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