LXR linux/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
  12struct task_struct;
  13struct 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 */
  35struct lockdep_subclass_key {
  36        char __one_byte;
  37} __attribute__ ((__packed__));
  38
  39struct 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 */
  48struct 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
  97struct lock_time {
  98        s64                             min;
  99        s64                             max;
 100        s64                             total;
 101        unsigned long                   nr;
 102};
 103
 104enum 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
 115struct 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
 125struct lock_class_stats lock_stats(struct lock_class *class);
 126void 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 */
 133struct 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 */
 147struct 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 */
 157struct 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
 173struct 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 */
 220extern void lockdep_init(void);
 221extern void lockdep_info(void);
 222extern void lockdep_reset(void);
 223extern void lockdep_reset_lock(struct lockdep_map *lock);
 224extern void lockdep_free_key_range(void *start, unsigned long size);
 225extern void lockdep_sys_exit(void);
 226
 227extern void lockdep_off(void);
 228extern 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
 236extern 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 * Compare locking classes
 263 */
 264#define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
 265
 266static inline int lockdep_match_key(struct lockdep_map *lock,
 267                                    struct lock_class_key *key)
 268{
 269        return lock->key == key;
 270}
 271
 272/*
 273 * Acquire a lock.
 274 *
 275 * Values for "read":
 276 *
 277 *   0: exclusive (write) acquire
 278 *   1: read-acquire (no recursion allowed)
 279 *   2: read-acquire with same-instance recursion allowed
 280 *
 281 * Values for check:
 282 *
 283 *   0: disabled
 284 *   1: simple checks (freeing, held-at-exit-time, etc.)
 285 *   2: full validation
 286 */
 287extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 288                         int trylock, int read, int check,
 289                         struct lockdep_map *nest_lock, unsigned long ip);
 290
 291extern void lock_release(struct lockdep_map *lock, int nested,
 292                         unsigned long ip);
 293
 294extern void lock_set_class(struct lockdep_map *lock, const char *name,
 295                           struct lock_class_key *key, unsigned int subclass,
 296                           unsigned long ip);
 297
 298static inline void lock_set_subclass(struct lockdep_map *lock,
 299                unsigned int subclass, unsigned long ip)
 300{
 301        lock_set_class(lock, lock->name, lock->key, subclass, ip);
 302}
 303
 304extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 305extern void lockdep_clear_current_reclaim_state(void);
 306extern void lockdep_trace_alloc(gfp_t mask);
 307
 308# define INIT_LOCKDEP                           .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,
 309
 310#define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 311
 312#else /* !LOCKDEP */
 313
 314static inline void lockdep_off(void)
 315{
 316}
 317
 318static inline void lockdep_on(void)
 319{
 320}
 321
 322# define lock_acquire(l, s, t, r, c, n, i)      do { } while (0)
 323# define lock_release(l, n, i)                  do { } while (0)
 324# define lock_set_class(l, n, k, s, i)          do { } while (0)
 325# define lock_set_subclass(l, s, i)             do { } while (0)
 326# define lockdep_set_current_reclaim_state(g)   do { } while (0)
 327# define lockdep_clear_current_reclaim_state()  do { } while (0)
 328# define lockdep_trace_alloc(g)                 do { } while (0)
 329# define lockdep_init()                         do { } while (0)
 330# define lockdep_info()                         do { } while (0)
 331# define lockdep_init_map(lock, name, key, sub) \
 332                do { (void)(name); (void)(key); } while (0)
 333# define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 334# define lockdep_set_class_and_name(lock, key, name) \
 335                do { (void)(key); (void)(name); } while (0)
 336#define lockdep_set_class_and_subclass(lock, key, sub) \
 337                do { (void)(key); } while (0)
 338#define lockdep_set_subclass(lock, sub)         do { } while (0)
 339/*
 340 * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
 341 * case since the result is not well defined and the caller should rather
 342 * #ifdef the call himself.
 343 */
 344
 345# define INIT_LOCKDEP
 346# define lockdep_reset()                do { debug_locks = 1; } while (0)
 347# define lockdep_free_key_range(start, size)    do { } while (0)
 348# define lockdep_sys_exit()                     do { } while (0)
 349/*
 350 * The class key takes no space if lockdep is disabled:
 351 */
 352struct lock_class_key { };
 353
 354#define lockdep_depth(tsk)      (0)
 355
 356#endif /* !LOCKDEP */
 357
 358#ifdef CONFIG_LOCK_STAT
 359
 360extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 361extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 362
 363#define LOCK_CONTENDED(_lock, try, lock)                        \
 364do {                                                            \
 365        if (!try(_lock)) {                                      \
 366                lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 367                lock(_lock);                                    \
 368        }                                                       \
 369        lock_acquired(&(_lock)->dep_map, _RET_IP_);                     \
 370} while (0)
 371
 372#else /* CONFIG_LOCK_STAT */
 373
 374#define lock_contended(lockdep_map, ip) do {} while (0)
 375#define lock_acquired(lockdep_map, ip) do {} while (0)
 376
 377#define LOCK_CONTENDED(_lock, try, lock) \
 378        lock(_lock)
 379
 380#endif /* CONFIG_LOCK_STAT */
 381
 382#ifdef CONFIG_LOCKDEP
 383
 384/*
 385 * On lockdep we dont want the hand-coded irq-enable of
 386 * _raw_*_lock_flags() code, because lockdep assumes
 387 * that interrupts are not re-enabled during lock-acquire:
 388 */
 389#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 390        LOCK_CONTENDED((_lock), (try), (lock))
 391
 392#else /* CONFIG_LOCKDEP */
 393
 394#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 395        lockfl((_lock), (flags))
 396
 397#endif /* CONFIG_LOCKDEP */
 398
 399#ifdef CONFIG_GENERIC_HARDIRQS
 400extern void early_init_irq_lock_class(void);
 401#else
 402static inline void early_init_irq_lock_class(void)
 403{
 404}
 405#endif
 406
 407#ifdef CONFIG_TRACE_IRQFLAGS
 408extern void early_boot_irqs_off(void);
 409extern void early_boot_irqs_on(void);
 410extern void print_irqtrace_events(struct task_struct *curr);
 411#else
 412static inline void early_boot_irqs_off(void)
 413{
 414}
 415static inline void early_boot_irqs_on(void)
 416{
 417}
 418static inline void print_irqtrace_events(struct task_struct *curr)
 419{
 420}
 421#endif
 422
 423/*
 424 * For trivial one-depth nesting of a lock-class, the following
 425 * global define can be used. (Subsystems with multiple levels
 426 * of nesting should define their own lock-nesting subclasses.)
 427 */
 428#define SINGLE_DEPTH_NESTING                    1
 429
 430/*
 431 * Map the dependency ops to NOP or to real lockdep ops, depending
 432 * on the per lock-class debug mode:
 433 */
 434
 435#ifdef CONFIG_DEBUG_LOCK_ALLOC
 436# ifdef CONFIG_PROVE_LOCKING
 437#  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, NULL, i)
 438#  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 2, n, i)
 439# else
 440#  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, NULL, i)
 441#  define spin_acquire_nest(l, s, t, n, i)      lock_acquire(l, s, t, 0, 1, NULL, i)
 442# endif
 443# define spin_release(l, n, i)                  lock_release(l, n, i)
 444#else
 445# define spin_acquire(l, s, t, i)               do { } while (0)
 446# define spin_release(l, n, i)                  do { } while (0)
 447#endif
 448
 449#ifdef CONFIG_DEBUG_LOCK_ALLOC
 450# ifdef CONFIG_PROVE_LOCKING
 451#  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, NULL, i)
 452#  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, NULL, i)
 453# else
 454#  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, NULL, i)
 455#  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, NULL, i)
 456# endif
 457# define rwlock_release(l, n, i)                lock_release(l, n, i)
 458#else
 459# define rwlock_acquire(l, s, t, i)             do { } while (0)
 460# define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 461# define rwlock_release(l, n, i)                do { } while (0)
 462#endif
 463
 464#ifdef CONFIG_DEBUG_LOCK_ALLOC
 465# ifdef CONFIG_PROVE_LOCKING
 466#  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 467# else
 468#  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 469# endif
 470# define mutex_release(l, n, i)                 lock_release(l, n, i)
 471#else
 472# define mutex_acquire(l, s, t, i)              do { } while (0)
 473# define mutex_release(l, n, i)                 do { } while (0)
 474#endif
 475
 476#ifdef CONFIG_DEBUG_LOCK_ALLOC
 477# ifdef CONFIG_PROVE_LOCKING
 478#  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, NULL, i)
 479#  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, NULL, i)
 480# else
 481#  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, NULL, i)
 482#  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, NULL, i)
 483# endif
 484# define rwsem_release(l, n, i)                 lock_release(l, n, i)
 485#else
 486# define rwsem_acquire(l, s, t, i)              do { } while (0)
 487# define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 488# define rwsem_release(l, n, i)                 do { } while (0)
 489#endif
 490
 491#ifdef CONFIG_DEBUG_LOCK_ALLOC
 492# ifdef CONFIG_PROVE_LOCKING
 493#  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 494# else
 495#  define lock_map_acquire(l)           lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 496# endif
 497# define lock_map_release(l)                    lock_release(l, 1, _THIS_IP_)
 498#else
 499# define lock_map_acquire(l)                    do { } while (0)
 500# define lock_map_release(l)                    do { } while (0)
 501#endif
 502
 503#ifdef CONFIG_PROVE_LOCKING
 504# define might_lock(lock)                                               \
 505do {                                                                    \
 506        typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 507        lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);    \
 508        lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 509} while (0)
 510# define might_lock_read(lock)                                          \
 511do {                                                                    \
 512        typecheck(struct lockdep_map *, &(lock)->dep_map);              \
 513        lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);    \
 514        lock_release(&(lock)->dep_map, 0, _THIS_IP_);                   \
 515} while (0)
 516#else
 517# define might_lock(lock) do { } while (0)
 518# define might_lock_read(lock) do { } while (0)
 519#endif
 520
 521#endif /* __LINUX_LOCKDEP_H */
 522