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
  13 #ifdef CONFIG_LOCKDEP
  14
  15 #include <linux/linkage.h>
  16 #include <linux/list.h>
  17 #include <linux/debug_locks.h>
  18 #include <linux/stacktrace.h>
  19
  20 /*
  21  * Lock-class usage-state bits:
  22  */
  23 enum lock_usage_bit
  24 {
  25         LOCK_USED = 0,
  26         LOCK_USED_IN_HARDIRQ,
  27         LOCK_USED_IN_SOFTIRQ,
  28         LOCK_ENABLED_SOFTIRQS,
  29         LOCK_ENABLED_HARDIRQS,
  30         LOCK_USED_IN_HARDIRQ_READ,
  31         LOCK_USED_IN_SOFTIRQ_READ,
  32         LOCK_ENABLED_SOFTIRQS_READ,
  33         LOCK_ENABLED_HARDIRQS_READ,
  34         LOCK_USAGE_STATES
  35 };
  36
  37 /*
  38  * Usage-state bitmasks:
  39  */
  40 #define LOCKF_USED                      (1 << LOCK_USED)
  41 #define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
  42 #define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
  43 #define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
  44 #define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)
  45
  46 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
  47 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
  48
  49 #define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
  50 #define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
  51 #define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
  52 #define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)
  53
  54 #define LOCKF_ENABLED_IRQS_READ \
  55                 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
  56 #define LOCKF_USED_IN_IRQ_READ \
  57                 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
  58
  59 #define MAX_LOCKDEP_SUBCLASSES          8UL
  60
  61 /*
  62  * Lock-classes are keyed via unique addresses, by embedding the
  63  * lockclass-key into the kernel (or module) .data section. (For
  64  * static locks we use the lock address itself as the key.)
  65  */
  66 struct lockdep_subclass_key {
  67         char __one_byte;
  68 } __attribute__ ((__packed__));
  69
  70 struct lock_class_key {
  71         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  72 };
  73
  74 /*
  75  * The lock-class itself:
  76  */
  77 struct lock_class {
  78         /*
  79          * class-hash:
  80          */
  81         struct list_head                hash_entry;
  82
  83         /*
  84          * global list of all lock-classes:
  85          */
  86         struct list_head                lock_entry;
  87
  88         struct lockdep_subclass_key     *key;
  89         unsigned int                    subclass;
  90
  91         /*
  92          * IRQ/softirq usage tracking bits:
  93          */
  94         unsigned long                   usage_mask;
  95         struct stack_trace              usage_traces[LOCK_USAGE_STATES];
  96
  97         /*
  98          * These fields represent a directed graph of lock dependencies,
  99          * to every node we attach a list of "forward" and a list of
 100          * "backward" graph nodes.
 101          */
 102         struct list_head                locks_after, locks_before;
 103
 104         /*
 105          * Generation counter, when doing certain classes of graph walking,
 106          * to ensure that we check one node only once:
 107          */
 108         unsigned int                    version;
 109
 110         /*
 111          * Statistics counter:
 112          */
 113         unsigned long                   ops;
 114
 115         const char                      *name;
 116         int                             name_version;
 117 };
 118
 119 /*
 120  * Map the lock object (the lock instance) to the lock-class object.
 121  * This is embedded into specific lock instances:
 122  */
 123 struct lockdep_map {
 124         struct lock_class_key           *key;
 125         struct lock_class               *class_cache;
 126         const char                      *name;
 127 };
 128
 129 /*
 130  * Every lock has a list of other locks that were taken after it.
 131  * We only grow the list, never remove from it:
 132  */
 133 struct lock_list {
 134         struct list_head                entry;
 135         struct lock_class               *class;
 136         struct stack_trace              trace;
 137         int                             distance;
 138 };
 139
 140 /*
 141  * We record lock dependency chains, so that we can cache them:
 142  */
 143 struct lock_chain {
 144         struct list_head                entry;
 145         u64                             chain_key;
 146 };
 147
 148 struct held_lock {
 149         /*
 150          * One-way hash of the dependency chain up to this point. We
 151          * hash the hashes step by step as the dependency chain grows.
 152          *
 153          * We use it for dependency-caching and we skip detection
 154          * passes and dependency-updates if there is a cache-hit, so
 155          * it is absolutely critical for 100% coverage of the validator
 156          * to have a unique key value for every unique dependency path
 157          * that can occur in the system, to make a unique hash value
 158          * as likely as possible - hence the 64-bit width.
 159          *
 160          * The task struct holds the current hash value (initialized
 161          * with zero), here we store the previous hash value:
 162          */
 163         u64                             prev_chain_key;
 164         struct lock_class               *class;
 165         unsigned long                   acquire_ip;
 166         struct lockdep_map              *instance;
 167
 168         /*
 169          * The lock-stack is unified in that the lock chains of interrupt
 170          * contexts nest ontop of process context chains, but we 'separate'
 171          * the hashes by starting with 0 if we cross into an interrupt
 172          * context, and we also keep do not add cross-context lock
 173          * dependencies - the lock usage graph walking covers that area
 174          * anyway, and we'd just unnecessarily increase the number of
 175          * dependencies otherwise. [Note: hardirq and softirq contexts
 176          * are separated from each other too.]
 177          *
 178          * The following field is used to detect when we cross into an
 179          * interrupt context:
 180          */
 181         int                             irq_context;
 182         int                             trylock;
 183         int                             read;
 184         int                             check;
 185         int                             hardirqs_off;
 186 };
 187
 188 /*
 189  * Initialization, self-test and debugging-output methods:
 190  */
 191 extern void lockdep_init(void);
 192 extern void lockdep_info(void);
 193 extern void lockdep_reset(void);
 194 extern void lockdep_reset_lock(struct lockdep_map *lock);
 195 extern void lockdep_free_key_range(void *start, unsigned long size);
 196
 197 extern void lockdep_off(void);
 198 extern void lockdep_on(void);
 199
 200 /*
 201  * These methods are used by specific locking variants (spinlocks,
 202  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 203  * to lockdep:
 204  */
 205
 206 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 207                              struct lock_class_key *key, int subclass);
 208
 209 /*
 210  * Reinitialize a lock key - for cases where there is special locking or
 211  * special initialization of locks so that the validator gets the scope
 212  * of dependencies wrong: they are either too broad (they need a class-split)
 213  * or they are too narrow (they suffer from a false class-split):
 214  */
 215 #define lockdep_set_class(lock, key) \
 216                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 217 #define lockdep_set_class_and_name(lock, key, name) \
 218                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 219 #define lockdep_set_class_and_subclass(lock, key, sub) \
 220                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 221 #define lockdep_set_subclass(lock, sub) \
 222                 lockdep_init_map(&(lock)->dep_map, #lock, \
 223                                  (lock)->dep_map.key, sub)
 224
 225 /*
 226  * Acquire a lock.
 227  *
 228  * Values for "read":
 229  *
 230  *   0: exclusive (write) acquire
 231  *   1: read-acquire (no recursion allowed)
 232  *   2: read-acquire with same-instance recursion allowed
 233  *
 234  * Values for check:
 235  *
 236  *   0: disabled
 237  *   1: simple checks (freeing, held-at-exit-time, etc.)
 238  *   2: full validation
 239  */
 240 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 241                          int trylock, int read, int check, unsigned long ip);
 242
 243 extern void lock_release(struct lockdep_map *lock, int nested,
 244                          unsigned long ip);
 245
 246 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 247
 248 #define lockdep_depth(tsk)      ((tsk)->lockdep_depth)
 249
 250 #else /* !LOCKDEP */
 251
 252 static inline void lockdep_off(void)
 253 {
 254 }
 255
 256 static inline void lockdep_on(void)
 257 {
 258 }
 259
 260 # define lock_acquire(l, s, t, r, c, i)         do { } while (0)
 261 # define lock_release(l, n, i)                  do { } while (0)
 262 # define lockdep_init()                         do { } while (0)
 263 # define lockdep_info()                         do { } while (0)
 264 # define lockdep_init_map(lock, name, key, sub) do { (void)(key); } while (0)
 265 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 266 # define lockdep_set_class_and_name(lock, key, name) \
 267                 do { (void)(key); } while (0)
 268 #define lockdep_set_class_and_subclass(lock, key, sub) \
 269                 do { (void)(key); } while (0)
 270 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 271
 272 # define INIT_LOCKDEP
 273 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 274 # define lockdep_free_key_range(start, size)    do { } while (0)
 275 /*
 276  * The class key takes no space if lockdep is disabled:
 277  */
 278 struct lock_class_key { };
 279
 280 #define lockdep_depth(tsk)      (0)
 281
 282 #endif /* !LOCKDEP */
 283
 284 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
 285 extern void early_init_irq_lock_class(void);
 286 #else
 287 static inline void early_init_irq_lock_class(void)
 288 {
 289 }
 290 #endif
 291
 292 #ifdef CONFIG_TRACE_IRQFLAGS
 293 extern void early_boot_irqs_off(void);
 294 extern void early_boot_irqs_on(void);
 295 extern void print_irqtrace_events(struct task_struct *curr);
 296 #else
 297 static inline void early_boot_irqs_off(void)
 298 {
 299 }
 300 static inline void early_boot_irqs_on(void)
 301 {
 302 }
 303 static inline void print_irqtrace_events(struct task_struct *curr)
 304 {
 305 }
 306 #endif
 307
 308 /*
 309  * For trivial one-depth nesting of a lock-class, the following
 310  * global define can be used. (Subsystems with multiple levels
 311  * of nesting should define their own lock-nesting subclasses.)
 312  */
 313 #define SINGLE_DEPTH_NESTING                    1
 314
 315 /*
 316  * Map the dependency ops to NOP or to real lockdep ops, depending
 317  * on the per lock-class debug mode:
 318  */
 319
 320 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 321 # ifdef CONFIG_PROVE_LOCKING
 322 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, i)
 323 # else
 324 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, i)
 325 # endif
 326 # define spin_release(l, n, i)                  lock_release(l, n, i)
 327 #else
 328 # define spin_acquire(l, s, t, i)               do { } while (0)
 329 # define spin_release(l, n, i)                  do { } while (0)
 330 #endif
 331
 332 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 333 # ifdef CONFIG_PROVE_LOCKING
 334 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, i)
 335 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, i)
 336 # else
 337 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, i)
 338 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, i)
 339 # endif
 340 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 341 #else
 342 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 343 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 344 # define rwlock_release(l, n, i)                do { } while (0)
 345 #endif
 346
 347 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 348 # ifdef CONFIG_PROVE_LOCKING
 349 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 350 # else
 351 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 352 # endif
 353 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 354 #else
 355 # define mutex_acquire(l, s, t, i)              do { } while (0)
 356 # define mutex_release(l, n, i)                 do { } while (0)
 357 #endif
 358
 359 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 360 # ifdef CONFIG_PROVE_LOCKING
 361 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 362 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, i)
 363 # else
 364 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 365 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, i)
 366 # endif
 367 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 368 #else
 369 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 370 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 371 # define rwsem_release(l, n, i)                 do { } while (0)
 372 #endif
 373
 374 #endif /* __LINUX_LOCKDEP_H */