name(lock, key, name) \
351 do { (void)(key); (void)(name); } while (0)
352 #define lockdep_set_class_and_subclass(lock, key, sub) \
353 do { (void)(key); } while (0)
354 #define lockdep_set_subclass(lock, sub) do { } while (0)
355
356 # define INIT_LOCKDEP
357 # define lockdep_reset() do { debug_locks = 1; } while (0)
358 # define lockdep_free_key_range(start, size) do { } while (0)
359 # define lockdep_sys_exit() do { } while (0)
360 /*
361 * The class key takes no space if lockdep is disabled:
362 */
363 struct lock_class_key { };
364
365 #define lockdep_depth(tsk) (0)
366
367 #endif /* !LOCKDEP */
368
369 #ifdef CONFIG_LOCK_STAT
370
371 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
372 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
373
374 #define LOCK_CONTENDED(_lock, try, lock) \
375 do { \
376 if (!try(_lock)) { \
377 lock_contended(&(_lock)->dep_map, _RET_IP_); \
378 lock(_lock); \
379 } \
380 lock_acquired(&(_lock)->dep_map, _RET_IP_); \
381 } while (0)
382
383 #else /* CONFIG_LOCK_STAT */
384
385 #define lock_contended(lockdep_map, ip) do {} while (0)
386 #define lock_acquired(lockdep_map, ip) do {} while (0)
387
388 #define LOCK_CONTENDED(_lock, try, lock) \
389 lock(_lock)
390
391 #endif /* CONFIG_LOCK_STAT */
392
393 #ifdef CONFIG_GENERIC_HARDIRQS
394 extern void early_init_irq_lock_class(void);
395 #else
early_init_irq_lock_class(void)396 static inline void early_init_irq_lock_class(void)
397 {
398 }
399 #endif
400
401 #ifdef CONFIG_TRACE_IRQFLAGS
402 extern void early_boot_irqs_off(void);
403 extern void early_boot_irqs_on(void);
404 extern void print_irqtrace_events(struct task_struct *curr);
405 #else
early_boot_irqs_off(void)406 static inline void early_boot_irqs_off(void)
407 {
408 }
early_boot_irqs_on(void)409 static inline void early_boot_irqs_on(void)
410 {
411 }
print_irqtrace_events(struct task_struct * curr)412 static inline void print_irqtrace_events(struct task_struct *curr)
413 {
414 }
415 #endif
416
417 /*
418 * For trivial one-depth nesting of a lock-class, the following
419 * global define can be used. (Subsystems with multiple levels
420 * of nesting should define their own lock-nesting subclasses.)
421 */
422 #define SINGLE_DEPTH_NESTING 1
423
424 /*
425 * Map the dependency ops to NOP or to real lockdep ops, depending
426 * on the per lock-class debug mode:
427 */
428
429 #ifdef CONFIG_DEBUG_LOCK_ALLOC
430 # ifdef CONFIG_PROVE_LOCKING
431 # define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
432 # define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
433 # else
434 # define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
435 # define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, NULL, i)
436 # endif
437 # define spin_release(l, n, i) lock_release(l, n, i)
438 #else
439 # define spin_acquire(l, s, t, i) do { } while (0)
440 # define spin_release(l, n, i) do { } while (0)
441 #endif
442
443 #ifdef CONFIG_DEBUG_LOCK_ALLOC
444 # ifdef CONFIG_PROVE_LOCKING
445 # define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
446 # define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, NULL, i)
447 # else
448 # define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
449 # define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, NULL, i)
450 # endif
451 # define rwlock_release(l, n, i) lock_release(l, n, i)
452 #else
453 # define rwlock_acquire(l, s, t, i) do { } while (0)
454 # define rwlock_acquire_read(l, s, t, i) do { } while (0)
455 # define rwlock_release(l, n, i) do { } while (0)
456 #endif
457
458 #ifdef CONFIG_DEBUG_LOCK_ALLOC
459 # ifdef CONFIG_PROVE_LOCKING
460 # define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
461 # else
462 # define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
463 # endif
464 # define mutex_release(l, n, i) lock_release(l, n, i)
465 #else
466 # define mutex_acquire(l, s, t, i) do { } while (0)
467 # define mutex_release(l, n, i) do { } while (0)
468 #endif
469
470 #ifdef CONFIG_DEBUG_LOCK_ALLOC
471 # ifdef CONFIG_PROVE_LOCKING
472 # define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
473 # define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, NULL, i)
474 # else
475 # define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
476 # define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, NULL, i)
477 # endif
478 # define rwsem_release(l, n, i) lock_release(l, n, i)
479 #else
480 # define rwsem_acquire(l, s, t, i) do { } while (0)
481 # define rwsem_acquire_read(l, s, t, i) do { } while (0)
482 # define rwsem_release(l, n, i) do { } while (0)
483 #endif
484
485 #ifdef CONFIG_DEBUG_LOCK_ALLOC
486 # ifdef CONFIG_PROVE_LOCKING
487 # define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
488 # else
489 # define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
490 # endif
491 # define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
492 #else
493 # define lock_map_acquire(l) do { } while (0)
494 # define lock_map_release(l) do { } while (0)
495 #endif
496
497 #ifdef CONFIG_PROVE_LOCKING
498 # define might_lock(lock) \
499 do { \
500 typecheck(struct lockdep_map *, &(lock)->dep_map); \
501 lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_); \
502 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
503 } while (0)
504 # define might_lock_read(lock) \
505 do { \
506 typecheck(struct lockdep_map *, &(lock)->dep_map); \
507 lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_); \
508 lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
509 } while (0)
510 #else
511 # define might_lock(lock) do { } while (0)
512 # define might_lock_read(lock) do { } while (0)
513 #endif
514
515 #endif /* __LINUX_LOCKDEP_H */
516