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_ENABLED_SOFTIRQS,
  31         LOCK_ENABLED_HARDIRQS,
  32         LOCK_USED_IN_HARDIRQ_READ,
  33         LOCK_USED_IN_SOFTIRQ_READ,
  34         LOCK_ENABLED_SOFTIRQS_READ,
  35         LOCK_ENABLED_HARDIRQS_READ,
  36         LOCK_USAGE_STATES
  37 };
  38
  39 /*
  40  * Usage-state bitmasks:
  41  */
  42 #define LOCKF_USED                      (1 << LOCK_USED)
  43 #define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
  44 #define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
  45 #define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
  46 #define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)
  47
  48 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
  49 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
  50
  51 #define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
  52 #define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
  53 #define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
  54 #define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)
  55
  56 #define LOCKF_ENABLED_IRQS_READ \
  57                 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
  58 #define LOCKF_USED_IN_IRQ_READ \
  59                 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
  60
  61 #define MAX_LOCKDEP_SUBCLASSES          8UL
  62
  63 /*
  64  * Lock-classes are keyed via unique addresses, by embedding the
  65  * lockclass-key into the kernel (or module) .data section. (For
  66  * static locks we use the lock address itself as the key.)
  67  */
  68 struct lockdep_subclass_key {
  69         char __one_byte;
  70 } __attribute__ ((__packed__));
  71
  72 struct lock_class_key {
  73         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  74 };
  75
  76 #define LOCKSTAT_POINTS         4
  77
  78 /*
  79  * The lock-class itself:
  80  */
  81 struct lock_class {
  82         /*
  83          * class-hash:
  84          */
  85         struct list_head                hash_entry;
  86
  87         /*
  88          * global list of all lock-classes:
  89          */
  90         struct list_head                lock_entry;
  91
  92         struct lockdep_subclass_key     *key;
  93         unsigned int                    subclass;
  94         unsigned int                    dep_gen_id;
  95
  96         /*
  97          * IRQ/softirq usage tracking bits:
  98          */
  99         unsigned long                   usage_mask;
 100         struct stack_trace              usage_traces[LOCK_USAGE_STATES];
 101
 102         /*
 103          * These fields represent a directed graph of lock dependencies,
 104          * to every node we attach a list of "forward" and a list of
 105          * "backward" graph nodes.
 106          */
 107         struct list_head                locks_after, locks_before;
 108
 109         /*
 110          * Generation counter, when doing certain classes of graph walking,
 111          * to ensure that we check one node only once:
 112          */
 113         unsigned int                    version;
 114
 115         /*
 116          * Statistics counter:
 117          */
 118         unsigned long                   ops;
 119
 120         const char                      *name;
 121         int                             name_version;
 122
 123 #ifdef CONFIG_LOCK_STAT
 124         unsigned long                   contention_point[LOCKSTAT_POINTS];
 125         unsigned long                   contending_point[LOCKSTAT_POINTS];
 126 #endif
 127 };
 128
 129 #ifdef CONFIG_LOCK_STAT
 130 struct lock_time {
 131         s64                             min;
 132         s64                             max;
 133         s64                             total;
 134         unsigned long                   nr;
 135 };
 136
 137 enum bounce_type {
 138         bounce_acquired_write,
 139         bounce_acquired_read,
 140         bounce_contended_write,
 141         bounce_contended_read,
 142         nr_bounce_types,
 143
 144         bounce_acquired = bounce_acquired_write,
 145         bounce_contended = bounce_contended_write,
 146 };
 147
 148 struct lock_class_stats {
 149         unsigned long                   contention_point[4];
 150         unsigned long                   contending_point[4];
 151         struct lock_time                read_waittime;
 152         struct lock_time                write_waittime;
 153         struct lock_time                read_holdtime;
 154         struct lock_time                write_holdtime;
 155         unsigned long                   bounces[nr_bounce_types];
 156 };
 157
 158 struct lock_class_stats lock_stats(struct lock_class *class);
 159 void clear_lock_stats(struct lock_class *class);
 160 #endif
 161
 162 /*
 163  * Map the lock object (the lock instance) to the lock-class object.
 164  * This is embedded into specific lock instances:
 165  */
 166 struct lockdep_map {
 167         struct lock_class_key           *key;
 168         struct lock_class               *class_cache;
 169         const char                      *name;
 170 #ifdef CONFIG_LOCK_STAT
 171         int                             cpu;
 172         unsigned long                   ip;
 173 #endif
 174 };
 175
 176 /*
 177  * Every lock has a list of other locks that were taken after it.
 178  * We only grow the list, never remove from it:
 179  */
 180 struct lock_list {
 181         struct list_head                entry;
 182         struct lock_class               *class;
 183         struct stack_trace              trace;
 184         int                             distance;
 185 };
 186
 187 /*
 188  * We record lock dependency chains, so that we can cache them:
 189  */
 190 struct lock_chain {
 191         u8                              irq_context;
 192         u8                              depth;
 193         u16                             base;
 194         struct list_head                entry;
 195         u64                             chain_key;
 196 };
 197
 198 #define MAX_LOCKDEP_KEYS_BITS           13
 199 /*
 200  * Subtract one because we offset hlock->class_idx by 1 in order
 201  * to make 0 mean no class. This avoids overflowing the class_idx
 202  * bitfield and hitting the BUG in hlock_class().
 203  */
 204 #define MAX_LOCKDEP_KEYS                ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)
 205
 206 struct held_lock {
 207         /*
 208          * One-way hash of the dependency chain up to this point. We
 209          * hash the hashes step by step as the dependency chain grows.
 210          *
 211          * We use it for dependency-caching and we skip detection
 212          * passes and dependency-updates if there is a cache-hit, so
 213          * it is absolutely critical for 100% coverage of the validator
 214          * to have a unique key value for every unique dependency path
 215          * that can occur in the system, to make a unique hash value
 216          * as likely as possible - hence the 64-bit width.
 217          *
 218          * The task struct holds the current hash value (initialized
 219          * with zero), here we store the previous hash value:
 220          */
 221         u64                             prev_chain_key;
 222         unsigned long                   acquire_ip;
 223         struct lockdep_map              *instance;
 224         struct lockdep_map              *nest_lock;
 225 #ifdef CONFIG_LOCK_STAT
 226         u64                             waittime_stamp;
 227         u64                             holdtime_stamp;
 228 #endif
 229         unsigned int                    class_idx:MAX_LOCKDEP_KEYS_BITS;
 230         /*
 231          * The lock-stack is unified in that the lock chains of interrupt
 232          * contexts nest ontop of process context chains, but we 'separate'
 233          * the hashes by starting with 0 if we cross into an interrupt
 234          * context, and we also keep do not add cross-context lock
 235          * dependencies - the lock usage graph walking covers that area
 236          * anyway, and we'd just unnecessarily increase the number of
 237          * dependencies otherwise. [Note: hardirq and softirq contexts
 238          * are separated from each other too.]
 239          *
 240          * The following field is used to detect when we cross into an
 241          * interrupt context:
 242          */
 243         unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 244         unsigned int trylock:1;
 245         unsigned int read:2;        /* see lock_acquire() comment */
 246         unsigned int check:2;       /* see lock_acquire() comment */
 247         unsigned int hardirqs_off:1;
 248 };
 249
 250 /*
 251  * Initialization, self-test and debugging-output methods:
 252  */
 253 extern void lockdep_init(void);
 254 extern void lockdep_info(void);
 255 extern void lockdep_reset(void);
 256 extern void lockdep_reset_lock(struct lockdep_map *lock);
 257 extern void lockdep_free_key_range(void *start, unsigned long size);
 258 extern void lockdep_sys_exit(void);
 259
 260 extern void lockdep_off(void);
 261 extern void lockdep_on(void);
 262
 263 /*
 264  * These methods are used by specific locking variants (spinlocks,
 265  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 266  * to lockdep:
 267  */
 268
 269 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 270                              struct lock_class_key *key, int subclass);
 271
 272 /*
 273  * To initialize a lockdep_map statically use this macro.
 274  * Note that _name must not be NULL.
 275  */
 276 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 277         { .name = (_name), .key = (void *)(_key), }
 278
 279 /*
 280  * Reinitialize a lock key - for cases where there is special locking or
 281  * special initialization of locks so that the validator gets the scope
 282  * of dependencies wrong: they are either too broad (they need a class-split)
 283  * or they are too narrow (they suffer from a false class-split):
 284  */
 285 #define lockdep_set_class(lock, key) \
 286                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 287 #define lockdep_set_class_and_name(lock, key, name) \
 288                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 289 #define lockdep_set_class_and_subclass(lock, key, sub) \
 290                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 291 #define lockdep_set_subclass(lock, sub) \
 292                 lockdep_init_map(&(lock)->dep_map, #lock, \
 293                                  (lock)->dep_map.key, sub)
 294
 295 /*
 296  * Acquire a lock.
 297  *
 298  * Values for "read":
 299  *
 300  *   0: exclusive (write) acquire
 301  *   1: read-acquire (no recursion allowed)
 302  *   2: read-acquire with same-instance recursion allowed
 303  *
 304  * Values for check:
 305  *
 306  *   0: disabled
 307  *   1: simple checks (freeing, held-at-exit-time, etc.)
 308  *   2: full validation
 309  */
 310 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 311                          int trylock, int read, int check,
 312                          struct lockdep_map *nest_lock, unsigned long ip);
 313
 314 extern void lock_release(struct lockdep_map *lock, int nested,
 315                          unsigned long ip);
 316
 317 extern void lock_set_subclass(struct lockdep_map *lock, unsigned int subclass,
 318                               unsigned long ip);
 319
 320 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 321
 322 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 323
 324 #else /* !LOCKDEP */
 325
 326 static inline void lockdep_off(void)
 327 {
 328 }
 329
 330 static inline void lockdep_on(void)
 331 {
 332 }
 333
 334 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 335 # define lock_release(l, n, i)                  do { } while (0)
 336 # define lock_set_subclass(l, s, i)             do { } while (0)
 337 # define lockdep_init()                         do { } while (0)
 338 # define lockdep_info()                         do { } while (0)
 339 # define lockdep_init_map(lock, name, key, sub) \
 340                 do { (void)(name); (void)(key); } while (0)
 341 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 342 # define lockdep_set_class_and_name(lock, key, name) \
 343                 do { (void)(key); (void)(name); } while (0)
 344 #define lockdep_set_class_and_subclass(lock, key, sub) \
 345                 do { (void)(key); } while (0)
 346 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 347
 348 # define INIT_LOCKDEP
 349 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 350 # define lockdep_free_key_range(start, size)    do { } while (0)
 351 # define lockdep_sys_exit()                     do { } while (0)
 352 /*
 353  * The class key takes no space if lockdep is disabled:
 354  */
 355 struct lock_class_key { };
 356
 357 #define lockdep_depth(tsk)      (0)
 358
 359 #endif /* !LOCKDEP */
 360
 361 #ifdef CONFIG_LOCK_STAT
 362
 363 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 364 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 365
 366 #define LOCK_CONTENDED(_lock, try, lock)                        \
 367 do {                                                            \
 368         if (!try(_lock)) {                                      \
 369                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 370                 lock(_lock);                                    \
 371         }                                                       \
 372         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 373 } while (0)
 374
 375 #else /* CONFIG_LOCK_STAT */
 376
 377 #define lock_contended(lockdep_map, ip) do {} while (0)
 378 #define lock_acquired(lockdep_map, ip) do {} while (0)
 379
 380 #define LOCK_CONTENDED(_lock, try, lock) \
 381         lock(_lock)
 382
 383 #endif /* CONFIG_LOCK_STAT */
 384
 385 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
 386 extern void early_init_irq_lock_class(void);
 387 #else
 388 static inline void early_init_irq_lock_class(void)
 389 {
 390 }
 391 #endif
 392
 393 #ifdef CONFIG_TRACE_IRQFLAGS
 394 extern void early_boot_irqs_off(void);
 395 extern void early_boot_irqs_on(void);
 396 extern void print_irqtrace_events(struct task_struct *curr);
 397 #else
 398 static inline void early_boot_irqs_off(void)
 399 {
 400 }
 401 static inline void early_boot_irqs_on(void)
 402 {
 403 }
 404 static inline void print_irqtrace_events(struct task_struct *curr)
 405 {
 406 }
 407 #endif
 408
 409 /*
 410  * For trivial one-depth nesting of a lock-class, the following
 411  * global define can be used. (Subsystems with multiple levels
 412  * of nesting should define their own lock-nesting subclasses.)
 413  */
 414 #define SINGLE_DEPTH_NESTING                    1
 415
 416 /*
 417  * Map the dependency ops to NOP or to real lockdep ops, depending
 418  * on the per lock-class debug mode:
 419  */
 420
 421 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 422 # ifdef CONFIG_PROVE_LOCKING
 423 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 424 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 425 # else
 426 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 427 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 428 # endif
 429 # define spin_release(l, n, i)                  lock_release(l, n, i)
 430 #else
 431 # define spin_acquire(l, s, t, i)               do { } while (0)
 432 # define spin_release(l, n, i)                  do { } while (0)
 433 #endif
 434
 435 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 436 # ifdef CONFIG_PROVE_LOCKING
 437 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 438 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 439 # else
 440 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 441 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 442 # endif
 443 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 444 #else
 445 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 446 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 447 # define rwlock_release(l, n, i)                do { } while (0)
 448 #endif
 449
 450 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 451 # ifdef CONFIG_PROVE_LOCKING
 452 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 453 # else
 454 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 455 # endif
 456 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 457 #else
 458 # define mutex_acquire(l, s, t, i)              do { } while (0)
 459 # define mutex_release(l, n, i)                 do { } while (0)
 460 #endif
 461
 462 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 463 # ifdef CONFIG_PROVE_LOCKING
 464 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 465 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 466 # else
 467 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 468 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 469 # endif
 470 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 471 #else
 472 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 473 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 474 # define rwsem_release(l, n, i)                 do { } while (0)
 475 #endif
 476
 477 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 478 # ifdef CONFIG_PROVE_LOCKING
 479 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 480 # else
 481 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 482 # endif
 483 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 484 #else
 485 # define lock_map_acquire(l)                    do { } while (0)
 486 # define lock_map_release(l)                    do { } while (0)
 487 #endif
 488
 489 #ifdef CONFIG_PROVE_LOCKING
 490 # define might_lock(lock)                                               \
 491 do {                                                                    \
 492         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 493         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 494         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 495 } while (0)
 496 # define might_lock_read(lock)                                          \
 497 do {                                                                    \
 498         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 499         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 500         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 501 } while (0)
 502 #else
 503 # define might_lock(lock) do { } while (0)
 504 # define might_lock_read(lock) do { } while (0)
 505 #endif
 506
 507 #endif /* __LINUX_LOCKDEP_H */