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 /*
 155  * We record lock dependency chains, so that we can cache them:
 156  */
 157 struct lock_chain {
 158         u8                              irq_context;
 159         u8                              depth;
 160         u16                             base;
 161         struct list_head                entry;
 162         u64                             chain_key;
 163 };
 164
 165 #define MAX_LOCKDEP_KEYS_BITS           13
 166 /*
 167  * Subtract one because we offset hlock->class_idx by 1 in order
 168  * to make 0 mean no class. This avoids overflowing the class_idx
 169  * bitfield and hitting the BUG in hlock_class().
 170  */
 171 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 172
 173 struct held_lock {
 174         /*
 175          * One-way hash of the dependency chain up to this point. We
 176          * hash the hashes step by step as the dependency chain grows.
 177          *
 178          * We use it for dependency-caching and we skip detection
 179          * passes and dependency-updates if there is a cache-hit, so
 180          * it is absolutely critical for 100% coverage of the validator
 181          * to have a unique key value for every unique dependency path
 182          * that can occur in the system, to make a unique hash value
 183          * as likely as possible - hence the 64-bit width.
 184          *
 185          * The task struct holds the current hash value (initialized
 186          * with zero), here we store the previous hash value:
 187          */
 188         u64                             prev_chain_key;
 189         unsigned long                   acquire_ip;
 190         struct lockdep_map              *instance;
 191         struct lockdep_map              *nest_lock;
 192 #ifdef CONFIG_LOCK_STAT
 193         u64                             waittime_stamp;
 194         u64                             holdtime_stamp;
 195 #endif
 196         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 197         /*
 198          * The lock-stack is unified in that the lock chains of interrupt
 199          * contexts nest ontop of process context chains, but we 'separate'
 200          * the hashes by starting with 0 if we cross into an interrupt
 201          * context, and we also keep do not add cross-context lock
 202          * dependencies - the lock usage graph walking covers that area
 203          * anyway, and we'd just unnecessarily increase the number of
 204          * dependencies otherwise. [Note: hardirq and softirq contexts
 205          * are separated from each other too.]
 206          *
 207          * The following field is used to detect when we cross into an
 208          * interrupt context:
 209          */
 210         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 211         unsigned int trylock:1;
 212         unsigned int read:2;        /* see lock_acquire() comment */
 213         unsigned int check:2;       /* see lock_acquire() comment */
 214         unsigned int hardirqs_off:1;
 215 };
 216
 217 /*
 218  * Initialization, self-test and debugging-output methods:
 219  */
 220 extern void lockdep_init(void);
 221 extern void lockdep_info(void);
 222 extern void lockdep_reset(void);
 223 extern void lockdep_reset_lock(struct lockdep_map *lock);
 224 extern void lockdep_free_key_range(void *start, unsigned long size);
 225 extern void lockdep_sys_exit(void);
 226
 227 extern void lockdep_off(void);
 228 extern void lockdep_on(void);
 229
 230 /*
 231  * These methods are used by specific locking variants (spinlocks,
 232  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 233  * to lockdep:
 234  */
 235
 236 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 237                              struct lock_class_key *key, int subclass);
 238
 239 /*
 240  * To initialize a lockdep_map statically use this macro.
 241  * Note that _name must not be NULL.
 242  */
 243 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 244         { .name = (_name), .key = (void *)(_key), }
 245
 246 /*
 247  * Reinitialize a lock key - for cases where there is special locking or
 248  * special initialization of locks so that the validator gets the scope
 249  * of dependencies wrong: they are either too broad (they need a class-split)
 250  * or they are too narrow (they suffer from a false class-split):
 251  */
 252 #define lockdep_set_class(lock, key) \
 253                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 254 #define lockdep_set_class_and_name(lock, key, name) \
 255                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 256 #define lockdep_set_class_and_subclass(lock, key, sub) \
 257                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 258 #define lockdep_set_subclass(lock, sub) \
 259                 lockdep_init_map(&(lock)->dep_map, #lock, \
 260                                  (lock)->dep_map.key, sub)
 261
 262 /*
 263  * Acquire a lock.
 264  *
 265  * Values for "read":
 266  *
 267  *   0: exclusive (write) acquire
 268  *   1: read-acquire (no recursion allowed)
 269  *   2: read-acquire with same-instance recursion allowed
 270  *
 271  * Values for check:
 272  *
 273  *   0: disabled
 274  *   1: simple checks (freeing, held-at-exit-time, etc.)
 275  *   2: full validation
 276  */
 277 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 278                          int trylock, int read, int check,
 279                          struct lockdep_map *nest_lock, unsigned long ip);
 280
 281 extern void lock_release(struct lockdep_map *lock, int nested,
 282                          unsigned long ip);
 283
 284 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 285                            struct lock_class_key *key, unsigned int subclass,
 286                            unsigned long ip);
 287
 288 static inline void lock_set_subclass(struct lockdep_map *lock,
 289                 unsigned int subclass, unsigned long ip)
 290 {
 291         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 292 }
 293
 294 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 295 extern void lockdep_clear_current_reclaim_state(void);
 296 extern void lockdep_trace_alloc(gfp_t mask);
 297
 298 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 299
 300 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 301
 302 #else /* !LOCKDEP */
 303
 304 static inline void lockdep_off(void)
 305 {
 306 }
 307
 308 static inline void lockdep_on(void)
 309 {
 310 }
 311
 312 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 313 # define lock_release(l, n, i)                  do { } while (0)
 314 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 315 # define lock_set_subclass(l, s, i)             do { } while (0)
 316 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 317 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 318 # define lockdep_trace_alloc(g)                 do { } while (0)
 319 # define lockdep_init()                         do { } while (0)
 320 # define lockdep_info()                         do { } while (0)
 321 # define lockdep_init_map(lock, name, key, sub) \
 322                 do { (void)(name); (void)(key); } while (0)
 323 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 324 # define lockdep_set_class_and_name(lock, key, name) \
 325                 do { (void)(key); (void)(name); } while (0)
 326 #define lockdep_set_class_and_subclass(lock, key, sub) \
 327                 do { (void)(key); } while (0)
 328 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 329
 330 # define INIT_LOCKDEP
 331 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 332 # define lockdep_free_key_range(start, size)    do { } while (0)
 333 # define lockdep_sys_exit()                     do { } while (0)
 334 /*
 335  * The class key takes no space if lockdep is disabled:
 336  */
 337 struct lock_class_key { };
 338
 339 #define lockdep_depth(tsk)      (0)
 340
 341 #endif /* !LOCKDEP */
 342
 343 #ifdef CONFIG_LOCK_STAT
 344
 345 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 346 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 347
 348 #define LOCK_CONTENDED(_lock, try, lock)                        \
 349 do {                                                            \
 350         if (!try(_lock)) {                                      \
 351                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 352                 lock(_lock);                                    \
 353         }                                                       \
 354         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 355 } while (0)
 356
 357 #else /* CONFIG_LOCK_STAT */
 358
 359 #define lock_contended(lockdep_map, ip) do {} while (0)
 360 #define lock_acquired(lockdep_map, ip) do {} while (0)
 361
 362 #define LOCK_CONTENDED(_lock, try, lock) \
 363         lock(_lock)
 364
 365 #endif /* CONFIG_LOCK_STAT */
 366
 367 #ifdef CONFIG_LOCKDEP
 368
 369 /*
 370  * On lockdep we dont want the hand-coded irq-enable of
 371  * _raw_*_lock_flags() code, because lockdep assumes
 372  * that interrupts are not re-enabled during lock-acquire:
 373  */
 374 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 375         LOCK_CONTENDED((_lock), (try), (lock))
 376
 377 #else /* CONFIG_LOCKDEP */
 378
 379 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 380         lockfl((_lock), (flags))
 381
 382 #endif /* CONFIG_LOCKDEP */
 383
 384 #ifdef CONFIG_GENERIC_HARDIRQS
 385 extern void early_init_irq_lock_class(void);
 386 #else
 387 static inline void early_init_irq_lock_class(void)
 388 {
 389 }
 390 #endif
 391
 392 #ifdef CONFIG_TRACE_IRQFLAGS
 393 extern void early_boot_irqs_off(void);
 394 extern void early_boot_irqs_on(void);
 395 extern void print_irqtrace_events(struct task_struct *curr);
 396 #else
 397 static inline void early_boot_irqs_off(void)
 398 {
 399 }
 400 static inline void early_boot_irqs_on(void)
 401 {
 402 }
 403 static inline void print_irqtrace_events(struct task_struct *curr)
 404 {
 405 }
 406 #endif
 407
 408 /*
 409  * For trivial one-depth nesting of a lock-class, the following
 410  * global define can be used. (Subsystems with multiple levels
 411  * of nesting should define their own lock-nesting subclasses.)
 412  */
 413 #define SINGLE_DEPTH_NESTING                    1
 414
 415 /*
 416  * Map the dependency ops to NOP or to real lockdep ops, depending
 417  * on the per lock-class debug mode:
 418  */
 419
 420 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 421 # ifdef CONFIG_PROVE_LOCKING
 422 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 423 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 424 # else
 425 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 426 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 427 # endif
 428 # define spin_release(l, n, i)                  lock_release(l, n, i)
 429 #else
 430 # define spin_acquire(l, s, t, i)               do { } while (0)
 431 # define spin_release(l, n, i)                  do { } while (0)
 432 #endif
 433
 434 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 435 # ifdef CONFIG_PROVE_LOCKING
 436 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 437 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 438 # else
 439 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 440 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 441 # endif
 442 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 443 #else
 444 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 445 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 446 # define rwlock_release(l, n, i)                do { } while (0)
 447 #endif
 448
 449 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 450 # ifdef CONFIG_PROVE_LOCKING
 451 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 452 # else
 453 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 454 # endif
 455 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 456 #else
 457 # define mutex_acquire(l, s, t, i)              do { } while (0)
 458 # define mutex_release(l, n, i)                 do { } while (0)
 459 #endif
 460
 461 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 462 # ifdef CONFIG_PROVE_LOCKING
 463 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 464 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 465 # else
 466 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 467 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 468 # endif
 469 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 470 #else
 471 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 472 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 473 # define rwsem_release(l, n, i)                 do { } while (0)
 474 #endif
 475
 476 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 477 # ifdef CONFIG_PROVE_LOCKING
 478 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 479 # else
 480 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 481 # endif
 482 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 483 #else
 484 # define lock_map_acquire(l)                    do { } while (0)
 485 # define lock_map_release(l)                    do { } while (0)
 486 #endif
 487
 488 #ifdef CONFIG_PROVE_LOCKING
 489 # define might_lock(lock)                                               \
 490 do {                                                                    \
 491         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 492         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 493         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 494 } while (0)
 495 # define might_lock_read(lock)                                          \
 496 do {                                                                    \
 497         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 498         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 499         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 500 } while (0)
 501 #else
 502 # define might_lock(lock) do { } while (0)
 503 # define might_lock_read(lock) do { } while (0)
 504 #endif
 505
 506 #endif /* __LINUX_LOCKDEP_H */