include/linux/lockdep.h

   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  * Lock-classes are keyed via unique addresses, by embedding the
  36  * lockclass-key into the kernel (or module) .data section. (For
  37  * static locks we use the lock address itself as the key.)
  38  */
  39 struct lockdep_subclass_key {
  40         char __one_byte;
  41 } __attribute__ ((__packed__));
  42
  43 struct lock_class_key {
  44         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  45 };
  46
  47 extern struct lock_class_key __lockdep_no_validate__;
  48
  49 #define LOCKSTAT_POINTS         4
  50
  51 /*
  52  * The lock-class itself:
  53  */
  54 struct lock_class {
  55         /*
  56          * class-hash:
  57          */
  58         struct list_head                hash_entry;
  59
  60         /*
  61          * global list of all lock-classes:
  62          */
  63         struct list_head                lock_entry;
  64
  65         struct lockdep_subclass_key     *key;
  66         unsigned int                    subclass;
  67         unsigned int                    dep_gen_id;
  68
  69         /*
  70          * IRQ/softirq usage tracking bits:
  71          */
  72         unsigned long                   usage_mask;
  73         struct stack_trace              usage_traces[XXX_LOCK_USAGE_STATES];
  74
  75         /*
  76          * These fields represent a directed graph of lock dependencies,
  77          * to every node we attach a list of "forward" and a list of
  78          * "backward" graph nodes.
  79          */
  80         struct list_head                locks_after, locks_before;
  81
  82         /*
  83          * Generation counter, when doing certain classes of graph walking,
  84          * to ensure that we check one node only once:
  85          */
  86         unsigned int                    version;
  87
  88         /*
  89          * Statistics counter:
  90          */
  91         unsigned long                   ops;
  92
  93         const char                      *name;
  94         int                             name_version;
  95
  96 #ifdef CONFIG_LOCK_STAT
  97         unsigned long                   contention_point[LOCKSTAT_POINTS];
  98         unsigned long                   contending_point[LOCKSTAT_POINTS];
  99 #endif
 100 };
 101
 102 #ifdef CONFIG_LOCK_STAT
 103 struct lock_time {
 104         s64                             min;
 105         s64                             max;
 106         s64                             total;
 107         unsigned long                   nr;
 108 };
 109
 110 enum bounce_type {
 111         bounce_acquired_write,
 112         bounce_acquired_read,
 113         bounce_contended_write,
 114         bounce_contended_read,
 115         nr_bounce_types,
 116
 117         bounce_acquired = bounce_acquired_write,
 118         bounce_contended = bounce_contended_write,
 119 };
 120
 121 struct lock_class_stats {
 122         unsigned long                   contention_point[4];
 123         unsigned long                   contending_point[4];
 124         struct lock_time                read_waittime;
 125         struct lock_time                write_waittime;
 126         struct lock_time                read_holdtime;
 127         struct lock_time                write_holdtime;
 128         unsigned long                   bounces[nr_bounce_types];
 129 };
 130
 131 struct lock_class_stats lock_stats(struct lock_class *class);
 132 void clear_lock_stats(struct lock_class *class);
 133 #endif
 134
 135 /*
 136  * Map the lock object (the lock instance) to the lock-class object.
 137  * This is embedded into specific lock instances:
 138  */
 139 struct lockdep_map {
 140         struct lock_class_key           *key;
 141         struct lock_class               *class_cache;
 142         const char                      *name;
 143 #ifdef CONFIG_LOCK_STAT
 144         int                             cpu;
 145         unsigned long                   ip;
 146 #endif
 147 };
 148
 149 /*
 150  * Every lock has a list of other locks that were taken after it.
 151  * We only grow the list, never remove from it:
 152  */
 153 struct lock_list {
 154         struct list_head                entry;
 155         struct lock_class               *class;
 156         struct stack_trace              trace;
 157         int                             distance;
 158
 159         /*
 160          * The parent field is used to implement breadth-first search, and the
 161          * bit 0 is reused to indicate if the lock has been accessed in BFS.
 162          */
 163         struct lock_list                *parent;
 164 };
 165
 166 /*
 167  * We record lock dependency chains, so that we can cache them:
 168  */
 169 struct lock_chain {
 170         u8                              irq_context;
 171         u8                              depth;
 172         u16                             base;
 173         struct list_head                entry;
 174         u64                             chain_key;
 175 };
 176
 177 #define MAX_LOCKDEP_KEYS_BITS           13
 178 /*
 179  * Subtract one because we offset hlock->class_idx by 1 in order
 180  * to make 0 mean no class. This avoids overflowing the class_idx
 181  * bitfield and hitting the BUG in hlock_class().
 182  */
 183 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 184
 185 struct held_lock {
 186         /*
 187          * One-way hash of the dependency chain up to this point. We
 188          * hash the hashes step by step as the dependency chain grows.
 189          *
 190          * We use it for dependency-caching and we skip detection
 191          * passes and dependency-updates if there is a cache-hit, so
 192          * it is absolutely critical for 100% coverage of the validator
 193          * to have a unique key value for every unique dependency path
 194          * that can occur in the system, to make a unique hash value
 195          * as likely as possible - hence the 64-bit width.
 196          *
 197          * The task struct holds the current hash value (initialized
 198          * with zero), here we store the previous hash value:
 199          */
 200         u64                             prev_chain_key;
 201         unsigned long                   acquire_ip;
 202         struct lockdep_map              *instance;
 203         struct lockdep_map              *nest_lock;
 204 #ifdef CONFIG_LOCK_STAT
 205         u64                             waittime_stamp;
 206         u64                             holdtime_stamp;
 207 #endif
 208         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 209         /*
 210          * The lock-stack is unified in that the lock chains of interrupt
 211          * contexts nest ontop of process context chains, but we 'separate'
 212          * the hashes by starting with 0 if we cross into an interrupt
 213          * context, and we also keep do not add cross-context lock
 214          * dependencies - the lock usage graph walking covers that area
 215          * anyway, and we'd just unnecessarily increase the number of
 216          * dependencies otherwise. [Note: hardirq and softirq contexts
 217          * are separated from each other too.]
 218          *
 219          * The following field is used to detect when we cross into an
 220          * interrupt context:
 221          */
 222         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 223         unsigned int trylock:1;                                         /* 16 bits */
 224
 225         unsigned int read:2;        /* see lock_acquire() comment */
 226         unsigned int check:2;       /* see lock_acquire() comment */
 227         unsigned int hardirqs_off:1;
 228         unsigned int references:11;                                     /* 32 bits */
 229 };
 230
 231 /*
 232  * Initialization, self-test and debugging-output methods:
 233  */
 234 extern void lockdep_init(void);
 235 extern void lockdep_info(void);
 236 extern void lockdep_reset(void);
 237 extern void lockdep_reset_lock(struct lockdep_map *lock);
 238 extern void lockdep_free_key_range(void *start, unsigned long size);
 239 extern void lockdep_sys_exit(void);
 240
 241 extern void lockdep_off(void);
 242 extern void lockdep_on(void);
 243
 244 /*
 245  * These methods are used by specific locking variants (spinlocks,
 246  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 247  * to lockdep:
 248  */
 249
 250 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 251                              struct lock_class_key *key, int subclass);
 252
 253 /*
 254  * To initialize a lockdep_map statically use this macro.
 255  * Note that _name must not be NULL.
 256  */
 257 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 258         { .name = (_name), .key = (void *)(_key), }
 259
 260 /*
 261  * Reinitialize a lock key - for cases where there is special locking or
 262  * special initialization of locks so that the validator gets the scope
 263  * of dependencies wrong: they are either too broad (they need a class-split)
 264  * or they are too narrow (they suffer from a false class-split):
 265  */
 266 #define lockdep_set_class(lock, key) \
 267                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 268 #define lockdep_set_class_and_name(lock, key, name) \
 269                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 270 #define lockdep_set_class_and_subclass(lock, key, sub) \
 271                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 272 #define lockdep_set_subclass(lock, sub) \
 273                 lockdep_init_map(&(lock)->dep_map, #lock, \
 274                                  (lock)->dep_map.key, sub)
 275
 276 #define lockdep_set_novalidate_class(lock) \
 277         lockdep_set_class(lock, &__lockdep_no_validate__)
 278 /*
 279  * Compare locking classes
 280  */
 281 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
 282
 283 static inline int lockdep_match_key(struct lockdep_map *lock,
 284                                     struct lock_class_key *key)
 285 {
 286         return lock->key == key;
 287 }
 288
 289 /*
 290  * Acquire a lock.
 291  *
 292  * Values for "read":
 293  *
 294  *   0: exclusive (write) acquire
 295  *   1: read-acquire (no recursion allowed)
 296  *   2: read-acquire with same-instance recursion allowed
 297  *
 298  * Values for check:
 299  *
 300  *   0: disabled
 301  *   1: simple checks (freeing, held-at-exit-time, etc.)
 302  *   2: full validation
 303  */
 304 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 305                          int trylock, int read, int check,
 306                          struct lockdep_map *nest_lock, unsigned long ip);
 307
 308 extern void lock_release(struct lockdep_map *lock, int nested,
 309                          unsigned long ip);
 310
 311 #define lockdep_is_held(lock)   lock_is_held(&(lock)->dep_map)
 312
 313 extern int lock_is_held(struct lockdep_map *lock);
 314
 315 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 316                            struct lock_class_key *key, unsigned int subclass,
 317                            unsigned long ip);
 318
 319 static inline void lock_set_subclass(struct lockdep_map *lock,
 320                 unsigned int subclass, unsigned long ip)
 321 {
 322         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 323 }
 324
 325 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 326 extern void lockdep_clear_current_reclaim_state(void);
 327 extern void lockdep_trace_alloc(gfp_t mask);
 328
 329 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 330
 331 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 332
 333 #define lockdep_assert_held(l)  WARN_ON(debug_locks && !lockdep_is_held(l))
 334
 335 #else /* !LOCKDEP */
 336
 337 static inline void lockdep_off(void)
 338 {
 339 }
 340
 341 static inline void lockdep_on(void)
 342 {
 343 }
 344
 345 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 346 # define lock_release(l, n, i)                  do { } while (0)
 347 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 348 # define lock_set_subclass(l, s, i)             do { } while (0)
 349 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 350 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 351 # define lockdep_trace_alloc(g)                 do { } while (0)
 352 # define lockdep_init()                         do { } while (0)
 353 # define lockdep_info()                         do { } while (0)
 354 # define lockdep_init_map(lock, name, key, sub) \
 355                 do { (void)(name); (void)(key); } while (0)
 356 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 357 # define lockdep_set_class_and_name(lock, key, name) \
 358                 do { (void)(key); (void)(name); } while (0)
 359 #define lockdep_set_class_and_subclass(lock, key, sub) \
 360                 do { (void)(key); } while (0)
 361 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 362
 363 #define lockdep_set_novalidate_class(lock) do { } while (0)
 364
 365 /*
 366  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
 367  * case since the result is not well defined and the caller should rather
 368  * #ifdef the call himself.
 369  */
 370
 371 # define INIT_LOCKDEP
 372 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 373 # define lockdep_free_key_range(start, size)    do { } while (0)
 374 # define lockdep_sys_exit()                     do { } while (0)
 375 /*
 376  * The class key takes no space if lockdep is disabled:
 377  */
 378 struct lock_class_key { };
 379
 380 #define lockdep_depth(tsk)      (0)
 381
 382 #define lockdep_assert_held(l)                  do { } while (0)
 383
 384 #endif /* !LOCKDEP */
 385
 386 #ifdef CONFIG_LOCK_STAT
 387
 388 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 389 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 390
 391 #define LOCK_CONTENDED(_lock, try, lock)                        \
 392 do {                                                            \
 393         if (!try(_lock)) {                                      \
 394                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 395                 lock(_lock);                                    \
 396         }                                                       \
 397         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 398 } while (0)
 399
 400 #else /* CONFIG_LOCK_STAT */
 401
 402 #define lock_contended(lockdep_map, ip) do {} while (0)
 403 #define lock_acquired(lockdep_map, ip) do {} while (0)
 404
 405 #define LOCK_CONTENDED(_lock, try, lock) \
 406         lock(_lock)
 407
 408 #endif /* CONFIG_LOCK_STAT */
 409
 410 #ifdef CONFIG_LOCKDEP
 411
 412 /*
 413  * On lockdep we dont want the hand-coded irq-enable of
 414  * _raw_*_lock_flags() code, because lockdep assumes
 415  * that interrupts are not re-enabled during lock-acquire:
 416  */
 417 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 418         LOCK_CONTENDED((_lock), (try), (lock))
 419
 420 #else /* CONFIG_LOCKDEP */
 421
 422 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 423         lockfl((_lock), (flags))
 424
 425 #endif /* CONFIG_LOCKDEP */
 426
 427 #ifdef CONFIG_GENERIC_HARDIRQS
 428 extern void early_init_irq_lock_class(void);
 429 #else
 430 static inline void early_init_irq_lock_class(void)
 431 {
 432 }
 433 #endif
 434
 435 #ifdef CONFIG_TRACE_IRQFLAGS
 436 extern void early_boot_irqs_off(void);
 437 extern void early_boot_irqs_on(void);
 438 extern void print_irqtrace_events(struct task_struct *curr);
 439 #else
 440 static inline void early_boot_irqs_off(void)
 441 {
 442 }
 443 static inline void early_boot_irqs_on(void)
 444 {
 445 }
 446 static inline void print_irqtrace_events(struct task_struct *curr)
 447 {
 448 }
 449 #endif
 450
 451 /*
 452  * For trivial one-depth nesting of a lock-class, the following
 453  * global define can be used. (Subsystems with multiple levels
 454  * of nesting should define their own lock-nesting subclasses.)
 455  */
 456 #define SINGLE_DEPTH_NESTING                    1
 457
 458 /*
 459  * Map the dependency ops to NOP or to real lockdep ops, depending
 460  * on the per lock-class debug mode:
 461  */
 462
 463 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 464 # ifdef CONFIG_PROVE_LOCKING
 465 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 466 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 467 # else
 468 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 469 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 470 # endif
 471 # define spin_release(l, n, i)                  lock_release(l, n, i)
 472 #else
 473 # define spin_acquire(l, s, t, i)               do { } while (0)
 474 # define spin_release(l, n, i)                  do { } while (0)
 475 #endif
 476
 477 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 478 # ifdef CONFIG_PROVE_LOCKING
 479 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 480 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 481 # else
 482 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 483 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 484 # endif
 485 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 486 #else
 487 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 488 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 489 # define rwlock_release(l, n, i)                do { } while (0)
 490 #endif
 491
 492 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 493 # ifdef CONFIG_PROVE_LOCKING
 494 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 495 # else
 496 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 497 # endif
 498 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 499 #else
 500 # define mutex_acquire(l, s, t, i)              do { } while (0)
 501 # define mutex_release(l, n, i)                 do { } while (0)
 502 #endif
 503
 504 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 505 # ifdef CONFIG_PROVE_LOCKING
 506 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 507 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 508 # else
 509 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 510 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 511 # endif
 512 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 513 #else
 514 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 515 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 516 # define rwsem_release(l, n, i)                 do { } while (0)
 517 #endif
 518
 519 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 520 # ifdef CONFIG_PROVE_LOCKING
 521 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 522 # else
 523 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 524 # endif
 525 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 526 #else
 527 # define lock_map_acquire(l)                    do { } while (0)
 528 # define lock_map_release(l)                    do { } while (0)
 529 #endif
 530
 531 #ifdef CONFIG_PROVE_LOCKING
 532 # define might_lock(lock)                                               \
 533 do {                                                                    \
 534         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 535         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 536         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 537 } while (0)
 538 # define might_lock_read(lock)                                          \
 539 do {                                                                    \
 540         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 541         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 542         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 543 } while (0)
 544 #else
 545 # define might_lock(lock) do { } while (0)
 546 # define might_lock_read(lock) do { } while (0)
 547 #endif
 548
 549 #ifdef CONFIG_PROVE_RCU
 550 extern void lockdep_rcu_dereference(const char *file, const int line);
 551 #endif
 552
 553 #endif /* __LINUX_LOCKDEP_H */