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 * Lock-class usage-state bits:
  24 */
  25enum 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 */
  68struct lockdep_subclass_key {
  69        char __one_byte;
  70} __attribute__ ((__packed__));
  71
  72struct 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 */
  81struct 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
 130struct lock_time {
 131        s64                             min;
 132        s64                             max;
 133        s64                             total;
 134        unsigned long                   nr;
 135};
 136
 137enum 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
 148struct 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
 158struct lock_class_stats lock_stats(struct lock_class *class);
 159void 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 */
 166struct 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 */
 180struct 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 */
 190struct 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
 206struct 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 */
 253extern void lockdep_init(void);
 254extern void lockdep_info(void);
 255extern void lockdep_reset(void);
 256extern void lockdep_reset_lock(struct lockdep_map *lock);
 257extern void lockdep_free_key_range(void *start, unsigned long size);
 258extern void lockdep_sys_exit(void);
 259
 260extern void lockdep_off(void);
 261extern 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
 269extern 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 */
 310extern 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
 314extern void lock_release(struct lockdep_map *lock, int nested,
 315                         unsigned long ip);
 316
 317extern 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
 321static 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
 333static inline void lockdep_off(void)
 334{
 335}
 336
 337static 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 */
 363struct lock_class_key { };
 364
 365#define lockdep_depth(tsk)      (0)
 366
 367#endif /* !LOCKDEP */
 368
 369#ifdef CONFIG_LOCK_STAT
 370
 371extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 372extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);
 373
 374#define LOCK_CONTENDED(_lock, try, lock)                        \
 375do {                                                            \
 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
 394extern void early_init_irq_lock_class(void);
 395#else
 396static inline void early_init_irq_lock_class(void)
 397{
 398}
 399#endif
 400
 401#ifdef CONFIG_TRACE_IRQFLAGS
 402extern void early_boot_irqs_off(void);
 403extern void early_boot_irqs_on(void);
 404extern void print_irqtrace_events(struct task_struct *curr);
 405#else
 406static inline void early_boot_irqs_off(void)
 407{
 408}
 409static inline void early_boot_irqs_on(void)
 410{
 411}
 412static 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)                                               \
 499do {                                                                    \
 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)                                          \
 505do {                                                                    \
 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 */
 516