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 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         u8                              irq_context;
 200         u8                              depth;
 201         u16                             base;
 202         struct list_head                entry;
 203         u64                             chain_key;
 204 };
 205
 206 #define MAX_LOCKDEP_KEYS_BITS           13
 207 /*
 208  * Subtract one because we offset hlock->class_idx by 1 in order
 209  * to make 0 mean no class. This avoids overflowing the class_idx
 210  * bitfield and hitting the BUG in hlock_class().
 211  */
 212 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 213
 214 struct held_lock {
 215         /*
 216          * One-way hash of the dependency chain up to this point. We
 217          * hash the hashes step by step as the dependency chain grows.
 218          *
 219          * We use it for dependency-caching and we skip detection
 220          * passes and dependency-updates if there is a cache-hit, so
 221          * it is absolutely critical for 100% coverage of the validator
 222          * to have a unique key value for every unique dependency path
 223          * that can occur in the system, to make a unique hash value
 224          * as likely as possible - hence the 64-bit width.
 225          *
 226          * The task struct holds the current hash value (initialized
 227          * with zero), here we store the previous hash value:
 228          */
 229         u64                             prev_chain_key;
 230         unsigned long                   acquire_ip;
 231         struct lockdep_map              *instance;
 232         struct lockdep_map              *nest_lock;
 233 #ifdef CONFIG_LOCK_STAT
 234         u64                             waittime_stamp;
 235         u64                             holdtime_stamp;
 236 #endif
 237         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 238         /*
 239          * The lock-stack is unified in that the lock chains of interrupt
 240          * contexts nest ontop of process context chains, but we 'separate'
 241          * the hashes by starting with 0 if we cross into an interrupt
 242          * context, and we also keep do not add cross-context lock
 243          * dependencies - the lock usage graph walking covers that area
 244          * anyway, and we'd just unnecessarily increase the number of
 245          * dependencies otherwise. [Note: hardirq and softirq contexts
 246          * are separated from each other too.]
 247          *
 248          * The following field is used to detect when we cross into an
 249          * interrupt context:
 250          */
 251         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 252         unsigned int trylock:1;                                         /* 16 bits */
 253
 254         unsigned int read:2;        /* see lock_acquire() comment */
 255         unsigned int check:2;       /* see lock_acquire() comment */
 256         unsigned int hardirqs_off:1;
 257         unsigned int references:11;                                     /* 32 bits */
 258 };
 259
 260 /*
 261  * Initialization, self-test and debugging-output methods:
 262  */
 263 extern void lockdep_init(void);
 264 extern void lockdep_info(void);
 265 extern void lockdep_reset(void);
 266 extern void lockdep_reset_lock(struct lockdep_map *lock);
 267 extern void lockdep_free_key_range(void *start, unsigned long size);
 268 extern void lockdep_sys_exit(void);
 269
 270 extern void lockdep_off(void);
 271 extern void lockdep_on(void);
 272
 273 /*
 274  * These methods are used by specific locking variants (spinlocks,
 275  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 276  * to lockdep:
 277  */
 278
 279 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 280                              struct lock_class_key *key, int subclass);
 281
 282 /*
 283  * To initialize a lockdep_map statically use this macro.
 284  * Note that _name must not be NULL.
 285  */
 286 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 287         { .name = (_name), .key = (void *)(_key), }
 288
 289 /*
 290  * Reinitialize a lock key - for cases where there is special locking or
 291  * special initialization of locks so that the validator gets the scope
 292  * of dependencies wrong: they are either too broad (they need a class-split)
 293  * or they are too narrow (they suffer from a false class-split):
 294  */
 295 #define lockdep_set_class(lock, key) \
 296                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 297 #define lockdep_set_class_and_name(lock, key, name) \
 298                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 299 #define lockdep_set_class_and_subclass(lock, key, sub) \
 300                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 301 #define lockdep_set_subclass(lock, sub) \
 302                 lockdep_init_map(&(lock)->dep_map, #lock, \
 303                                  (lock)->dep_map.key, sub)
 304
 305 #define lockdep_set_novalidate_class(lock) \
 306         lockdep_set_class(lock, &__lockdep_no_validate__)
 307 /*
 308  * Compare locking classes
 309  */
 310 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
 311
 312 static inline int lockdep_match_key(struct lockdep_map *lock,
 313                                     struct lock_class_key *key)
 314 {
 315         return lock->key == key;
 316 }
 317
 318 /*
 319  * Acquire a lock.
 320  *
 321  * Values for "read":
 322  *
 323  *   0: exclusive (write) acquire
 324  *   1: read-acquire (no recursion allowed)
 325  *   2: read-acquire with same-instance recursion allowed
 326  *
 327  * Values for check:
 328  *
 329  *   0: disabled
 330  *   1: simple checks (freeing, held-at-exit-time, etc.)
 331  *   2: full validation
 332  */
 333 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 334                          int trylock, int read, int check,
 335                          struct lockdep_map *nest_lock, unsigned long ip);
 336
 337 extern void lock_release(struct lockdep_map *lock, int nested,
 338                          unsigned long ip);
 339
 340 #define lockdep_is_held(lock)   lock_is_held(&(lock)->dep_map)
 341
 342 extern int lock_is_held(struct lockdep_map *lock);
 343
 344 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 345                            struct lock_class_key *key, unsigned int subclass,
 346                            unsigned long ip);
 347
 348 static inline void lock_set_subclass(struct lockdep_map *lock,
 349                 unsigned int subclass, unsigned long ip)
 350 {
 351         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 352 }
 353
 354 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 355 extern void lockdep_clear_current_reclaim_state(void);
 356 extern void lockdep_trace_alloc(gfp_t mask);
 357
 358 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 359
 360 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 361
 362 #define lockdep_assert_held(l)  do {                            \
 363                 WARN_ON(debug_locks && !lockdep_is_held(l));    \
 364         } while (0)
 365
 366 #define lockdep_recursing(tsk)  ((tsk)->lockdep_recursion)
 367
 368 #else /* !CONFIG_LOCKDEP */
 369
 370 static inline void lockdep_off(void)
 371 {
 372 }
 373
 374 static inline void lockdep_on(void)
 375 {
 376 }
 377
 378 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 379 # define lock_release(l, n, i)                  do { } while (0)
 380 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 381 # define lock_set_subclass(l, s, i)             do { } while (0)
 382 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 383 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 384 # define lockdep_trace_alloc(g)                 do { } while (0)
 385 # define lockdep_init()                         do { } while (0)
 386 # define lockdep_info()                         do { } while (0)
 387 # define lockdep_init_map(lock, name, key, sub) \
 388                 do { (void)(name); (void)(key); } while (0)
 389 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 390 # define lockdep_set_class_and_name(lock, key, name) \
 391                 do { (void)(key); (void)(name); } while (0)
 392 #define lockdep_set_class_and_subclass(lock, key, sub) \
 393                 do { (void)(key); } while (0)
 394 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 395
 396 #define lockdep_set_novalidate_class(lock) do { } while (0)
 397
 398 /*
 399  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
 400  * case since the result is not well defined and the caller should rather
 401  * #ifdef the call himself.
 402  */
 403
 404 # define INIT_LOCKDEP
 405 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 406 # define lockdep_free_key_range(start, size)    do { } while (0)
 407 # define lockdep_sys_exit()                     do { } while (0)
 408 /*
 409  * The class key takes no space if lockdep is disabled:
 410  */
 411 struct lock_class_key { };
 412
 413 #define lockdep_depth(tsk)      (0)
 414
 415 #define lockdep_assert_held(l)                  do { (void)(l); } while (0)
 416
 417 #define lockdep_recursing(tsk)                  (0)
 418
 419 #endif /* !LOCKDEP */
 420
 421 #ifdef CONFIG_LOCK_STAT
 422
 423 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 424 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 425
 426 #define LOCK_CONTENDED(_lock, try, lock)                        \
 427 do {                                                            \
 428         if (!try(_lock)) {                                      \
 429                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 430                 lock(_lock);                                    \
 431         }                                                       \
 432         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 433 } while (0)
 434
 435 #else /* CONFIG_LOCK_STAT */
 436
 437 #define lock_contended(lockdep_map, ip) do {} while (0)
 438 #define lock_acquired(lockdep_map, ip) do {} while (0)
 439
 440 #define LOCK_CONTENDED(_lock, try, lock) \
 441         lock(_lock)
 442
 443 #endif /* CONFIG_LOCK_STAT */
 444
 445 #ifdef CONFIG_LOCKDEP
 446
 447 /*
 448  * On lockdep we dont want the hand-coded irq-enable of
 449  * _raw_*_lock_flags() code, because lockdep assumes
 450  * that interrupts are not re-enabled during lock-acquire:
 451  */
 452 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 453         LOCK_CONTENDED((_lock), (try), (lock))
 454
 455 #else /* CONFIG_LOCKDEP */
 456
 457 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 458         lockfl((_lock), (flags))
 459
 460 #endif /* CONFIG_LOCKDEP */
 461
 462 #ifdef CONFIG_TRACE_IRQFLAGS
 463 extern void print_irqtrace_events(struct task_struct *curr);
 464 #else
 465 static inline void print_irqtrace_events(struct task_struct *curr)
 466 {
 467 }
 468 #endif
 469
 470 /*
 471  * For trivial one-depth nesting of a lock-class, the following
 472  * global define can be used. (Subsystems with multiple levels
 473  * of nesting should define their own lock-nesting subclasses.)
 474  */
 475 #define SINGLE_DEPTH_NESTING                    1
 476
 477 /*
 478  * Map the dependency ops to NOP or to real lockdep ops, depending
 479  * on the per lock-class debug mode:
 480  */
 481
 482 #ifdef CONFIG_PROVE_LOCKING
 483  #define lock_acquire_exclusive(l, s, t, n, i)          lock_acquire(l, s, t, 0, 2, n, i)
 484  #define lock_acquire_shared(l, s, t, n, i)             lock_acquire(l, s, t, 1, 2, n, i)
 485  #define lock_acquire_shared_recursive(l, s, t, n, i)   lock_acquire(l, s, t, 2, 2, n, i)
 486 #else
 487  #define lock_acquire_exclusive(l, s, t, n, i)          lock_acquire(l, s, t, 0, 1, n, i)
 488  #define lock_acquire_shared(l, s, t, n, i)             lock_acquire(l, s, t, 1, 1, n, i)
 489  #define lock_acquire_shared_recursive(l, s, t, n, i)   lock_acquire(l, s, t, 2, 1, n, i)
 490 #endif
 491
 492 #define spin_acquire(l, s, t, i)                lock_acquire_exclusive(l, s, t, NULL, i)
 493 #define spin_acquire_nest(l, s, t, n, i)        lock_acquire_exclusive(l, s, t, n, i)
 494 #define spin_release(l, n, i)                   lock_release(l, n, i)
 495
 496 #define rwlock_acquire(l, s, t, i)              lock_acquire_exclusive(l, s, t, NULL, i)
 497 #define rwlock_acquire_read(l, s, t, i)         lock_acquire_shared_recursive(l, s, t, NULL, i)
 498 #define rwlock_release(l, n, i)                 lock_release(l, n, i)
 499
 500 #define seqcount_acquire(l, s, t, i)            lock_acquire_exclusive(l, s, t, NULL, i)
 501 #define seqcount_acquire_read(l, s, t, i)       lock_acquire_shared_recursive(l, s, t, NULL, i)
 502 #define seqcount_release(l, n, i)               lock_release(l, n, i)
 503
 504 #define mutex_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
 505 #define mutex_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
 506 #define mutex_release(l, n, i)                  lock_release(l, n, i)
 507
 508 #define rwsem_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
 509 #define rwsem_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
 510 #define rwsem_acquire_read(l, s, t, i)          lock_acquire_shared(l, s, t, NULL, i)
 511 #define rwsem_release(l, n, i)                  lock_release(l, n, i)
 512
 513 #define lock_map_acquire(l)                     lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
 514 #define lock_map_acquire_read(l)                lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
 515 #define lock_map_release(l)                     lock_release(l, 1, _THIS_IP_)
 516
 517 #ifdef CONFIG_PROVE_LOCKING
 518 # define might_lock(lock)                                               \
 519 do {                                                                    \
 520         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 521         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 522         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 523 } while (0)
 524 # define might_lock_read(lock)                                          \
 525 do {                                                                    \
 526         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 527         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 528         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 529 } while (0)
 530 #else
 531 # define might_lock(lock) do { } while (0)
 532 # define might_lock_read(lock) do { } while (0)
 533 #endif
 534
 535 #ifdef CONFIG_PROVE_RCU
 536 void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
 537 #endif
 538
 539 #endif /* __LINUX_LOCKDEP_H */