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_class(struct lockdep_map *lock, const char *name,
 318                            struct lock_class_key *key, unsigned int subclass,
 319                            unsigned long ip);
 320
 321 static inline void lock_set_subclass(struct lockdep_map *lock,
 322                 unsigned int subclass, unsigned long ip)
 323 {
 324         lock_set_class(lock, lock->name, lock->key, subclass, ip);
 325 }
 326
 327 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 328
 329 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 330
 331 #else /* !LOCKDEP */
 332
 333 static inline void lockdep_off(void)
 334 {
 335 }
 336
 337 static inline void lockdep_on(void)
 338 {
 339 }
 340
 341 # define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 342 # define lock_release(l, n, i)                  do { } while (0)
 343 # define lock_set_class(l, n, k, s, i)          do { } while (0)
 344 # define lock_set_subclass(l, s, i)             do { } while (0)
 345 # define lockdep_init()                         do { } while (0)
 346 # define lockdep_info()                         do { } while (0)
 347 # define lockdep_init_map(lock, name, key, sub) \
 348                 do { (void)(name); (void)(key); } while (0)
 349 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 350 # define lockdep_set_class_and_name(lock, key, name) \
 351                 do { (void)(key); (void)(name); } while (0)
 352 #define lockdep_set_class_and_subclass(lock, key, sub) \
 353                 do { (void)(key); } while (0)
 354 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 355
 356 # define INIT_LOCKDEP
 357 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 358 # define lockdep_free_key_range(start, size)    do { } while (0)
 359 # define lockdep_sys_exit()                     do { } while (0)
 360 /*
 361  * The class key takes no space if lockdep is disabled:
 362  */
 363 struct lock_class_key { };
 364
 365 #define lockdep_depth(tsk)      (0)
 366
 367 #endif /* !LOCKDEP */
 368
 369 #ifdef CONFIG_LOCK_STAT
 370
 371 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 372 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 373
 374 #define LOCK_CONTENDED(_lock, try, lock)                        \
 375 do {                                                            \
 376         if (!try(_lock)) {                                      \
 377                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 378                 lock(_lock);                                    \
 379         }                                                       \
 380         lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 381 } while (0)
 382
 383 #else /* CONFIG_LOCK_STAT */
 384
 385 #define lock_contended(lockdep_map, ip) do {} while (0)
 386 #define lock_acquired(lockdep_map, ip) do {} while (0)
 387
 388 #define LOCK_CONTENDED(_lock, try, lock) \
 389         lock(_lock)
 390
 391 #endif /* CONFIG_LOCK_STAT */
 392
 393 #ifdef CONFIG_GENERIC_HARDIRQS
 394 extern void early_init_irq_lock_class(void);
 395 #else
 396 static inline void early_init_irq_lock_class(void)
 397 {
 398 }
 399 #endif
 400
 401 #ifdef CONFIG_TRACE_IRQFLAGS
 402 extern void early_boot_irqs_off(void);
 403 extern void early_boot_irqs_on(void);
 404 extern void print_irqtrace_events(struct task_struct *curr);
 405 #else
 406 static inline void early_boot_irqs_off(void)
 407 {
 408 }
 409 static inline void early_boot_irqs_on(void)
 410 {
 411 }
 412 static inline void print_irqtrace_events(struct task_struct *curr)
 413 {
 414 }
 415 #endif
 416
 417 /*
 418  * For trivial one-depth nesting of a lock-class, the following
 419  * global define can be used. (Subsystems with multiple levels
 420  * of nesting should define their own lock-nesting subclasses.)
 421  */
 422 #define SINGLE_DEPTH_NESTING                    1
 423
 424 /*
 425  * Map the dependency ops to NOP or to real lockdep ops, depending
 426  * on the per lock-class debug mode:
 427  */
 428
 429 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 430 # ifdef CONFIG_PROVE_LOCKING
 431 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 432 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 433 # else
 434 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 435 #  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 436 # endif
 437 # define spin_release(l, n, i)                  lock_release(l, n, i)
 438 #else
 439 # define spin_acquire(l, s, t, i)               do { } while (0)
 440 # define spin_release(l, n, i)                  do { } while (0)
 441 #endif
 442
 443 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 444 # ifdef CONFIG_PROVE_LOCKING
 445 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 446 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 447 # else
 448 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 449 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 450 # endif
 451 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 452 #else
 453 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 454 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 455 # define rwlock_release(l, n, i)                do { } while (0)
 456 #endif
 457
 458 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 459 # ifdef CONFIG_PROVE_LOCKING
 460 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 461 # else
 462 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 463 # endif
 464 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 465 #else
 466 # define mutex_acquire(l, s, t, i)              do { } while (0)
 467 # define mutex_release(l, n, i)                 do { } while (0)
 468 #endif
 469
 470 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 471 # ifdef CONFIG_PROVE_LOCKING
 472 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 473 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 474 # else
 475 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 476 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 477 # endif
 478 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 479 #else
 480 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 481 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 482 # define rwsem_release(l, n, i)                 do { } while (0)
 483 #endif
 484
 485 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 486 # ifdef CONFIG_PROVE_LOCKING
 487 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 488 # else
 489 #  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 490 # endif
 491 # define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 492 #else
 493 # define lock_map_acquire(l)                    do { } while (0)
 494 # define lock_map_release(l)                    do { } while (0)
 495 #endif
 496
 497 #ifdef CONFIG_PROVE_LOCKING
 498 # define might_lock(lock)                                               \
 499 do {                                                                    \
 500         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 501         lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 502         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 503 } while (0)
 504 # define might_lock_read(lock)                                          \
 505 do {                                                                    \
 506         typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 507         lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 508         lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 509 } while (0)
 510 #else
 511 # define might_lock(lock) do { } while (0)
 512 # define might_lock_read(lock) do { } while (0)
 513 #endif
 514
 515 #endif /* __LINUX_LOCKDEP_H */