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  * Lock-class usage-state bits:
  24  */
  25 enum lock_usage_bit
  26 {
  27         LOCK_USED = 0,
  28         LOCK_USED_IN_HARDIRQ,
  29         LOCK_USED_IN_SOFTIRQ,
  30         LOCK_USED_IN_RECLAIM_FS,
  31         LOCK_ENABLED_SOFTIRQS,
  32         LOCK_ENABLED_HARDIRQS,
  33         LOCK_HELD_OVER_RECLAIM_FS,
  34         LOCK_USED_IN_HARDIRQ_READ,
  35         LOCK_USED_IN_SOFTIRQ_READ,
  36         LOCK_USED_IN_RECLAIM_FS_READ,
  37         LOCK_ENABLED_SOFTIRQS_READ,
  38         LOCK_ENABLED_HARDIRQS_READ,
  39         LOCK_HELD_OVER_RECLAIM_FS_READ,
  40         LOCK_USAGE_STATES
  41 };
  42
  43 /*
  44  * Usage-state bitmasks:
  45  */
  46 #define LOCKF_USED                      (1 << LOCK_USED)
  47 #define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
  48 #define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
  49 #define LOCKF_USED_IN_RECLAIM_FS        (1 << LOCK_USED_IN_RECLAIM_FS)
  50 #define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
  51 #define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)
  52 #define LOCKF_HELD_OVER_RECLAIM_FS      (1 << LOCK_HELD_OVER_RECLAIM_FS)
  53
  54 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
  55 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
  56
  57 #define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
  58 #define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
  59 #define LOCKF_USED_IN_RECLAIM_FS_READ   (1 << LOCK_USED_IN_RECLAIM_FS_READ)
  60 #define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
  61 #define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)
  62 #define LOCKF_HELD_OVER_RECLAIM_FS_READ (1 << LOCK_HELD_OVER_RECLAIM_FS_READ)
  63
  64 #define LOCKF_ENABLED_IRQS_READ \
  65                 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
  66 #define LOCKF_USED_IN_IRQ_READ \
  67                 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
  68
  69 #define MAX_LOCKDEP_SUBCLASSES          8UL
  70
  71 /*
  72  * Lock-classes are keyed via unique addresses, by embedding the
  73  * lockclass-key into the kernel (or module) .data section. (For
  74  * static locks we use the lock address itself as the key.)
  75  */
  76 struct lockdep_subclass_key {
  77         char __one_byte;
  78 } __attribute__ ((__packed__));
  79
  80 struct lock_class_key {
  81         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  82 };
  83
  84 #define LOCKSTAT_POINTS         4
  85
  86 /*
  87  * The lock-class itself:
  88  */
  89 struct lock_class {
  90         /*
  91          * class-hash:
  92          */
  93         struct list_head                hash_entry;
  94
  95         /*
  96          * global list of all lock-classes:
  97          */
  98         struct list_head                lock_entry;
  99
 100         struct lockdep_subclass_key     *key;
 101         unsigned int                    subclass;
 102         unsigned int                    dep_gen_id;
 103
 104         /*
 105          * IRQ/softirq usage tracking bits:
 106          */
 107         unsigned long                   usage_mask;
 108         struct stack_trace              usage_traces[LOCK_USAGE_STATES];
 109
 110         /*
 111          * These fields represent a directed graph of lock dependencies,
 112          * to every node we attach a list of "forward" and a list of
 113          * "backward" graph nodes.
 114          */
 115         struct list_head                locks_after, locks_before;
 116
 117         /*
 118          * Generation counter, when doing certain classes of graph walking,
 119          * to ensure that we check one node only once:
 120          */
 121         unsigned int                    version;
 122
 123         /*
 124          * Statistics counter:
 125          */
 126         unsigned long                   ops;
 127
 128         const char                      *name;
 129         int                             name_version;
 130
 131 #ifdef CONFIG_LOCK_STAT
 132         unsigned long                   contention_point[LOCKSTAT_POINTS];
 133         unsigned long                   contending_point[LOCKSTAT_POINTS];
 134 #endif
 135 };
 136
 137 #ifdef CONFIG_LOCK_STAT
 138 struct lock_time {
 139         s64                             min;
 140         s64                             max;
 141         s64                             total;
 142         unsigned long                   nr;
 143 };
 144
 145 enum bounce_type {
 146         bounce_acquired_write,
 147         bounce_acquired_read,
 148         bounce_contended_write,
 149         bounce_contended_read,
 150         nr_bounce_types,
 151
 152         bounce_acquired = bounce_acquired_write,
 153         bounce_contended = bounce_contended_write,
 154 };
 155
 156 struct lock_class_stats {
 157         unsigned long                   contention_point[4];
 158         unsigned long                   contending_point[4];
 159         struct lock_time                read_waittime;
 160         struct lock_time                write_waittime;
 161         struct lock_time                read_holdtime;
 162         struct lock_time                write_holdtime;
 163         unsigned long                   bounces[nr_bounce_types];
 164 };
 165
 166 struct lock_class_stats lock_stats(struct lock_class *class);
 167 void clear_lock_stats(struct lock_class *class);
 168 #endif
 169
 170 /*
 171  * Map the lock object (the lock instance) to the lock-class object.
 172  * This is embedded into specific lock instances:
 173  */
 174 struct lockdep_map {
 175         struct lock_class_key           *key;
 176         struct lock_class               *class_cache;
 177         const char                      *name;
 178 #ifdef CONFIG_LOCK_STAT
 179         int                             cpu;
 180         unsigned long                   ip;
 181 #endif
 182 };
 183
 184 /*
 185  * Every lock has a list of other locks that were taken after it.
 186  * We only grow the list, never remove from it:
 187  */
 188 struct lock_list {
 189         struct list_head                entry;
 190         struct lock_class               *class;
 191         struct stack_trace              trace;
 192         int                             distance;
 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;
 253         unsigned int read:2;        /* see lock_acquire() comment */
 254         unsigned int check:2;       /* see lock_acquire() comment */
 255         unsigned int hardirqs_off:1;
 256 };
 257
 258 /*
 259  * Initialization, self-test and debugging-output methods:
 260  */
 261 extern void lockdep_init(void);
 262 extern void lockdep_info(void);
 263 extern void lockdep_reset(void);
 264 extern void lockdep_reset_lock(struct lockdep_map *lock);
 265 extern void lockdep_free_key_range(void *start, unsigned long size);
 266 extern void lockdep_sys_exit(void);
 267
 268 extern void lockdep_off(void);
 269 extern void lockdep_on(void);
 270
 271 /*
 272  * These methods are used by specific locking variants (spinlocks,
 273  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 274  * to lockdep:
 275  */
 276
 277 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 278                              struct lock_class_key *key, int subclass);
 279
 280 /*
 281  * To initialize a lockdep_map statically use this macro.
 282  * Note that _name must not be NULL.
 283  */
 284 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 285         { .name = (_name), .key = (void *)(_key), }
 286
 287 /*
 288  * Reinitialize a lock key - for cases where there is special locking or
 289  * special initialization of locks so that the validator gets the scope
 290  * of dependencies wrong: they are either too broad (they need a class-split)
 291  * or they are too narrow (they suffer from a false class-split):
 292  */
 293 #define lockdep_set_class(lock, key) \
 294                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 295 #define lockdep_set_class_and_name(lock, key, name) \
 296                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 297 #define lockdep_set_class_and_subclass(lock, key, sub) \
 298                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 299 #define lockdep_set_subclass(lock, sub) \
 300                 lockdep_init_map(&(lock)->dep_map, #lock, \
 301                                  (lock)->dep_map.key, sub)
 302
 303 /*
 304  * Acquire a lock.
 305  *
 306  * Values for "read":
 307  *
 308  *   0: exclusive (write) acquire
 309  *   1: read-acquire (no recursion allowed)
 310  *   2: read-acquire with same-instance recursion allowed
 311  *
 312  * Values for check:
 313  *
 314  *   0: disabled
 315  *   1: simple checks (freeing, held-at-exit-time, etc.)
 316  *   2: full validation
 317  */
 318 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 319                          int trylock, int read, int check,
 320                          struct lockdep_map *nest_lock, unsigned long ip);
 321
 322 extern void lock_release(struct lockdep_map *lock, int nested,
 323                          unsigned long ip);
 324
 325 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 326                            struct lock_class_key *key, unsigned int subclass,
 327                            unsigned long ip);
 328
 329 static inline void lock_set_subclass(struct lockdep_map *lock,
 330                 unsigned int subclass, unsigned long ip)
 331 {
 332         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 333 }
 334
 335 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 336 extern void lockdep_clear_current_reclaim_state(void);
 337 extern void lockdep_trace_alloc(gfp_t mask);
 338
 339 # define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 340
 341 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 342
 343 #else /* !LOCKDEP */
 344
 345 static inline void lockdep_off(void)
 346 {
 347 }
 348
 349 static inline void lockdep_on(void)
 350 {
 351 }
 352
 353 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 354 # define lock_release(l, n, i)                  do { } while (0)
 355 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 356 # define lock_set_subclass(l, s, i)             do { } while (0)
 357 # define lockdep_set_current_reclaim_state(g)   do { } while (0)
 358 # define lockdep_clear_current_reclaim_state()  do { } while (0)
 359 # define lockdep_trace_alloc(g)                 do { } while (0)
 360 # define lockdep_init()                         do { } while (0)
 361 # define lockdep_info()                         do { } while (0)
 362 # define lockdep_init_map(lock, name, key, sub) \
 363                 do { (void)(name); (void)(key); } while (0)
 364 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 365 # define lockdep_set_class_and_name(lock, key, name) \
 366                 do { (void)(key); (void)(name); } while (0)
 367 #define lockdep_set_class_and_subclass(lock, key, sub) \
 368                 do { (void)(key); } while (0)
 369 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 370
 371 # define INIT_LOCKDEP
 372 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 373 # define lockdep_free_key_range(start, size)    do { } while (0)
 374 # define lockdep_sys_exit()                     do { } while (0)
 375 /*
 376  * The class key takes no space if lockdep is disabled:
 377  */
 378 struct lock_class_key { };
 379
 380 #define lockdep_depth(tsk)      (0)
 381
 382 #endif /* !LOCKDEP */
 383
 384 #ifdef CONFIG_LOCK_STAT
 385
 386 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 387 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 388
 389 #define LOCK_CONTENDED(_lock, try, lock)                        \
 390 do {                                                            \
 391         if (!try(_lock)) {                                      \
 392                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 393                 lock(_lock);                                    \
 394         }                                                       \
 395         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 396 } while (0)
 397
 398 #else /* CONFIG_LOCK_STAT */
 399
 400 #define lock_contended(lockdep_map, ip) do {} while (0)
 401 #define lock_acquired(lockdep_map, ip) do {} while (0)
 402
 403 #define LOCK_CONTENDED(_lock, try, lock) \
 404         lock(_lock)
 405
 406 #endif /* CONFIG_LOCK_STAT */
 407
 408 #ifdef CONFIG_GENERIC_HARDIRQS
 409 extern void early_init_irq_lock_class(void);
 410 #else
 411 static inline void early_init_irq_lock_class(void)
 412 {
 413 }
 414 #endif
 415
 416 #ifdef CONFIG_TRACE_IRQFLAGS
 417 extern void early_boot_irqs_off(void);
 418 extern void early_boot_irqs_on(void);
 419 extern void print_irqtrace_events(struct task_struct *curr);
 420 #else
 421 static inline void early_boot_irqs_off(void)
 422 {
 423 }
 424 static inline void early_boot_irqs_on(void)
 425 {
 426 }
 427 static inline void print_irqtrace_events(struct task_struct *curr)
 428 {
 429 }
 430 #endif
 431
 432 /*
 433  * For trivial one-depth nesting of a lock-class, the following
 434  * global define can be used. (Subsystems with multiple levels
 435  * of nesting should define their own lock-nesting subclasses.)
 436  */
 437 #define SINGLE_DEPTH_NESTING                    1
 438
 439 /*
 440  * Map the dependency ops to NOP or to real lockdep ops, depending
 441  * on the per lock-class debug mode:
 442  */
 443
 444 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 445 # ifdef CONFIG_PROVE_LOCKING
 446 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 447 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 448 # else
 449 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 450 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 451 # endif
 452 # define spin_release(l, n, i)                  lock_release(l, n, i)
 453 #else
 454 # define spin_acquire(l, s, t, i)               do { } while (0)
 455 # define spin_release(l, n, i)                  do { } while (0)
 456 #endif
 457
 458 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 459 # ifdef CONFIG_PROVE_LOCKING
 460 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 461 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 462 # else
 463 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 464 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 465 # endif
 466 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 467 #else
 468 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 469 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 470 # define rwlock_release(l, n, i)                do { } while (0)
 471 #endif
 472
 473 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 474 # ifdef CONFIG_PROVE_LOCKING
 475 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 476 # else
 477 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 478 # endif
 479 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 480 #else
 481 # define mutex_acquire(l, s, t, i)              do { } while (0)
 482 # define mutex_release(l, n, i)                 do { } while (0)
 483 #endif
 484
 485 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 486 # ifdef CONFIG_PROVE_LOCKING
 487 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 488 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 489 # else
 490 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 491 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 492 # endif
 493 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 494 #else
 495 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 496 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 497 # define rwsem_release(l, n, i)                 do { } while (0)
 498 #endif
 499
 500 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 501 # ifdef CONFIG_PROVE_LOCKING
 502 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 503 # else
 504 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 505 # endif
 506 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 507 #else
 508 # define lock_map_acquire(l)                    do { } while (0)
 509 # define lock_map_release(l)                    do { } while (0)
 510 #endif
 511
 512 #ifdef CONFIG_PROVE_LOCKING
 513 # define might_lock(lock)                                               \
 514 do {                                                                    \
 515         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 516         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 517         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 518 } while (0)
 519 # define might_lock_read(lock)                                          \
 520 do {                                                                    \
 521         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 522         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 523         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 524 } while (0)
 525 #else
 526 # define might_lock(lock) do { } while (0)
 527 # define might_lock_read(lock) do { } while (0)
 528 #endif
 529
 530 #endif /* __LINUX_LOCKDEP_H */