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 #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  * We'd rather not expose kernel/lockdep_states.h this wide, but we do need
  24  * the total number of states... :-(
  25  */
  26 #define XXX_LOCK_USAGE_STATES           (1+3*4)
  27
  28 #define MAX_LOCKDEP_SUBCLASSES          8UL
  29
  30 /*
  31  * Lock-classes are keyed via unique addresses, by embedding the
  32  * lockclass-key into the kernel (or module) .data section. (For
  33  * static locks we use the lock address itself as the key.)
  34  */
  35 struct lockdep_subclass_key {
  36         char __one_byte;
  37 } __attribute__ ((__packed__));
  38
  39 struct lock_class_key {
  40         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  41 };
  42
  43 #define LOCKSTAT_POINTS         4
  44
  45 /*
  46  * The lock-class itself:
  47  */
  48 struct lock_class {
  49         /*
  50          * class-hash:
  51          */
  52         struct list_head                hash_entry;
  53
  54         /*
  55          * global list of all lock-classes:
  56          */
  57         struct list_head                lock_entry;
  58
  59         struct lockdep_subclass_key     *key;
  60         unsigned int                    subclass;
  61         unsigned int                    dep_gen_id;
  62
  63         /*
  64          * IRQ/softirq usage tracking bits:
  65          */
  66         unsigned long                   usage_mask;
  67         struct stack_trace              usage_traces[XXX_LOCK_USAGE_STATES];
  68
  69         /*
  70          * These fields represent a directed graph of lock dependencies,
  71          * to every node we attach a list of "forward" and a list of
  72          * "backward" graph nodes.
  73          */
  74         struct list_head                locks_after, locks_before;
  75
  76         /*
  77          * Generation counter, when doing certain classes of graph walking,
  78          * to ensure that we check one node only once:
  79          */
  80         unsigned int                    version;
  81
  82         /*
  83          * Statistics counter:
  84          */
  85         unsigned long                   ops;
  86
  87         const char                      *name;
  88         int                             name_version;
  89
  90 #ifdef CONFIG_LOCK_STAT
  91         unsigned long                   contention_point[LOCKSTAT_POINTS];
  92         unsigned long                   contending_point[LOCKSTAT_POINTS];
  93 #endif
  94 };
  95
  96 #ifdef CONFIG_LOCK_STAT
  97 struct lock_time {
  98         s64                             min;
  99         s64                             max;
 100         s64                             total;
 101         unsigned long                   nr;
 102 };
 103
 104 enum bounce_type {
 105         bounce_acquired_write,
 106         bounce_acquired_read,
 107         bounce_contended_write,
 108         bounce_contended_read,
 109         nr_bounce_types,
 110
 111         bounce_acquired = bounce_acquired_write,
 112         bounce_contended = bounce_contended_write,
 113 };
 114
 115 struct lock_class_stats {
 116         unsigned long                   contention_point[4];
 117         unsigned long                   contending_point[4];
 118         struct lock_time                read_waittime;
 119         struct lock_time                write_waittime;
 120         struct lock_time                read_holdtime;
 121         struct lock_time                write_holdtime;
 122         unsigned long                   bounces[nr_bounce_types];
 123 };
 124
 125 struct lock_class_stats lock_stats(struct lock_class *class);
 126 void clear_lock_stats(struct lock_class *class);
 127 #endif
 128
 129 /*
 130  * Map the lock object (the lock instance) to the lock-class object.
 131  * This is embedded into specific lock instances:
 132  */
 133 struct lockdep_map {
 134         struct lock_class_key           *key;
 135         struct lock_class               *class_cache;
 136         const char                      *name;
 137 #ifdef CONFIG_LOCK_STAT
 138         int                             cpu;
 139         unsigned long                   ip;
 140 #endif
 141 };
 142
 143 /*
 144  * Every lock has a list of other locks that were taken after it.
 145  * We only grow the list, never remove from it:
 146  */
 147 struct lock_list {
 148         struct list_head                entry;
 149         struct lock_class               *class;
 150         struct stack_trace              trace;
 151         int                             distance;
 152
 153         /*
 154          * The parent field is used to implement breadth-first search, and the
 155          * bit 0 is reused to indicate if the lock has been accessed in BFS.
 156          */
 157         struct lock_list                *parent;
 158 };
 159
 160 /*
 161  * We record lock dependency chains, so that we can cache them:
 162  */
 163 struct lock_chain {
 164         u8                              irq_context;
 165         u8                              depth;
 166         u16                             base;
 167         struct list_head                entry;
 168         u64                             chain_key;
 169 };
 170
 171 #define MAX_LOCKDEP_KEYS_BITS           13
 172 /*
 173  * Subtract one because we offset hlock->class_idx by 1 in order
 174  * to make 0 mean no class. This avoids overflowing the class_idx
 175  * bitfield and hitting the BUG in hlock_class().
 176  */
 177 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 178
 179 struct held_lock {
 180         /*
 181          * One-way hash of the dependency chain up to this point. We
 182          * hash the hashes step by step as the dependency chain grows.
 183          *
 184          * We use it for dependency-caching and we skip detection
 185          * passes and dependency-updates if there is a cache-hit, so
 186          * it is absolutely critical for 100% coverage of the validator
 187          * to have a unique key value for every unique dependency path
 188          * that can occur in the system, to make a unique hash value
 189          * as likely as possible - hence the 64-bit width.
 190          *
 191          * The task struct holds the current hash value (initialized
 192          * with zero), here we store the previous hash value:
 193          */
 194         u64                             prev_chain_key;
 195         unsigned long                   acquire_ip;
 196         struct lockdep_map              *instance;
 197         struct lockdep_map              *nest_lock;
 198 #ifdef CONFIG_LOCK_STAT
 199         u64                             waittime_stamp;
 200         u64                             holdtime_stamp;
 201 #endif
 202         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 203         /*
 204          * The lock-stack is unified in that the lock chains of interrupt
 205          * contexts nest ontop of process context chains, but we 'separate'
 206          * the hashes by starting with 0 if we cross into an interrupt
 207          * context, and we also keep do not add cross-context lock
 208          * dependencies - the lock usage graph walking covers that area
 209          * anyway, and we'd just unnecessarily increase the number of
 210          * dependencies otherwise. [Note: hardirq and softirq contexts
 211          * are separated from each other too.]
 212          *
 213          * The following field is used to detect when we cross into an
 214          * interrupt context:
 215          */
 216         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 217         unsigned int trylock:1;                                         /* 16 bits */
 218
 219         unsigned int read:2;        /* see lock_acquire() comment */
 220         unsigned int check:2;       /* see lock_acquire() comment */
 221         unsigned int hardirqs_off:1;
 222         unsigned int references:11;                                     /* 32 bits */
 223 };
 224
 225 /*
 226  * Initialization, self-test and debugging-output methods:
 227  */
 228 extern void lockdep_init(void);
 229 extern void lockdep_info(void);
 230 extern void lockdep_reset(void);
 231 extern void lockdep_reset_lock(struct lockdep_map *lock);
 232 extern void lockdep_free_key_range(void *start, unsigned long size);
 233 extern void lockdep_sys_exit(void);
 234
 235 extern void lockdep_off(void);
 236 extern void lockdep_on(void);
 237
 238 /*
 239  * These methods are used by specific locking variants (spinlocks,
 240  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 241  * to lockdep:
 242  */
 243
 244 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 245                              struct lock_class_key *key, int subclass);
 246
 247 /*
 248  * To initialize a lockdep_map statically use this macro.
 249  * Note that _name must not be NULL.
 250  */
 251 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 252         { .name = (_name), .key = (void *)(_key), }
 253
 254 /*
 255  * Reinitialize a lock key - for cases where there is special locking or
 256  * special initialization of locks so that the validator gets the scope
 257  * of dependencies wrong: they are either too broad (they need a class-split)
 258  * or they are too narrow (they suffer from a false class-split):
 259  */
 260 #define lockdep_set_class(lock, key) \
 261                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 262 #define lockdep_set_class_and_name(lock, key, name) \
 263                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 264 #define lockdep_set_class_and_subclass(lock, key, sub) \
 265                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 266 #define lockdep_set_subclass(lock, sub) \
 267                 lockdep_init_map(&(lock)->dep_map, #lock, \
 268                                  (lock)->dep_map.key, sub)
 269 /*
 270  * Compare locking classes
 271  */
 272 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
 273
 274 static inline int lockdep_match_key(struct lockdep_map *lock,
 275                                     struct lock_class_key *key)
 276 {
 277         return lock->key == key;
 278 }
 279
 280 /*
 281  * Acquire a lock.
 282  *
 283  * Values for "read":
 284  *
 285  *   0: exclusive (write) acquire
 286  *   1: read-acquire (no recursion allowed)
 287  *   2: read-acquire with same-instance recursion allowed
 288  *
 289  * Values for check:
 290  *
 291  *   0: disabled
 292  *   1: simple checks (freeing, held-at-exit-time, etc.)
 293  *   2: full validation
 294  */
 295 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 296                          int trylock, int read, int check,
 297                          struct lockdep_map *nest_lock, unsigned long ip);
 298
 299 extern void lock_release(struct lockdep_map *lock, int nested,
 300                          unsigned long ip);
 301
 302 #define lockdep_is_held(lock)   lock_is_held(&(lock)->dep_map)
 303
 304 extern int lock_is_held(struct lockdep_map *lock);
 305
 306 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 307                            struct lock_class_key *key, unsigned int subclass,
 308                            unsigned long ip);
 309
 310 static inline void lock_set_subclass(struct lockdep_map *lock,
 311                 unsigned int subclass, unsigned long ip)
 312 {
 313         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 314 }
 315
 316 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 317 extern void lockdep_clear_current_reclaim_state(void);
 318 extern void lockdep_trace_alloc(gfp_t mask);
 319
 320 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 321
 322 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 323
 324 #define lockdep_assert_held(l)  WARN_ON(debug_locks && !lockdep_is_held(l))
 325
 326 #else /* !LOCKDEP */
 327
 328 static inline void lockdep_off(void)
 329 {
 330 }
 331
 332 static inline void lockdep_on(void)
 333 {
 334 }
 335
 336 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 337 # define lock_release(l, n, i)                  do { } while (0)
 338 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 339 # define lock_set_subclass(l, s, i)             do { } while (0)
 340 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 341 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 342 # define lockdep_trace_alloc(g)                 do { } while (0)
 343 # define lockdep_init()                         do { } while (0)
 344 # define lockdep_info()                         do { } while (0)
 345 # define lockdep_init_map(lock, name, key, sub) \
 346                 do { (void)(name); (void)(key); } while (0)
 347 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 348 # define lockdep_set_class_and_name(lock, key, name) \
 349                 do { (void)(key); (void)(name); } while (0)
 350 #define lockdep_set_class_and_subclass(lock, key, sub) \
 351                 do { (void)(key); } while (0)
 352 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 353 /*
 354  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
 355  * case since the result is not well defined and the caller should rather
 356  * #ifdef the call himself.
 357  */
 358
 359 # define INIT_LOCKDEP
 360 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 361 # define lockdep_free_key_range(start, size)    do { } while (0)
 362 # define lockdep_sys_exit()                     do { } while (0)
 363 /*
 364  * The class key takes no space if lockdep is disabled:
 365  */
 366 struct lock_class_key { };
 367
 368 #define lockdep_depth(tsk)      (0)
 369
 370 #define lockdep_assert_held(l)                  do { } while (0)
 371
 372 #endif /* !LOCKDEP */
 373
 374 #ifdef CONFIG_LOCK_STAT
 375
 376 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 377 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 378
 379 #define LOCK_CONTENDED(_lock, try, lock)                        \
 380 do {                                                            \
 381         if (!try(_lock)) {                                      \
 382                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 383                 lock(_lock);                                    \
 384         }                                                       \
 385         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 386 } while (0)
 387
 388 #else /* CONFIG_LOCK_STAT */
 389
 390 #define lock_contended(lockdep_map, ip) do {} while (0)
 391 #define lock_acquired(lockdep_map, ip) do {} while (0)
 392
 393 #define LOCK_CONTENDED(_lock, try, lock) \
 394         lock(_lock)
 395
 396 #endif /* CONFIG_LOCK_STAT */
 397
 398 #ifdef CONFIG_LOCKDEP
 399
 400 /*
 401  * On lockdep we dont want the hand-coded irq-enable of
 402  * _raw_*_lock_flags() code, because lockdep assumes
 403  * that interrupts are not re-enabled during lock-acquire:
 404  */
 405 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 406         LOCK_CONTENDED((_lock), (try), (lock))
 407
 408 #else /* CONFIG_LOCKDEP */
 409
 410 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 411         lockfl((_lock), (flags))
 412
 413 #endif /* CONFIG_LOCKDEP */
 414
 415 #ifdef CONFIG_GENERIC_HARDIRQS
 416 extern void early_init_irq_lock_class(void);
 417 #else
 418 static inline void early_init_irq_lock_class(void)
 419 {
 420 }
 421 #endif
 422
 423 #ifdef CONFIG_TRACE_IRQFLAGS
 424 extern void early_boot_irqs_off(void);
 425 extern void early_boot_irqs_on(void);
 426 extern void print_irqtrace_events(struct task_struct *curr);
 427 #else
 428 static inline void early_boot_irqs_off(void)
 429 {
 430 }
 431 static inline void early_boot_irqs_on(void)
 432 {
 433 }
 434 static inline void print_irqtrace_events(struct task_struct *curr)
 435 {
 436 }
 437 #endif
 438
 439 /*
 440  * For trivial one-depth nesting of a lock-class, the following
 441  * global define can be used. (Subsystems with multiple levels
 442  * of nesting should define their own lock-nesting subclasses.)
 443  */
 444 #define SINGLE_DEPTH_NESTING                    1
 445
 446 /*
 447  * Map the dependency ops to NOP or to real lockdep ops, depending
 448  * on the per lock-class debug mode:
 449  */
 450
 451 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 452 # ifdef CONFIG_PROVE_LOCKING
 453 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 454 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 455 # else
 456 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 457 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 458 # endif
 459 # define spin_release(l, n, i)                  lock_release(l, n, i)
 460 #else
 461 # define spin_acquire(l, s, t, i)               do { } while (0)
 462 # define spin_release(l, n, i)                  do { } while (0)
 463 #endif
 464
 465 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 466 # ifdef CONFIG_PROVE_LOCKING
 467 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 468 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 469 # else
 470 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 471 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 472 # endif
 473 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 474 #else
 475 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 476 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 477 # define rwlock_release(l, n, i)                do { } while (0)
 478 #endif
 479
 480 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 481 # ifdef CONFIG_PROVE_LOCKING
 482 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 483 # else
 484 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 485 # endif
 486 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 487 #else
 488 # define mutex_acquire(l, s, t, i)              do { } while (0)
 489 # define mutex_release(l, n, i)                 do { } while (0)
 490 #endif
 491
 492 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 493 # ifdef CONFIG_PROVE_LOCKING
 494 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 495 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 496 # else
 497 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 498 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 499 # endif
 500 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 501 #else
 502 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 503 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 504 # define rwsem_release(l, n, i)                 do { } while (0)
 505 #endif
 506
 507 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 508 # ifdef CONFIG_PROVE_LOCKING
 509 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 510 # else
 511 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 512 # endif
 513 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 514 #else
 515 # define lock_map_acquire(l)                    do { } while (0)
 516 # define lock_map_release(l)                    do { } while (0)
 517 #endif
 518
 519 #ifdef CONFIG_PROVE_LOCKING
 520 # define might_lock(lock)                                               \
 521 do {                                                                    \
 522         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 523         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 524         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 525 } while (0)
 526 # define might_lock_read(lock)                                          \
 527 do {                                                                    \
 528         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 529         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 530         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 531 } while (0)
 532 #else
 533 # define might_lock(lock) do { } while (0)
 534 # define might_lock_read(lock) do { } while (0)
 535 #endif
 536
 537 #endif /* __LINUX_LOCKDEP_H */