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