include/linux/lockdep.h

   1 /*
   2  * Runtime locking correctness validator
   3  *
   4  *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   5  *
   6  * see Documentation/lockdep-design.txt for more details.
   7  */
   8 #ifndef __LINUX_LOCKDEP_H
   9 #define __LINUX_LOCKDEP_H
  10
  11 struct task_struct;
  12 struct lockdep_map;
  13
  14 #ifdef CONFIG_LOCKDEP
  15
  16 #include <linux/linkage.h>
  17 #include <linux/list.h>
  18 #include <linux/debug_locks.h>
  19 #include <linux/stacktrace.h>
  20
  21 /*
  22  * Lock-class usage-state bits:
  23  */
  24 enum lock_usage_bit
  25 {
  26         LOCK_USED = 0,
  27         LOCK_USED_IN_HARDIRQ,
  28         LOCK_USED_IN_SOFTIRQ,
  29         LOCK_ENABLED_SOFTIRQS,
  30         LOCK_ENABLED_HARDIRQS,
  31         LOCK_USED_IN_HARDIRQ_READ,
  32         LOCK_USED_IN_SOFTIRQ_READ,
  33         LOCK_ENABLED_SOFTIRQS_READ,
  34         LOCK_ENABLED_HARDIRQS_READ,
  35         LOCK_USAGE_STATES
  36 };
  37
  38 /*
  39  * Usage-state bitmasks:
  40  */
  41 #define LOCKF_USED                      (1 << LOCK_USED)
  42 #define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
  43 #define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
  44 #define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
  45 #define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)
  46
  47 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
  48 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
  49
  50 #define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
  51 #define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
  52 #define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
  53 #define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)
  54
  55 #define LOCKF_ENABLED_IRQS_READ \
  56                 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
  57 #define LOCKF_USED_IN_IRQ_READ \
  58                 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
  59
  60 #define MAX_LOCKDEP_SUBCLASSES          8UL
  61
  62 /*
  63  * Lock-classes are keyed via unique addresses, by embedding the
  64  * lockclass-key into the kernel (or module) .data section. (For
  65  * static locks we use the lock address itself as the key.)
  66  */
  67 struct lockdep_subclass_key {
  68         char __one_byte;
  69 } __attribute__ ((__packed__));
  70
  71 struct lock_class_key {
  72         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  73 };
  74
  75 /*
  76  * The lock-class itself:
  77  */
  78 struct lock_class {
  79         /*
  80          * class-hash:
  81          */
  82         struct list_head                hash_entry;
  83
  84         /*
  85          * global list of all lock-classes:
  86          */
  87         struct list_head                lock_entry;
  88
  89         struct lockdep_subclass_key     *key;
  90         unsigned int                    subclass;
  91
  92         /*
  93          * IRQ/softirq usage tracking bits:
  94          */
  95         unsigned long                   usage_mask;
  96         struct stack_trace              usage_traces[LOCK_USAGE_STATES];
  97
  98         /*
  99          * These fields represent a directed graph of lock dependencies,
 100          * to every node we attach a list of "forward" and a list of
 101          * "backward" graph nodes.
 102          */
 103         struct list_head                locks_after, locks_before;
 104
 105         /*
 106          * Generation counter, when doing certain classes of graph walking,
 107          * to ensure that we check one node only once:
 108          */
 109         unsigned int                    version;
 110
 111         /*
 112          * Statistics counter:
 113          */
 114         unsigned long                   ops;
 115
 116         const char                      *name;
 117         int                             name_version;
 118
 119 #ifdef CONFIG_LOCK_STAT
 120         unsigned long                   contention_point[4];
 121 #endif
 122 };
 123
 124 #ifdef CONFIG_LOCK_STAT
 125 struct lock_time {
 126         s64                             min;
 127         s64                             max;
 128         s64                             total;
 129         unsigned long                   nr;
 130 };
 131
 132 struct lock_class_stats {
 133         unsigned long                   contention_point[4];
 134         struct lock_time                read_waittime;
 135         struct lock_time                write_waittime;
 136         struct lock_time                read_holdtime;
 137         struct lock_time                write_holdtime;
 138 };
 139
 140 struct lock_class_stats lock_stats(struct lock_class *class);
 141 void clear_lock_stats(struct lock_class *class);
 142 #endif
 143
 144 /*
 145  * Map the lock object (the lock instance) to the lock-class object.
 146  * This is embedded into specific lock instances:
 147  */
 148 struct lockdep_map {
 149         struct lock_class_key           *key;
 150         struct lock_class               *class_cache;
 151         const char                      *name;
 152 };
 153
 154 /*
 155  * Every lock has a list of other locks that were taken after it.
 156  * We only grow the list, never remove from it:
 157  */
 158 struct lock_list {
 159         struct list_head                entry;
 160         struct lock_class               *class;
 161         struct stack_trace              trace;
 162         int                             distance;
 163 };
 164
 165 /*
 166  * We record lock dependency chains, so that we can cache them:
 167  */
 168 struct lock_chain {
 169         struct list_head                entry;
 170         u64                             chain_key;
 171 };
 172
 173 struct 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         struct lock_class               *class;
 190         unsigned long                   acquire_ip;
 191         struct lockdep_map              *instance;
 192
 193 #ifdef CONFIG_LOCK_STAT
 194         u64                             waittime_stamp;
 195         u64                             holdtime_stamp;
 196 #endif
 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         int                             irq_context;
 211         int                             trylock;
 212         int                             read;
 213         int                             check;
 214         int                             hardirqs_off;
 215 };
 216
 217 /*
 218  * Initialization, self-test and debugging-output methods:
 219  */
 220 extern void lockdep_init(void);
 221 extern void lockdep_info(void);
 222 extern void lockdep_reset(void);
 223 extern void lockdep_reset_lock(struct lockdep_map *lock);
 224 extern void lockdep_free_key_range(void *start, unsigned long size);
 225
 226 extern void lockdep_off(void);
 227 extern void lockdep_on(void);
 228
 229 /*
 230  * These methods are used by specific locking variants (spinlocks,
 231  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 232  * to lockdep:
 233  */
 234
 235 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 236                              struct lock_class_key *key, int subclass);
 237
 238 /*
 239  * Reinitialize a lock key - for cases where there is special locking or
 240  * special initialization of locks so that the validator gets the scope
 241  * of dependencies wrong: they are either too broad (they need a class-split)
 242  * or they are too narrow (they suffer from a false class-split):
 243  */
 244 #define lockdep_set_class(lock, key) \
 245                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 246 #define lockdep_set_class_and_name(lock, key, name) \
 247                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 248 #define lockdep_set_class_and_subclass(lock, key, sub) \
 249                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 250 #define lockdep_set_subclass(lock, sub) \
 251                 lockdep_init_map(&(lock)->dep_map, #lock, \
 252                                  (lock)->dep_map.key, sub)
 253
 254 /*
 255  * Acquire a lock.
 256  *
 257  * Values for "read":
 258  *
 259  *   0: exclusive (write) acquire
 260  *   1: read-acquire (no recursion allowed)
 261  *   2: read-acquire with same-instance recursion allowed
 262  *
 263  * Values for check:
 264  *
 265  *   0: disabled
 266  *   1: simple checks (freeing, held-at-exit-time, etc.)
 267  *   2: full validation
 268  */
 269 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 270                          int trylock, int read, int check, unsigned long ip);
 271
 272 extern void lock_release(struct lockdep_map *lock, int nested,
 273                          unsigned long ip);
 274
 275 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 276
 277 #define lockdep_depth(tsk)      (debug_locks ? (tsk)->lockdep_depth : 0)
 278
 279 #else /* !LOCKDEP */
 280
 281 static inline void lockdep_off(void)
 282 {
 283 }
 284
 285 static inline void lockdep_on(void)
 286 {
 287 }
 288
 289 # define lock_acquire(l, s, t, r, c, i)         do { } while (0)
 290 # define lock_release(l, n, i)                  do { } while (0)
 291 # define lockdep_init()                         do { } while (0)
 292 # define lockdep_info()                         do { } while (0)
 293 # define lockdep_init_map(lock, name, key, sub) do { (void)(key); } while (0)
 294 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 295 # define lockdep_set_class_and_name(lock, key, name) \
 296                 do { (void)(key); } while (0)
 297 #define lockdep_set_class_and_subclass(lock, key, sub) \
 298                 do { (void)(key); } while (0)
 299 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 300
 301 # define INIT_LOCKDEP
 302 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 303 # define lockdep_free_key_range(start, size)    do { } while (0)
 304 /*
 305  * The class key takes no space if lockdep is disabled:
 306  */
 307 struct lock_class_key { };
 308
 309 #define lockdep_depth(tsk)      (0)
 310
 311 #endif /* !LOCKDEP */
 312
 313 #ifdef CONFIG_LOCK_STAT
 314
 315 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 316 extern void lock_acquired(struct lockdep_map *lock);
 317
 318 #define LOCK_CONTENDED(_lock, try, lock)                        \
 319 do {                                                            \
 320         if (!try(_lock)) {                                      \
 321                 lock_contended(&(_lock)->dep_map, _RET_IP_);    \
 322                 lock(_lock);                                    \
 323                 lock_acquired(&(_lock)->dep_map);               \
 324         }                                                       \
 325 } while (0)
 326
 327 #else /* CONFIG_LOCK_STAT */
 328
 329 #define lock_contended(lockdep_map, ip) do {} while (0)
 330 #define lock_acquired(lockdep_map) do {} while (0)
 331
 332 #define LOCK_CONTENDED(_lock, try, lock) \
 333         lock(_lock)
 334
 335 #endif /* CONFIG_LOCK_STAT */
 336
 337 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
 338 extern void early_init_irq_lock_class(void);
 339 #else
 340 static inline void early_init_irq_lock_class(void)
 341 {
 342 }
 343 #endif
 344
 345 #ifdef CONFIG_TRACE_IRQFLAGS
 346 extern void early_boot_irqs_off(void);
 347 extern void early_boot_irqs_on(void);
 348 extern void print_irqtrace_events(struct task_struct *curr);
 349 #else
 350 static inline void early_boot_irqs_off(void)
 351 {
 352 }
 353 static inline void early_boot_irqs_on(void)
 354 {
 355 }
 356 static inline void print_irqtrace_events(struct task_struct *curr)
 357 {
 358 }
 359 #endif
 360
 361 /*
 362  * For trivial one-depth nesting of a lock-class, the following
 363  * global define can be used. (Subsystems with multiple levels
 364  * of nesting should define their own lock-nesting subclasses.)
 365  */
 366 #define SINGLE_DEPTH_NESTING                    1
 367
 368 /*
 369  * Map the dependency ops to NOP or to real lockdep ops, depending
 370  * on the per lock-class debug mode:
 371  */
 372
 373 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 374 # ifdef CONFIG_PROVE_LOCKING
 375 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, i)
 376 # else
 377 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, i)
 378 # endif
 379 # define spin_release(l, n, i)                  lock_release(l, n, i)
 380 #else
 381 # define spin_acquire(l, s, t, i)               do { } while (0)
 382 # define spin_release(l, n, i)                  do { } while (0)
 383 #endif
 384
 385 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 386 # ifdef CONFIG_PROVE_LOCKING
 387 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, i)
 388 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, i)
 389 # else
 390 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, i)
 391 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, i)
 392 # endif
 393 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 394 #else
 395 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 396 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 397 # define rwlock_release(l, n, i)                do { } while (0)
 398 #endif
 399
 400 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 401 # ifdef CONFIG_PROVE_LOCKING
 402 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 403 # else
 404 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 405 # endif
 406 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 407 #else
 408 # define mutex_acquire(l, s, t, i)              do { } while (0)
 409 # define mutex_release(l, n, i)                 do { } while (0)
 410 #endif
 411
 412 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 413 # ifdef CONFIG_PROVE_LOCKING
 414 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 415 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, i)
 416 # else
 417 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 418 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, i)
 419 # endif
 420 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 421 #else
 422 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 423 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 424 # define rwsem_release(l, n, i)                 do { } while (0)
 425 #endif
 426
 427 #endif /* __LINUX_LOCKDEP_H */