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 };
 138
 139 /*
 140  * We record lock dependency chains, so that we can cache them:
 141  */
 142 struct lock_chain {
 143         struct list_head                entry;
 144         u64                             chain_key;
 145 };
 146
 147 struct held_lock {
 148         /*
 149          * One-way hash of the dependency chain up to this point. We
 150          * hash the hashes step by step as the dependency chain grows.
 151          *
 152          * We use it for dependency-caching and we skip detection
 153          * passes and dependency-updates if there is a cache-hit, so
 154          * it is absolutely critical for 100% coverage of the validator
 155          * to have a unique key value for every unique dependency path
 156          * that can occur in the system, to make a unique hash value
 157          * as likely as possible - hence the 64-bit width.
 158          *
 159          * The task struct holds the current hash value (initialized
 160          * with zero), here we store the previous hash value:
 161          */
 162         u64                             prev_chain_key;
 163         struct lock_class               *class;
 164         unsigned long                   acquire_ip;
 165         struct lockdep_map              *instance;
 166
 167         /*
 168          * The lock-stack is unified in that the lock chains of interrupt
 169          * contexts nest ontop of process context chains, but we 'separate'
 170          * the hashes by starting with 0 if we cross into an interrupt
 171          * context, and we also keep do not add cross-context lock
 172          * dependencies - the lock usage graph walking covers that area
 173          * anyway, and we'd just unnecessarily increase the number of
 174          * dependencies otherwise. [Note: hardirq and softirq contexts
 175          * are separated from each other too.]
 176          *
 177          * The following field is used to detect when we cross into an
 178          * interrupt context:
 179          */
 180         int                             irq_context;
 181         int                             trylock;
 182         int                             read;
 183         int                             check;
 184         int                             hardirqs_off;
 185 };
 186
 187 /*
 188  * Initialization, self-test and debugging-output methods:
 189  */
 190 extern void lockdep_init(void);
 191 extern void lockdep_info(void);
 192 extern void lockdep_reset(void);
 193 extern void lockdep_reset_lock(struct lockdep_map *lock);
 194 extern void lockdep_free_key_range(void *start, unsigned long size);
 195
 196 extern void lockdep_off(void);
 197 extern void lockdep_on(void);
 198
 199 /*
 200  * These methods are used by specific locking variants (spinlocks,
 201  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
 202  * to lockdep:
 203  */
 204
 205 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 206                              struct lock_class_key *key, int subclass);
 207
 208 /*
 209  * Reinitialize a lock key - for cases where there is special locking or
 210  * special initialization of locks so that the validator gets the scope
 211  * of dependencies wrong: they are either too broad (they need a class-split)
 212  * or they are too narrow (they suffer from a false class-split):
 213  */
 214 #define lockdep_set_class(lock, key) \
 215                 lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 216 #define lockdep_set_class_and_name(lock, key, name) \
 217                 lockdep_init_map(&(lock)->dep_map, name, key, 0)
 218 #define lockdep_set_class_and_subclass(lock, key, sub) \
 219                 lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 220 #define lockdep_set_subclass(lock, sub) \
 221                 lockdep_init_map(&(lock)->dep_map, #lock, \
 222                                  (lock)->dep_map.key, sub)
 223
 224 /*
 225  * Acquire a lock.
 226  *
 227  * Values for "read":
 228  *
 229  *   0: exclusive (write) acquire
 230  *   1: read-acquire (no recursion allowed)
 231  *   2: read-acquire with same-instance recursion allowed
 232  *
 233  * Values for check:
 234  *
 235  *   0: disabled
 236  *   1: simple checks (freeing, held-at-exit-time, etc.)
 237  *   2: full validation
 238  */
 239 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 240                          int trylock, int read, int check, unsigned long ip);
 241
 242 extern void lock_release(struct lockdep_map *lock, int nested,
 243                          unsigned long ip);
 244
 245 # define INIT_LOCKDEP                           .lockdep_recursion = 0,
 246
 247 #define lockdep_depth(tsk)      ((tsk)->lockdep_depth)
 248
 249 #else /* !LOCKDEP */
 250
 251 static inline void lockdep_off(void)
 252 {
 253 }
 254
 255 static inline void lockdep_on(void)
 256 {
 257 }
 258
 259 # define lock_acquire(l, s, t, r, c, i)         do { } while (0)
 260 # define lock_release(l, n, i)                  do { } while (0)
 261 # define lockdep_init()                         do { } while (0)
 262 # define lockdep_info()                         do { } while (0)
 263 # define lockdep_init_map(lock, name, key, sub) do { (void)(key); } while (0)
 264 # define lockdep_set_class(lock, key)           do { (void)(key); } while (0)
 265 # define lockdep_set_class_and_name(lock, key, name) \
 266                 do { (void)(key); } while (0)
 267 #define lockdep_set_class_and_subclass(lock, key, sub) \
 268                 do { (void)(key); } while (0)
 269 #define lockdep_set_subclass(lock, sub)         do { } while (0)
 270
 271 # define INIT_LOCKDEP
 272 # define lockdep_reset()                do { debug_locks = 1; } while (0)
 273 # define lockdep_free_key_range(start, size)    do { } while (0)
 274 /*
 275  * The class key takes no space if lockdep is disabled:
 276  */
 277 struct lock_class_key { };
 278
 279 #define lockdep_depth(tsk)      (0)
 280
 281 #endif /* !LOCKDEP */
 282
 283 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
 284 extern void early_init_irq_lock_class(void);
 285 #else
 286 static inline void early_init_irq_lock_class(void)
 287 {
 288 }
 289 #endif
 290
 291 #ifdef CONFIG_TRACE_IRQFLAGS
 292 extern void early_boot_irqs_off(void);
 293 extern void early_boot_irqs_on(void);
 294 extern void print_irqtrace_events(struct task_struct *curr);
 295 #else
 296 static inline void early_boot_irqs_off(void)
 297 {
 298 }
 299 static inline void early_boot_irqs_on(void)
 300 {
 301 }
 302 static inline void print_irqtrace_events(struct task_struct *curr)
 303 {
 304 }
 305 #endif
 306
 307 /*
 308  * For trivial one-depth nesting of a lock-class, the following
 309  * global define can be used. (Subsystems with multiple levels
 310  * of nesting should define their own lock-nesting subclasses.)
 311  */
 312 #define SINGLE_DEPTH_NESTING                    1
 313
 314 /*
 315  * Map the dependency ops to NOP or to real lockdep ops, depending
 316  * on the per lock-class debug mode:
 317  */
 318
 319 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 320 # ifdef CONFIG_PROVE_LOCKING
 321 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 2, i)
 322 # else
 323 #  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, i)
 324 # endif
 325 # define spin_release(l, n, i)                  lock_release(l, n, i)
 326 #else
 327 # define spin_acquire(l, s, t, i)               do { } while (0)
 328 # define spin_release(l, n, i)                  do { } while (0)
 329 #endif
 330
 331 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 332 # ifdef CONFIG_PROVE_LOCKING
 333 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 2, i)
 334 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, i)
 335 # else
 336 #  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, i)
 337 #  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, i)
 338 # endif
 339 # define rwlock_release(l, n, i)                lock_release(l, n, i)
 340 #else
 341 # define rwlock_acquire(l, s, t, i)             do { } while (0)
 342 # define rwlock_acquire_read(l, s, t, i)        do { } while (0)
 343 # define rwlock_release(l, n, i)                do { } while (0)
 344 #endif
 345
 346 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 347 # ifdef CONFIG_PROVE_LOCKING
 348 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 349 # else
 350 #  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 351 # endif
 352 # define mutex_release(l, n, i)                 lock_release(l, n, i)
 353 #else
 354 # define mutex_acquire(l, s, t, i)              do { } while (0)
 355 # define mutex_release(l, n, i)                 do { } while (0)
 356 #endif
 357
 358 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 359 # ifdef CONFIG_PROVE_LOCKING
 360 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 2, i)
 361 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, i)
 362 # else
 363 #  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
 364 #  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, i)
 365 # endif
 366 # define rwsem_release(l, n, i)                 lock_release(l, n, i)
 367 #else
 368 # define rwsem_acquire(l, s, t, i)              do { } while (0)
 369 # define rwsem_acquire_read(l, s, t, i)         do { } while (0)
 370 # define rwsem_release(l, n, i)                 do { } while (0)
 371 #endif
 372
 373 #endif /* __LINUX_LOCKDEP_H */