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