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  * 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
 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
 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
 348 static inline void lockdep_off(void)
 349 {
 350 }
 351
 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 early_boot_irqs_off(void);
 440 extern void early_boot_irqs_on(void);
 441 extern void print_irqtrace_events(struct task_struct *curr);
 442 #else
 443 static inline void early_boot_irqs_off(void)
 444 {
 445 }
 446 static inline void early_boot_irqs_on(void)
 447 {
 448 }
 449 static inline void print_irqtrace_events(struct task_struct *curr)
 450 {
 451 }
 452 #endif
 453
 454 /*
 455  * For trivial one-depth nesting of a lock-class, the following
 456  * global define can be used. (Subsystems with multiple levels
 457  * of nesting should define their own lock-nesting subclasses.)
 458  */
 459 #define SINGLE_DEPTH_NESTING                    1
 460
 461 /*
 462  * Map the dependency ops to NOP or to real lockdep ops, depending
 463  * on the per lock-class debug mode:
 464  */
 465
 466 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 467 # ifdef CONFIG_PROVE_LOCKING
 468 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 469 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 470 # else
 471 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 472 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 473 # endif
 474 # define spin_release(l, n, i)                  lock_release(l, n, i)
 475 #else
 476 # define spin_acquire(l, s, t, i)               do { } while (0)
 477 # define spin_release(l, n, i)                  do { } while (0)
 478 #endif
 479
 480 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 481 # ifdef CONFIG_PROVE_LOCKING
 482 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 483 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 484 # else
 485 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 486 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 487 # endif
 488 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 489 #else
 490 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 491 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 492 # define rwlock_release(l, n, i)                do { } while (0)
 493 #endif
 494
 495 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 496 # ifdef CONFIG_PROVE_LOCKING
 497 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 498 # else
 499 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 500 # endif
 501 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 502 #else
 503 # define mutex_acquire(l, s, t, i)              do { } while (0)
 504 # define mutex_release(l, n, i)                 do { } while (0)
 505 #endif
 506
 507 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 508 # ifdef CONFIG_PROVE_LOCKING
 509 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 510 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 511 # else
 512 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 513 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 514 # endif
 515 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 516 #else
 517 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 518 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 519 # define rwsem_release(l, n, i)                 do { } while (0)
 520 #endif
 521
 522 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 523 # ifdef CONFIG_PROVE_LOCKING
 524 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 525 # else
 526 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 527 # endif
 528 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 529 #else
 530 # define lock_map_acquire(l)                    do { } while (0)
 531 # define lock_map_release(l)                    do { } while (0)
 532 #endif
 533
 534 #ifdef CONFIG_PROVE_LOCKING
 535 # define might_lock(lock)                                               \
 536 do {                                                                    \
 537         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 538         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 539         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 540 } while (0)
 541 # define might_lock_read(lock)                                          \
 542 do {                                                                    \
 543         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 544         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 545         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 546 } while (0)
 547 #else
 548 # define might_lock(lock) do { } while (0)
 549 # define might_lock_read(lock) do { } while (0)
 550 #endif
 551
 552 #ifdef CONFIG_PROVE_RCU
 553 extern void lockdep_rcu_dereference(const char *file, const int line);
 554 #endif
 555
 556 #endif /* __LINUX_LOCKDEP_H */