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 #ifdef CONFIG_LOCKDEP
  12
  13 #include <linux/linkage.h>
  14 #include <linux/list.h>
  15 #include <linux/debug_locks.h>
  16 #include <linux/stacktrace.h>
  17
  18 /*
  19  * Lock-class usage-state bits:
  20  */
  21 enum lock_usage_bit
  22 {
  23         LOCK_USED = 0,
  24         LOCK_USED_IN_HARDIRQ,
  25         LOCK_USED_IN_SOFTIRQ,
  26         LOCK_ENABLED_SOFTIRQS,
  27         LOCK_ENABLED_HARDIRQS,
  28         LOCK_USED_IN_HARDIRQ_READ,
  29         LOCK_USED_IN_SOFTIRQ_READ,
  30         LOCK_ENABLED_SOFTIRQS_READ,
  31         LOCK_ENABLED_HARDIRQS_READ,
  32         LOCK_USAGE_STATES
  33 };
  34
  35 /*
  36  * Usage-state bitmasks:
  37  */
  38 #define LOCKF_USED                      (1 << LOCK_USED)
  39 #define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
  40 #define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
  41 #define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
  42 #define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)
  43
  44 #define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
  45 #define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)
  46
  47 #define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
  48 #define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
  49 #define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
  50 #define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)
  51
  52 #define LOCKF_ENABLED_IRQS_READ \
  53                 (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
  54 #define LOCKF_USED_IN_IRQ_READ \
  55                 (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
  56
  57 #define MAX_LOCKDEP_SUBCLASSES          8UL
  58
  59 /*
  60  * Lock-classes are keyed via unique addresses, by embedding the
  61  * lockclass-key into the kernel (or module) .data section. (For
  62  * static locks we use the lock address itself as the key.)
  63  */
  64 struct lockdep_subclass_key {
  65         char __one_byte;
  66 } __attribute__ ((__packed__));
  67
  68 struct lock_class_key {
  69         struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
  70 };
  71
  72 /*
  73  * The lock-class itself:
  74  */
  75 struct lock_class {
  76         /*
  77          * class-hash:
  78          */
  79         struct list_head                hash_entry;
  80
  81         /*
  82          * global list of all lock-classes:
  83          */
  84         struct list_head                lock_entry;
  85
  86         struct lockdep_subclass_key     *key;
  87         unsigned int                    subclass;
  88
  89         /*
  90          * IRQ/softirq usage tracking bits:
  91          */
  92         unsigned long                   usage_mask;
  93         struct stack_trace              usage_traces[LOCK_USAGE_STATES];
  94
  95         /*
  96          * These fields represent a directed graph of lock dependencies,
  97          * to every node we attach a list of "forward" and a list of
  98          * "backward" graph nodes.
  99          */
 100         struct list_head                locks_after, locks_before;
 101
 102         /*
 103          * Generation counter, when doing certain classes of graph walking,
 104          * to ensure that we check one node only once:
 105          */
 106         unsigned int                    version;
 107
 108         /*
 109          * Statistics counter:
 110          */
 111         unsigned long                   ops;
 112
 113         const char                      *name;
 114         int                             name_version;
 115 };
 116
 117 /*
 118  * Map the lock object (the lock instance) to the lock-class object.
 119  * This is embedded into specific lock instances:
 120  */
 121 struct lockdep_map {
 122         struct lock_class_key           *key;
 123         struct lock_class               *class_cache;
 124         const char                      *name;
 125 };
 126
 127 /*
 128  * Every lock has a list of other locks that were taken after it.
 129  * We only grow the list, never remove from it:
 130  */
 131 struct lock_list {
 132         struct list_head                entry;
 133         struct lock_class               *class;
 134         struct stack_trace              trace;
 135 };
 136
 137 /*
 138  * We record lock dependency chains, so that we can cache them:
 139  */
 140 struct lock_chain {
 141         struct list_head                entry;
 142         u64                             chain_key;
 143 };
 144
 145 struct held_lock {
 146         /*
 147          * One-way hash of the dependency chain up to this point. We
 148          * hash the hashes step by step as the dependency chain grows.
 149          *
 150          * We use it for dependency-caching and we skip detection
 151          * passes and dependency-updates if there is a cache-hit, so
 152          * it is absolutely critical for 100% coverage of the validator
 153          * to have a unique key value for every unique dependency path
 154          * that can occur in the system, to make a unique hash value
 155          * as likely as possible - hence the 64-bit width.
 156          *
 157          * The task struct holds the current hash value (initialized
 158          * with zero), here we store the previous hash value:
 159          */
 160         u64                             prev_chain_key;
 161         struct lock_class               *class;
 162         unsigned long                   acquire_ip;
 163         struct lockdep_map              *instance;
 164
 165         /*
 166          * The lock-stack is unified in that the lock chains of interrupt
 167          * contexts nest ontop of process context chains, but we 'separate'
 168          * the hashes by starting with 0 if we cross into an interrupt
 169          * context, and we also keep do not add cross-context lock
 170          * dependencies - the lock usage graph walking covers that area
 171          * anyway, and we'd just unnecessarily increase the number of
 172          * dependencies otherwise. [Note: hardirq and softirq contexts
 173          * are separated from each other too.]
 174          *
 175          * The following field is used to detect when we cross into an
 176          * interrupt context:
 177          */
 178         int                             irq_context;
 179         int                             trylock;
 180         int                             read;
 181         int                             check;
 182         int                             hardirqs_off;
 183 };
 184
 185 /*
 186  * Initialization, self-test and debugging-output methods:
 187  */
 188 extern void lockdep_init(void);
 189 extern void lockdep_info(void);
 190 extern void lockdep_reset(void);
 191 extern void lockdep_reset_lock(struct lockdep_map *lock);
 192 extern void lockdep_free_key_range(void *start, unsigned long size);
 193
 194 extern void lockdep_off(void);
 195 extern void lockdep_on(void);
 196 extern int lockdep_internal(void);
 197
 198 /*
 199  * These methods are used by specific locking variants (spinlocks,
 200  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 201  * to lockdep:
 202  */
 203
 204 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 205                              struct lock_class_key *key);
 206
 207 /*
 208  * Reinitialize a lock key - for cases where there is special locking or
 209  * special initialization of locks so that the validator gets the scope
 210  * of dependencies wrong: they are either too broad (they need a class-split)
 211  * or they are too narrow (they suffer from a false class-split):
 212  */
 213 #define lockdep_set_class(lock, key) \
 214                 lockdep_init_map(&(lock)->dep_map, #key, key)
 215 #define lockdep_set_class_and_name(lock, key, name) \
 216                 lockdep_init_map(&(lock)->dep_map, name, key)
 217
 218 /*
 219  * Acquire a lock.
 220  *
 221  * Values for "read":
 222  *
 223  *   0: exclusive (write) acquire
 224  *   1: read-acquire (no recursion allowed)
 225  *   2: read-acquire with same-instance recursion allowed
 226  *
 227  * Values for check:
 228  *
 229  *   0: disabled
 230  *   1: simple checks (freeing, held-at-exit-time, etc.)
 231  *   2: full validation
 232  */
 233 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 234                          int trylock, int read, int check, unsigned long ip);
 235
 236 extern void lock_release(struct lockdep_map *lock, int nested,
 237                          unsigned long ip);
 238
 239 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 240
 241 #else /* !LOCKDEP */
 242
 243 static inline void lockdep_off(void)
 244 {
 245 }
 246
 247 static inline void lockdep_on(void)
 248 {
 249 }
 250
 251 static inline int lockdep_internal(void)
 252 {
 253         return 0;
 254 }
 255
 256 # define lock_acquire(l, s, t, r, c, i)         do { } while (0)
 257 # define lock_release(l, n, i)                  do { } while (0)
 258 # define lockdep_init()                         do { } while (0)
 259 # define lockdep_info()                         do { } while (0)
 260 # define lockdep_init_map(lock, name, key)      do { (void)(key); } while (0)
 261 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 262 # define lockdep_set_class_and_name(lock, key, name) \
 263                 do { (void)(key); } while (0)
 264 # define INIT_LOCKDEP
 265 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 266 # define lockdep_free_key_range(start, size)    do { } while (0)
 267 /*
 268  * The class key takes no space if lockdep is disabled:
 269  */
 270 struct lock_class_key { };
 271 #endif /* !LOCKDEP */
 272
 273 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
 274 extern void early_init_irq_lock_class(void);
 275 #else
 276 # define early_init_irq_lock_class()            do { } while (0)
 277 #endif
 278
 279 #ifdef CONFIG_TRACE_IRQFLAGS
 280 extern void early_boot_irqs_off(void);
 281 extern void early_boot_irqs_on(void);
 282 #else
 283 # define early_boot_irqs_off()                  do { } while (0)
 284 # define early_boot_irqs_on()                   do { } while (0)
 285 #endif
 286
 287 /*
 288  * For trivial one-depth nesting of a lock-class, the following
 289  * global define can be used. (Subsystems with multiple levels
 290  * of nesting should define their own lock-nesting subclasses.)
 291  */
 292 #define SINGLE_DEPTH_NESTING                    1
 293
 294 /*
 295  * Map the dependency ops to NOP or to real lockdep ops, depending
 296  * on the per lock-class debug mode:
 297  */
 298
 299 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 300 # ifdef CONFIG_PROVE_LOCKING
 301 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, i)
 302 # else
 303 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, i)
 304 # endif
 305 # define spin_release(l, n, i)                  lock_release(l, n, i)
 306 #else
 307 # define spin_acquire(l, s, t, i)               do { } while (0)
 308 # define spin_release(l, n, i)                  do { } while (0)
 309 #endif
 310
 311 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 312 # ifdef CONFIG_PROVE_LOCKING
 313 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, i)
 314 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, i)
 315 # else
 316 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, i)
 317 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, i)
 318 # endif
 319 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 320 #else
 321 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 322 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 323 # define rwlock_release(l, n, i)                do { } while (0)
 324 #endif
 325
 326 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 327 # ifdef CONFIG_PROVE_LOCKING
 328 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 329 # else
 330 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 331 # endif
 332 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 333 #else
 334 # define mutex_acquire(l, s, t, i)              do { } while (0)
 335 # define mutex_release(l, n, i)                 do { } while (0)
 336 #endif
 337
 338 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 339 # ifdef CONFIG_PROVE_LOCKING
 340 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 341 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, i)
 342 # else
 343 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 344 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, i)
 345 # endif
 346 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 347 #else
 348 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 349 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 350 # define rwsem_release(l, n, i)                 do { } while (0)
 351 #endif
 352
 353 #endif /* __LINUX_LOCKDEP_H */