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
   6  *
   7  * see Documentation/locking/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 hlist_node               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[LOCKSTAT_POINTS];
 134         unsigned long                   contending_point[LOCKSTAT_POINTS];
 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 static inline void lockdep_copy_map(struct lockdep_map *to,
 161                                     struct lockdep_map *from)
 162 {
 163         int i;
 164
 165         *to = *from;
 166         /*
 167          * Since the class cache can be modified concurrently we could observe
 168          * half pointers (64bit arch using 32bit copy insns). Therefore clear
 169          * the caches and take the performance hit.
 170          *
 171          * XXX it doesn't work well with lockdep_set_class_and_subclass(), since
 172          *     that relies on cache abuse.
 173          */
 174         for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
 175                 to->class_cache[i] = NULL;
 176 }
 177
 178 /*
 179  * Every lock has a list of other locks that were taken after it.
 180  * We only grow the list, never remove from it:
 181  */
 182 struct lock_list {
 183         struct list_head                entry;
 184         struct lock_class               *class;
 185         struct stack_trace              trace;
 186         int                             distance;
 187
 188         /*
 189          * The parent field is used to implement breadth-first search, and the
 190          * bit 0 is reused to indicate if the lock has been accessed in BFS.
 191          */
 192         struct lock_list                *parent;
 193 };
 194
 195 /*
 196  * We record lock dependency chains, so that we can cache them:
 197  */
 198 struct lock_chain {
 199         /* see BUILD_BUG_ON()s in lookup_chain_cache() */
 200         unsigned int                    irq_context :  2,
 201                                         depth       :  6,
 202                                         base        : 24;
 203         /* 4 byte hole */
 204         struct hlist_node               entry;
 205         u64                             chain_key;
 206 };
 207
 208 #define MAX_LOCKDEP_KEYS_BITS           13
 209 /*
 210  * Subtract one because we offset hlock->class_idx by 1 in order
 211  * to make 0 mean no class. This avoids overflowing the class_idx
 212  * bitfield and hitting the BUG in hlock_class().
 213  */
 214 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 215
 216 struct held_lock {
 217         /*
 218          * One-way hash of the dependency chain up to this point. We
 219          * hash the hashes step by step as the dependency chain grows.
 220          *
 221          * We use it for dependency-caching and we skip detection
 222          * passes and dependency-updates if there is a cache-hit, so
 223          * it is absolutely critical for 100% coverage of the validator
 224          * to have a unique key value for every unique dependency path
 225          * that can occur in the system, to make a unique hash value
 226          * as likely as possible - hence the 64-bit width.
 227          *
 228          * The task struct holds the current hash value (initialized
 229          * with zero), here we store the previous hash value:
 230          */
 231         u64                             prev_chain_key;
 232         unsigned long                   acquire_ip;
 233         struct lockdep_map              *instance;
 234         struct lockdep_map              *nest_lock;
 235 #ifdef CONFIG_LOCK_STAT
 236         u64                             waittime_stamp;
 237         u64                             holdtime_stamp;
 238 #endif
 239         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 240         /*
 241          * The lock-stack is unified in that the lock chains of interrupt
 242          * contexts nest ontop of process context chains, but we 'separate'
 243          * the hashes by starting with 0 if we cross into an interrupt
 244          * context, and we also keep do not add cross-context lock
 245          * dependencies - the lock usage graph walking covers that area
 246          * anyway, and we'd just unnecessarily increase the number of
 247          * dependencies otherwise. [Note: hardirq and softirq contexts
 248          * are separated from each other too.]
 249          *
 250          * The following field is used to detect when we cross into an
 251          * interrupt context:
 252          */
 253         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 254         unsigned int trylock:1;                                         /* 16 bits */
 255
 256         unsigned int read:2;        /* see lock_acquire() comment */
 257         unsigned int check:1;       /* see lock_acquire() comment */
 258         unsigned int hardirqs_off:1;
 259         unsigned int references:12;                                     /* 32 bits */
 260         unsigned int pin_count;
 261 };
 262
 263 /*
 264  * Initialization, self-test and debugging-output methods:
 265  */
 266 extern void lockdep_info(void);
 267 extern void lockdep_reset(void);
 268 extern void lockdep_reset_lock(struct lockdep_map *lock);
 269 extern void lockdep_free_key_range(void *start, unsigned long size);
 270 extern asmlinkage void lockdep_sys_exit(void);
 271
 272 extern void lockdep_off(void);
 273 extern void lockdep_on(void);
 274
 275 /*
 276  * These methods are used by specific locking variants (spinlocks,
 277  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 278  * to lockdep:
 279  */
 280
 281 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 282                              struct lock_class_key *key, int subclass);
 283
 284 /*
 285  * To initialize a lockdep_map statically use this macro.
 286  * Note that _name must not be NULL.
 287  */
 288 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 289         { .name = (_name), .key = (void *)(_key), }
 290
 291 /*
 292  * Reinitialize a lock key - for cases where there is special locking or
 293  * special initialization of locks so that the validator gets the scope
 294  * of dependencies wrong: they are either too broad (they need a class-split)
 295  * or they are too narrow (they suffer from a false class-split):
 296  */
 297 #define lockdep_set_class(lock, key) \
 298                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 299 #define lockdep_set_class_and_name(lock, key, name) \
 300                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 301 #define lockdep_set_class_and_subclass(lock, key, sub) \
 302                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 303 #define lockdep_set_subclass(lock, sub) \
 304                 lockdep_init_map(&(lock)->dep_map, #lock, \
 305                                  (lock)->dep_map.key, sub)
 306
 307 #define lockdep_set_novalidate_class(lock) \
 308         lockdep_set_class_and_name(lock, &__lockdep_no_validate__, #lock)
 309 /*
 310  * Compare locking classes
 311  */
 312 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
 313
 314 static inline int lockdep_match_key(struct lockdep_map *lock,
 315                                     struct lock_class_key *key)
 316 {
 317         return lock->key == key;
 318 }
 319
 320 /*
 321  * Acquire a lock.
 322  *
 323  * Values for "read":
 324  *
 325  *   0: exclusive (write) acquire
 326  *   1: read-acquire (no recursion allowed)
 327  *   2: read-acquire with same-instance recursion allowed
 328  *
 329  * Values for check:
 330  *
 331  *   0: simple checks (freeing, held-at-exit-time, etc.)
 332  *   1: full validation
 333  */
 334 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 335                          int trylock, int read, int check,
 336                          struct lockdep_map *nest_lock, unsigned long ip);
 337
 338 extern void lock_release(struct lockdep_map *lock, int nested,
 339                          unsigned long ip);
 340
 341 #define lockdep_is_held(lock)   lock_is_held(&(lock)->dep_map)
 342
 343 extern int lock_is_held(struct lockdep_map *lock);
 344
 345 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 346                            struct lock_class_key *key, unsigned int subclass,
 347                            unsigned long ip);
 348
 349 static inline void lock_set_subclass(struct lockdep_map *lock,
 350                 unsigned int subclass, unsigned long ip)
 351 {
 352         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 353 }
 354
 355 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 356 extern void lockdep_clear_current_reclaim_state(void);
 357 extern void lockdep_trace_alloc(gfp_t mask);
 358
 359 extern void lock_pin_lock(struct lockdep_map *lock);
 360 extern void lock_unpin_lock(struct lockdep_map *lock);
 361
 362 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 363
 364 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 365
 366 #define lockdep_assert_held(l)  do {                            \
 367                 WARN_ON(debug_locks && !lockdep_is_held(l));    \
 368         } while (0)
 369
 370 #define lockdep_assert_held_once(l)     do {                            \
 371                 WARN_ON_ONCE(debug_locks && !lockdep_is_held(l));       \
 372         } while (0)
 373
 374 #define lockdep_recursing(tsk)  ((tsk)->lockdep_recursion)
 375
 376 #define lockdep_pin_lock(l)             lock_pin_lock(&(l)->dep_map)
 377 #define lockdep_unpin_lock(l)   lock_unpin_lock(&(l)->dep_map)
 378
 379 #else /* !CONFIG_LOCKDEP */
 380
 381 static inline void lockdep_off(void)
 382 {
 383 }
 384
 385 static inline void lockdep_on(void)
 386 {
 387 }
 388
 389 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 390 # define lock_release(l, n, i)                  do { } while (0)
 391 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 392 # define lock_set_subclass(l, s, i)             do { } while (0)
 393 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 394 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 395 # define lockdep_trace_alloc(g)                 do { } while (0)
 396 # define lockdep_info()                         do { } while (0)
 397 # define lockdep_init_map(lock, name, key, sub) \
 398                 do { (void)(name); (void)(key); } while (0)
 399 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 400 # define lockdep_set_class_and_name(lock, key, name) \
 401                 do { (void)(key); (void)(name); } while (0)
 402 #define lockdep_set_class_and_subclass(lock, key, sub) \
 403                 do { (void)(key); } while (0)
 404 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 405
 406 #define lockdep_set_novalidate_class(lock) do { } while (0)
 407
 408 /*
 409  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
 410  * case since the result is not well defined and the caller should rather
 411  * #ifdef the call himself.
 412  */
 413
 414 # define INIT_LOCKDEP
 415 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 416 # define lockdep_free_key_range(start, size)    do { } while (0)
 417 # define lockdep_sys_exit()                     do { } while (0)
 418 /*
 419  * The class key takes no space if lockdep is disabled:
 420  */
 421 struct lock_class_key { };
 422
 423 #define lockdep_depth(tsk)      (0)
 424
 425 #define lockdep_assert_held(l)                  do { (void)(l); } while (0)
 426 #define lockdep_assert_held_once(l)             do { (void)(l); } while (0)
 427
 428 #define lockdep_recursing(tsk)                  (0)
 429
 430 #define lockdep_pin_lock(l)                             do { (void)(l); } while (0)
 431 #define lockdep_unpin_lock(l)                   do { (void)(l); } while (0)
 432
 433 #endif /* !LOCKDEP */
 434
 435 #ifdef CONFIG_LOCK_STAT
 436
 437 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 438 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 439
 440 #define LOCK_CONTENDED(_lock, try, lock)                        \
 441 do {                                                            \
 442         if (!try(_lock)) {                                      \
 443                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 444                 lock(_lock);                                    \
 445         }                                                       \
 446         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 447 } while (0)
 448
 449 #else /* CONFIG_LOCK_STAT */
 450
 451 #define lock_contended(lockdep_map, ip) do {} while (0)
 452 #define lock_acquired(lockdep_map, ip) do {} while (0)
 453
 454 #define LOCK_CONTENDED(_lock, try, lock) \
 455         lock(_lock)
 456
 457 #endif /* CONFIG_LOCK_STAT */
 458
 459 #ifdef CONFIG_LOCKDEP
 460
 461 /*
 462  * On lockdep we dont want the hand-coded irq-enable of
 463  * _raw_*_lock_flags() code, because lockdep assumes
 464  * that interrupts are not re-enabled during lock-acquire:
 465  */
 466 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 467         LOCK_CONTENDED((_lock), (try), (lock))
 468
 469 #else /* CONFIG_LOCKDEP */
 470
 471 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 472         lockfl((_lock), (flags))
 473
 474 #endif /* CONFIG_LOCKDEP */
 475
 476 #ifdef CONFIG_TRACE_IRQFLAGS
 477 extern void print_irqtrace_events(struct task_struct *curr);
 478 #else
 479 static inline void print_irqtrace_events(struct task_struct *curr)
 480 {
 481 }
 482 #endif
 483
 484 /*
 485  * For trivial one-depth nesting of a lock-class, the following
 486  * global define can be used. (Subsystems with multiple levels
 487  * of nesting should define their own lock-nesting subclasses.)
 488  */
 489 #define SINGLE_DEPTH_NESTING                    1
 490
 491 /*
 492  * Map the dependency ops to NOP or to real lockdep ops, depending
 493  * on the per lock-class debug mode:
 494  */
 495
 496 #define lock_acquire_exclusive(l, s, t, n, i)           lock_acquire(l, s, t, 0, 1, n, i)
 497 #define lock_acquire_shared(l, s, t, n, i)              lock_acquire(l, s, t, 1, 1, n, i)
 498 #define lock_acquire_shared_recursive(l, s, t, n, i)    lock_acquire(l, s, t, 2, 1, n, i)
 499
 500 #define spin_acquire(l, s, t, i)                lock_acquire_exclusive(l, s, t, NULL, i)
 501 #define spin_acquire_nest(l, s, t, n, i)        lock_acquire_exclusive(l, s, t, n, i)
 502 #define spin_release(l, n, i)                   lock_release(l, n, i)
 503
 504 #define rwlock_acquire(l, s, t, i)              lock_acquire_exclusive(l, s, t, NULL, i)
 505 #define rwlock_acquire_read(l, s, t, i)         lock_acquire_shared_recursive(l, s, t, NULL, i)
 506 #define rwlock_release(l, n, i)                 lock_release(l, n, i)
 507
 508 #define seqcount_acquire(l, s, t, i)            lock_acquire_exclusive(l, s, t, NULL, i)
 509 #define seqcount_acquire_read(l, s, t, i)       lock_acquire_shared_recursive(l, s, t, NULL, i)
 510 #define seqcount_release(l, n, i)               lock_release(l, n, i)
 511
 512 #define mutex_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
 513 #define mutex_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
 514 #define mutex_release(l, n, i)                  lock_release(l, n, i)
 515
 516 #define rwsem_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
 517 #define rwsem_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
 518 #define rwsem_acquire_read(l, s, t, i)          lock_acquire_shared(l, s, t, NULL, i)
 519 #define rwsem_release(l, n, i)                  lock_release(l, n, i)
 520
 521 #define lock_map_acquire(l)                     lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
 522 #define lock_map_acquire_read(l)                lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
 523 #define lock_map_acquire_tryread(l)             lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
 524 #define lock_map_release(l)                     lock_release(l, 1, _THIS_IP_)
 525
 526 #ifdef CONFIG_PROVE_LOCKING
 527 # define might_lock(lock)                                               \
 528 do {                                                                    \
 529         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 530         lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_);    \
 531         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 532 } while (0)
 533 # define might_lock_read(lock)                                          \
 534 do {                                                                    \
 535         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 536         lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_);    \
 537         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 538 } while (0)
 539 #else
 540 # define might_lock(lock) do { } while (0)
 541 # define might_lock_read(lock) do { } while (0)
 542 #endif
 543
 544 #ifdef CONFIG_LOCKDEP
 545 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
 546 #else
 547 static inline void
 548 lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 549 {
 550 }
 551 #endif
 552
 553 #endif /* __LINUX_LOCKDEP_H */