include/linux/lockdep.h - kernel/msm-5.4 - Gitiles

 /*
  * Runtime locking correctness validator
  *
  *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  *
  * see Documentation/lockdep-design.txt for more details.
  */
 #ifndef __LINUX_LOCKDEP_H
 #define __LINUX_LOCKDEP_H

 struct task_struct;
 struct lockdep_map;

 /* for sysctl */
 extern int prove_locking;
 extern int lock_stat;

 #ifdef CONFIG_LOCKDEP

 #include <linux/linkage.h>
 #include <linux/list.h>
 #include <linux/debug_locks.h>
 #include <linux/stacktrace.h>

 /*
  * We'd rather not expose kernel/lockdep_states.h this wide, but we do need
  * the total number of states... :-(
  */
 #define XXX_LOCK_USAGE_STATES		(1+3*4)

 #define MAX_LOCKDEP_SUBCLASSES		8UL

 /*
  * NR_LOCKDEP_CACHING_CLASSES ... Number of classes
  * cached in the instance of lockdep_map
  *
  * Currently main class (subclass == 0) and signle depth subclass
  * are cached in lockdep_map. This optimization is mainly targeting
  * on rq->lock. double_rq_lock() acquires this highly competitive with
  * single depth.
  */
 #define NR_LOCKDEP_CACHING_CLASSES	2

 /*
  * Lock-classes are keyed via unique addresses, by embedding the
  * lockclass-key into the kernel (or module) .data section. (For
  * static locks we use the lock address itself as the key.)
  */
 struct lockdep_subclass_key {
 	char __one_byte;
 } __attribute__ ((__packed__));

 struct lock_class_key {
 	struct lockdep_subclass_key	subkeys[MAX_LOCKDEP_SUBCLASSES];
 };

 extern struct lock_class_key __lockdep_no_validate__;

 #define LOCKSTAT_POINTS		4

 /*
  * The lock-class itself:
  */
 struct lock_class {
 	/*
 	 * class-hash:
 	 */
 	struct list_head		hash_entry;

 	/*
 	 * global list of all lock-classes:
 	 */
 	struct list_head		lock_entry;

 	struct lockdep_subclass_key	*key;
 	unsigned int			subclass;
 	unsigned int			dep_gen_id;

 	/*
 	 * IRQ/softirq usage tracking bits:
 	 */
 	unsigned long			usage_mask;
 	struct stack_trace		usage_traces[XXX_LOCK_USAGE_STATES];

 	/*
 	 * These fields represent a directed graph of lock dependencies,
 	 * to every node we attach a list of "forward" and a list of
 	 * "backward" graph nodes.
 	 */
 	struct list_head		locks_after, locks_before;

 	/*
 	 * Generation counter, when doing certain classes of graph walking,
 	 * to ensure that we check one node only once:
 	 */
 	unsigned int			version;

 	/*
 	 * Statistics counter:
 	 */
 	unsigned long			ops;

 	const char			*name;
 	int				name_version;

 #ifdef CONFIG_LOCK_STAT
 	unsigned long			contention_point[LOCKSTAT_POINTS];
 	unsigned long			contending_point[LOCKSTAT_POINTS];
 #endif
 };

 #ifdef CONFIG_LOCK_STAT
 struct lock_time {
 	s64				min;
 	s64				max;
 	s64				total;
 	unsigned long			nr;
 };

 enum bounce_type {
 	bounce_acquired_write,
 	bounce_acquired_read,
 	bounce_contended_write,
 	bounce_contended_read,
 	nr_bounce_types,

 	bounce_acquired = bounce_acquired_write,
 	bounce_contended = bounce_contended_write,
 };

 struct lock_class_stats {
 	unsigned long			contention_point[4];
 	unsigned long			contending_point[4];
 	struct lock_time		read_waittime;
 	struct lock_time		write_waittime;
 	struct lock_time		read_holdtime;
 	struct lock_time		write_holdtime;
 	unsigned long			bounces[nr_bounce_types];
 };

 struct lock_class_stats lock_stats(struct lock_class *class);
 void clear_lock_stats(struct lock_class *class);
 #endif

 /*
  * Map the lock object (the lock instance) to the lock-class object.
  * This is embedded into specific lock instances:
  */
 struct lockdep_map {
 	struct lock_class_key		*key;
 	struct lock_class		*class_cache[NR_LOCKDEP_CACHING_CLASSES];
 	const char			*name;
 #ifdef CONFIG_LOCK_STAT
 	int				cpu;
 	unsigned long			ip;
 #endif
 };

 /*
  * Every lock has a list of other locks that were taken after it.
  * We only grow the list, never remove from it:
  */
 struct lock_list {
 	struct list_head		entry;
 	struct lock_class		*class;
 	struct stack_trace		trace;
 	int				distance;

 	/*
 	 * The parent field is used to implement breadth-first search, and the
 	 * bit 0 is reused to indicate if the lock has been accessed in BFS.
 	 */
 	struct lock_list		*parent;
 };

 /*
  * We record lock dependency chains, so that we can cache them:
  */
 struct lock_chain {
 	u8				irq_context;
 	u8				depth;
 	u16				base;
 	struct list_head		entry;
 	u64				chain_key;
 };

 #define MAX_LOCKDEP_KEYS_BITS		13
 /*
  * Subtract one because we offset hlock->class_idx by 1 in order
  * to make 0 mean no class. This avoids overflowing the class_idx
  * bitfield and hitting the BUG in hlock_class().
  */
 #define MAX_LOCKDEP_KEYS		((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)

 struct held_lock {
 	/*
 	 * One-way hash of the dependency chain up to this point. We
 	 * hash the hashes step by step as the dependency chain grows.
 	 *
 	 * We use it for dependency-caching and we skip detection
 	 * passes and dependency-updates if there is a cache-hit, so
 	 * it is absolutely critical for 100% coverage of the validator
 	 * to have a unique key value for every unique dependency path
 	 * that can occur in the system, to make a unique hash value
 	 * as likely as possible - hence the 64-bit width.
 	 *
 	 * The task struct holds the current hash value (initialized
 	 * with zero), here we store the previous hash value:
 	 */
 	u64				prev_chain_key;
 	unsigned long			acquire_ip;
 	struct lockdep_map		*instance;
 	struct lockdep_map		*nest_lock;
 #ifdef CONFIG_LOCK_STAT
 	u64 				waittime_stamp;
 	u64				holdtime_stamp;
 #endif
 	unsigned int			class_idx:MAX_LOCKDEP_KEYS_BITS;
 	/*
 	 * The lock-stack is unified in that the lock chains of interrupt
 	 * contexts nest ontop of process context chains, but we 'separate'
 	 * the hashes by starting with 0 if we cross into an interrupt
 	 * context, and we also keep do not add cross-context lock
 	 * dependencies - the lock usage graph walking covers that area
 	 * anyway, and we'd just unnecessarily increase the number of
 	 * dependencies otherwise. [Note: hardirq and softirq contexts
 	 * are separated from each other too.]
 	 *
 	 * The following field is used to detect when we cross into an
 	 * interrupt context:
 	 */
 	unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
 	unsigned int trylock:1;						/* 16 bits */

 	unsigned int read:2;        /* see lock_acquire() comment */
 	unsigned int check:2;       /* see lock_acquire() comment */
 	unsigned int hardirqs_off:1;
 	unsigned int references:11;					/* 32 bits */
 };

 /*
  * Initialization, self-test and debugging-output methods:
  */
 extern void lockdep_init(void);
 extern void lockdep_info(void);
 extern void lockdep_reset(void);
 extern void lockdep_reset_lock(struct lockdep_map *lock);
 extern void lockdep_free_key_range(void *start, unsigned long size);
 extern void lockdep_sys_exit(void);

 extern void lockdep_off(void);
 extern void lockdep_on(void);

 /*
  * These methods are used by specific locking variants (spinlocks,
  * rwlocks, mutexes and rwsems) to pass init/acquire/release events
  * to lockdep:
  */

 extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 			     struct lock_class_key *key, int subclass);

 /*
  * To initialize a lockdep_map statically use this macro.
  * Note that _name must not be NULL.
  */
 #define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
 	{ .name = (_name), .key = (void *)(_key), }

 /*
  * Reinitialize a lock key - for cases where there is special locking or
  * special initialization of locks so that the validator gets the scope
  * of dependencies wrong: they are either too broad (they need a class-split)
  * or they are too narrow (they suffer from a false class-split):
  */
 #define lockdep_set_class(lock, key) \
 		lockdep_init_map(&(lock)->dep_map, #key, key, 0)
 #define lockdep_set_class_and_name(lock, key, name) \
 		lockdep_init_map(&(lock)->dep_map, name, key, 0)
 #define lockdep_set_class_and_subclass(lock, key, sub) \
 		lockdep_init_map(&(lock)->dep_map, #key, key, sub)
 #define lockdep_set_subclass(lock, sub)	\
 		lockdep_init_map(&(lock)->dep_map, #lock, \
 				 (lock)->dep_map.key, sub)

 #define lockdep_set_novalidate_class(lock) \
 	lockdep_set_class(lock, &__lockdep_no_validate__)
 /*
  * Compare locking classes
  */
 #define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)

 static inline int lockdep_match_key(struct lockdep_map *lock,
 				    struct lock_class_key *key)
 {
 	return lock->key == key;
 }

 /*
  * Acquire a lock.
  *
  * Values for "read":
  *
  *   0: exclusive (write) acquire
  *   1: read-acquire (no recursion allowed)
  *   2: read-acquire with same-instance recursion allowed
  *
  * Values for check:
  *
  *   0: disabled
  *   1: simple checks (freeing, held-at-exit-time, etc.)
  *   2: full validation
  */
 extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 			 int trylock, int read, int check,
 			 struct lockdep_map *nest_lock, unsigned long ip);

 extern void lock_release(struct lockdep_map *lock, int nested,
 			 unsigned long ip);

 #define lockdep_is_held(lock)	lock_is_held(&(lock)->dep_map)

 extern int lock_is_held(struct lockdep_map *lock);

 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 			   struct lock_class_key *key, unsigned int subclass,
 			   unsigned long ip);

 static inline void lock_set_subclass(struct lockdep_map *lock,
 		unsigned int subclass, unsigned long ip)
 {
 	lock_set_class(lock, lock->name, lock->key, subclass, ip);
 }

 extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
 extern void lockdep_clear_current_reclaim_state(void);
 extern void lockdep_trace_alloc(gfp_t mask);

 # define INIT_LOCKDEP				.lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,

 #define lockdep_depth(tsk)	(debug_locks ? (tsk)->lockdep_depth : 0)

 #define lockdep_assert_held(l)	WARN_ON(debug_locks && !lockdep_is_held(l))

 #else /* !LOCKDEP */

 static inline void lockdep_off(void)
 {
 }

 static inline void lockdep_on(void)
 {
 }

 # define lock_acquire(l, s, t, r, c, n, i)	do { } while (0)
 # define lock_release(l, n, i)			do { } while (0)
 # define lock_set_class(l, n, k, s, i)		do { } while (0)
 # define lock_set_subclass(l, s, i)		do { } while (0)
 # define lockdep_set_current_reclaim_state(g)	do { } while (0)
 # define lockdep_clear_current_reclaim_state()	do { } while (0)
 # define lockdep_trace_alloc(g)			do { } while (0)
 # define lockdep_init()				do { } while (0)
 # define lockdep_info()				do { } while (0)
 # define lockdep_init_map(lock, name, key, sub) \
 		do { (void)(name); (void)(key); } while (0)
 # define lockdep_set_class(lock, key)		do { (void)(key); } while (0)
 # define lockdep_set_class_and_name(lock, key, name) \
 		do { (void)(key); (void)(name); } while (0)
 #define lockdep_set_class_and_subclass(lock, key, sub) \
 		do { (void)(key); } while (0)
 #define lockdep_set_subclass(lock, sub)		do { } while (0)

 #define lockdep_set_novalidate_class(lock) do { } while (0)

 /*
  * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
  * case since the result is not well defined and the caller should rather
  * #ifdef the call himself.
  */

 # define INIT_LOCKDEP
 # define lockdep_reset()		do { debug_locks = 1; } while (0)
 # define lockdep_free_key_range(start, size)	do { } while (0)
 # define lockdep_sys_exit() 			do { } while (0)
 /*
  * The class key takes no space if lockdep is disabled:
  */
 struct lock_class_key { };

 #define lockdep_depth(tsk)	(0)

 #define lockdep_assert_held(l)			do { } while (0)

 #endif /* !LOCKDEP */

 #ifdef CONFIG_LOCK_STAT

 extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
 extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);

 #define LOCK_CONTENDED(_lock, try, lock)			\
 do {								\
 	if (!try(_lock)) {					\
 		lock_contended(&(_lock)->dep_map, _RET_IP_);	\
 		lock(_lock);					\
 	}							\
 	lock_acquired(&(_lock)->dep_map, _RET_IP_);			\
 } while (0)

 #else /* CONFIG_LOCK_STAT */

 #define lock_contended(lockdep_map, ip) do {} while (0)
 #define lock_acquired(lockdep_map, ip) do {} while (0)

 #define LOCK_CONTENDED(_lock, try, lock) \
 	lock(_lock)

 #endif /* CONFIG_LOCK_STAT */

 #ifdef CONFIG_LOCKDEP

 /*
  * On lockdep we dont want the hand-coded irq-enable of
  * _raw_*_lock_flags() code, because lockdep assumes
  * that interrupts are not re-enabled during lock-acquire:
  */
 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 	LOCK_CONTENDED((_lock), (try), (lock))

 #else /* CONFIG_LOCKDEP */

 #define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
 	lockfl((_lock), (flags))

 #endif /* CONFIG_LOCKDEP */

 #ifdef CONFIG_TRACE_IRQFLAGS
 extern void print_irqtrace_events(struct task_struct *curr);
 #else
 static inline void print_irqtrace_events(struct task_struct *curr)
 {
 }
 #endif

 /*
  * For trivial one-depth nesting of a lock-class, the following
  * global define can be used. (Subsystems with multiple levels
  * of nesting should define their own lock-nesting subclasses.)
  */
 #define SINGLE_DEPTH_NESTING			1

 /*
  * Map the dependency ops to NOP or to real lockdep ops, depending
  * on the per lock-class debug mode:
  */

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define spin_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)
 #  define spin_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 2, n, i)
 # else
 #  define spin_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)
 #  define spin_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 1, NULL, i)
 # endif
 # define spin_release(l, n, i)			lock_release(l, n, i)
 #else
 # define spin_acquire(l, s, t, i)		do { } while (0)
 # define spin_release(l, n, i)			do { } while (0)
 #endif

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define rwlock_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)
 #  define rwlock_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 2, 2, NULL, i)
 # else
 #  define rwlock_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)
 #  define rwlock_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 2, 1, NULL, i)
 # endif
 # define rwlock_release(l, n, i)		lock_release(l, n, i)
 #else
 # define rwlock_acquire(l, s, t, i)		do { } while (0)
 # define rwlock_acquire_read(l, s, t, i)	do { } while (0)
 # define rwlock_release(l, n, i)		do { } while (0)
 #endif

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define mutex_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)
 # else
 #  define mutex_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)
 # endif
 # define mutex_release(l, n, i)			lock_release(l, n, i)
 #else
 # define mutex_acquire(l, s, t, i)		do { } while (0)
 # define mutex_release(l, n, i)			do { } while (0)
 #endif

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define rwsem_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)
 #  define rwsem_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 1, 2, NULL, i)
 # else
 #  define rwsem_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)
 #  define rwsem_acquire_read(l, s, t, i)	lock_acquire(l, s, t, 1, 1, NULL, i)
 # endif
 # define rwsem_release(l, n, i)			lock_release(l, n, i)
 #else
 # define rwsem_acquire(l, s, t, i)		do { } while (0)
 # define rwsem_acquire_read(l, s, t, i)		do { } while (0)
 # define rwsem_release(l, n, i)			do { } while (0)
 #endif

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define lock_map_acquire(l)		lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
 # else
 #  define lock_map_acquire(l)		lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
 # endif
 # define lock_map_release(l)			lock_release(l, 1, _THIS_IP_)
 #else
 # define lock_map_acquire(l)			do { } while (0)
 # define lock_map_release(l)			do { } while (0)
 #endif

 #ifdef CONFIG_PROVE_LOCKING
 # define might_lock(lock) 						\
 do {									\
 	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
 	lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_);	\
 	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
 } while (0)
 # define might_lock_read(lock) 						\
 do {									\
 	typecheck(struct lockdep_map *, &(lock)->dep_map);		\
 	lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_);	\
 	lock_release(&(lock)->dep_map, 0, _THIS_IP_);			\
 } while (0)
 #else
 # define might_lock(lock) do { } while (0)
 # define might_lock_read(lock) do { } while (0)
 #endif

 #ifdef CONFIG_PROVE_RCU
 extern void lockdep_rcu_dereference(const char *file, const int line);
 #endif

 #endif /* __LINUX_LOCKDEP_H */
	/*
	* Runtime locking correctness validator
	*
	* Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
	*
	* see Documentation/lockdep-design.txt for more details.
	*/
	#ifndef __LINUX_LOCKDEP_H
	#define __LINUX_LOCKDEP_H

	struct task_struct;
	struct lockdep_map;

	/* for sysctl */
	extern int prove_locking;
	extern int lock_stat;

	#ifdef CONFIG_LOCKDEP

	#include <linux/linkage.h>
	#include <linux/list.h>
	#include <linux/debug_locks.h>
	#include <linux/stacktrace.h>

	/*
	* We'd rather not expose kernel/lockdep_states.h this wide, but we do need
	* the total number of states... :-(
	*/
	#define XXX_LOCK_USAGE_STATES (1+3*4)

	#define MAX_LOCKDEP_SUBCLASSES 8UL

	/*
	* NR_LOCKDEP_CACHING_CLASSES ... Number of classes
	* cached in the instance of lockdep_map
	*
	* Currently main class (subclass == 0) and signle depth subclass
	* are cached in lockdep_map. This optimization is mainly targeting
	* on rq->lock. double_rq_lock() acquires this highly competitive with
	* single depth.
	*/
	#define NR_LOCKDEP_CACHING_CLASSES 2

	/*
	* Lock-classes are keyed via unique addresses, by embedding the
	* lockclass-key into the kernel (or module) .data section. (For
	* static locks we use the lock address itself as the key.)
	*/
	struct lockdep_subclass_key {
	char __one_byte;
	} __attribute__ ((__packed__));

	struct lock_class_key {
	struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
	};

	extern struct lock_class_key __lockdep_no_validate__;

	#define LOCKSTAT_POINTS 4

	/*
	* The lock-class itself:
	*/
	struct lock_class {
	/*
	* class-hash:
	*/
	struct list_head hash_entry;

	/*
	* global list of all lock-classes:
	*/
	struct list_head lock_entry;

	struct lockdep_subclass_key *key;
	unsigned int subclass;
	unsigned int dep_gen_id;

	/*
	* IRQ/softirq usage tracking bits:
	*/
	unsigned long usage_mask;
	struct stack_trace usage_traces[XXX_LOCK_USAGE_STATES];

	/*
	* These fields represent a directed graph of lock dependencies,
	* to every node we attach a list of "forward" and a list of
	* "backward" graph nodes.
	*/
	struct list_head locks_after, locks_before;

	/*
	* Generation counter, when doing certain classes of graph walking,
	* to ensure that we check one node only once:
	*/
	unsigned int version;

	/*
	* Statistics counter:
	*/
	unsigned long ops;

	const char *name;
	int name_version;

	#ifdef CONFIG_LOCK_STAT
	unsigned long contention_point[LOCKSTAT_POINTS];
	unsigned long contending_point[LOCKSTAT_POINTS];
	#endif
	};

	#ifdef CONFIG_LOCK_STAT
	struct lock_time {
	s64 min;
	s64 max;
	s64 total;
	unsigned long nr;
	};

	enum bounce_type {
	bounce_acquired_write,
	bounce_acquired_read,
	bounce_contended_write,
	bounce_contended_read,
	nr_bounce_types,

	bounce_acquired = bounce_acquired_write,
	bounce_contended = bounce_contended_write,
	};

	struct lock_class_stats {
	unsigned long contention_point[4];
	unsigned long contending_point[4];
	struct lock_time read_waittime;
	struct lock_time write_waittime;
	struct lock_time read_holdtime;
	struct lock_time write_holdtime;
	unsigned long bounces[nr_bounce_types];
	};

	struct lock_class_stats lock_stats(struct lock_class *class);
	void clear_lock_stats(struct lock_class *class);
	#endif

	/*
	* Map the lock object (the lock instance) to the lock-class object.
	* This is embedded into specific lock instances:
	*/
	struct lockdep_map {
	struct lock_class_key *key;
	struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES];
	const char *name;
	#ifdef CONFIG_LOCK_STAT
	int cpu;
	unsigned long ip;
	#endif
	};

	/*
	* Every lock has a list of other locks that were taken after it.
	* We only grow the list, never remove from it:
	*/
	struct lock_list {
	struct list_head entry;
	struct lock_class *class;
	struct stack_trace trace;
	int distance;

	/*
	* The parent field is used to implement breadth-first search, and the
	* bit 0 is reused to indicate if the lock has been accessed in BFS.
	*/
	struct lock_list *parent;
	};

	/*
	* We record lock dependency chains, so that we can cache them:
	*/
	struct lock_chain {
	u8 irq_context;
	u8 depth;
	u16 base;
	struct list_head entry;
	u64 chain_key;
	};

	#define MAX_LOCKDEP_KEYS_BITS 13
	/*
	* Subtract one because we offset hlock->class_idx by 1 in order
	* to make 0 mean no class. This avoids overflowing the class_idx
	* bitfield and hitting the BUG in hlock_class().
	*/
	#define MAX_LOCKDEP_KEYS ((1UL << MAX_LOCKDEP_KEYS_BITS) - 1)

	struct held_lock {
	/*
	* One-way hash of the dependency chain up to this point. We
	* hash the hashes step by step as the dependency chain grows.
	*
	* We use it for dependency-caching and we skip detection
	* passes and dependency-updates if there is a cache-hit, so
	* it is absolutely critical for 100% coverage of the validator
	* to have a unique key value for every unique dependency path
	* that can occur in the system, to make a unique hash value
	* as likely as possible - hence the 64-bit width.
	*
	* The task struct holds the current hash value (initialized
	* with zero), here we store the previous hash value:
	*/
	u64 prev_chain_key;
	unsigned long acquire_ip;
	struct lockdep_map *instance;
	struct lockdep_map *nest_lock;
	#ifdef CONFIG_LOCK_STAT
	u64 waittime_stamp;
	u64 holdtime_stamp;
	#endif
	unsigned int class_idx:MAX_LOCKDEP_KEYS_BITS;
	/*
	* The lock-stack is unified in that the lock chains of interrupt
	* contexts nest ontop of process context chains, but we 'separate'
	* the hashes by starting with 0 if we cross into an interrupt
	* context, and we also keep do not add cross-context lock
	* dependencies - the lock usage graph walking covers that area
	* anyway, and we'd just unnecessarily increase the number of
	* dependencies otherwise. [Note: hardirq and softirq contexts
	* are separated from each other too.]
	*
	* The following field is used to detect when we cross into an
	* interrupt context:
	*/
	unsigned int irq_context:2; /* bit 0 - soft, bit 1 - hard */
	unsigned int trylock:1; /* 16 bits */

	unsigned int read:2; /* see lock_acquire() comment */
	unsigned int check:2; /* see lock_acquire() comment */
	unsigned int hardirqs_off:1;
	unsigned int references:11; /* 32 bits */
	};

	/*
	* Initialization, self-test and debugging-output methods:
	*/
	extern void lockdep_init(void);
	extern void lockdep_info(void);
	extern void lockdep_reset(void);
	extern void lockdep_reset_lock(struct lockdep_map *lock);
	extern void lockdep_free_key_range(void *start, unsigned long size);
	extern void lockdep_sys_exit(void);

	extern void lockdep_off(void);
	extern void lockdep_on(void);

	/*
	* These methods are used by specific locking variants (spinlocks,
	* rwlocks, mutexes and rwsems) to pass init/acquire/release events
	* to lockdep:
	*/

	extern void lockdep_init_map(struct lockdep_map lock, const char name,
	struct lock_class_key *key, int subclass);

	/*
	* To initialize a lockdep_map statically use this macro.
	* Note that _name must not be NULL.
	*/
	#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
	{ .name = (_name), .key = (void *)(_key), }

	/*
	* Reinitialize a lock key - for cases where there is special locking or
	* special initialization of locks so that the validator gets the scope
	* of dependencies wrong: they are either too broad (they need a class-split)
	* or they are too narrow (they suffer from a false class-split):
	*/
	#define lockdep_set_class(lock, key) \
	lockdep_init_map(&(lock)->dep_map, #key, key, 0)
	#define lockdep_set_class_and_name(lock, key, name) \
	lockdep_init_map(&(lock)->dep_map, name, key, 0)
	#define lockdep_set_class_and_subclass(lock, key, sub) \
	lockdep_init_map(&(lock)->dep_map, #key, key, sub)
	#define lockdep_set_subclass(lock, sub) \
	lockdep_init_map(&(lock)->dep_map, #lock, \
	(lock)->dep_map.key, sub)

	#define lockdep_set_novalidate_class(lock) \
	lockdep_set_class(lock, &__lockdep_no_validate__)
	/*
	* Compare locking classes
	*/
	#define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)

	static inline int lockdep_match_key(struct lockdep_map *lock,
	struct lock_class_key *key)
	{
	return lock->key == key;
	}

	/*
	* Acquire a lock.
	*
	* Values for "read":
	*
	* 0: exclusive (write) acquire
	* 1: read-acquire (no recursion allowed)
	* 2: read-acquire with same-instance recursion allowed
	*
	* Values for check:
	*
	* 0: disabled
	* 1: simple checks (freeing, held-at-exit-time, etc.)
	* 2: full validation
	*/
	extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
	int trylock, int read, int check,
	struct lockdep_map *nest_lock, unsigned long ip);

	extern void lock_release(struct lockdep_map *lock, int nested,
	unsigned long ip);

	#define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)

	extern int lock_is_held(struct lockdep_map *lock);

	extern void lock_set_class(struct lockdep_map lock, const char name,
	struct lock_class_key *key, unsigned int subclass,
	unsigned long ip);

	static inline void lock_set_subclass(struct lockdep_map *lock,
	unsigned int subclass, unsigned long ip)
	{
	lock_set_class(lock, lock->name, lock->key, subclass, ip);
	}

	extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
	extern void lockdep_clear_current_reclaim_state(void);
	extern void lockdep_trace_alloc(gfp_t mask);

	# define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0,

	#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)

	#define lockdep_assert_held(l) WARN_ON(debug_locks && !lockdep_is_held(l))

	#else /* !LOCKDEP */

	static inline void lockdep_off(void)
	{
	}

	static inline void lockdep_on(void)
	{
	}

	# define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
	# define lock_release(l, n, i) do { } while (0)
	# define lock_set_class(l, n, k, s, i) do { } while (0)
	# define lock_set_subclass(l, s, i) do { } while (0)
	# define lockdep_set_current_reclaim_state(g) do { } while (0)
	# define lockdep_clear_current_reclaim_state() do { } while (0)
	# define lockdep_trace_alloc(g) do { } while (0)
	# define lockdep_init() do { } while (0)
	# define lockdep_info() do { } while (0)
	# define lockdep_init_map(lock, name, key, sub) \
	do { (void)(name); (void)(key); } while (0)
	# define lockdep_set_class(lock, key) do { (void)(key); } while (0)
	# define lockdep_set_class_and_name(lock, key, name) \
	do { (void)(key); (void)(name); } while (0)
	#define lockdep_set_class_and_subclass(lock, key, sub) \
	do { (void)(key); } while (0)
	#define lockdep_set_subclass(lock, sub) do { } while (0)

	#define lockdep_set_novalidate_class(lock) do { } while (0)

	/*
	* We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
	* case since the result is not well defined and the caller should rather
	* #ifdef the call himself.
	*/

	# define INIT_LOCKDEP
	# define lockdep_reset() do { debug_locks = 1; } while (0)
	# define lockdep_free_key_range(start, size) do { } while (0)
	# define lockdep_sys_exit() do { } while (0)
	/*
	* The class key takes no space if lockdep is disabled:
	*/
	struct lock_class_key { };

	#define lockdep_depth(tsk) (0)

	#define lockdep_assert_held(l) do { } while (0)

	#endif /* !LOCKDEP */

	#ifdef CONFIG_LOCK_STAT

	extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
	extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);

	#define LOCK_CONTENDED(_lock, try, lock) \
	do { \
	if (!try(_lock)) { \
	lock_contended(&(_lock)->dep_map, _RET_IP_); \
	lock(_lock); \
	} \
	lock_acquired(&(_lock)->dep_map, _RET_IP_); \
	} while (0)

	#else /* CONFIG_LOCK_STAT */

	#define lock_contended(lockdep_map, ip) do {} while (0)
	#define lock_acquired(lockdep_map, ip) do {} while (0)

	#define LOCK_CONTENDED(_lock, try, lock) \
	lock(_lock)

	#endif /* CONFIG_LOCK_STAT */

	#ifdef CONFIG_LOCKDEP

	/*
	* On lockdep we dont want the hand-coded irq-enable of
	* _raw_*_lock_flags() code, because lockdep assumes
	* that interrupts are not re-enabled during lock-acquire:
	*/
	#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
	LOCK_CONTENDED((_lock), (try), (lock))

	#else /* CONFIG_LOCKDEP */

	#define LOCK_CONTENDED_FLAGS(_lock, try, lock, lockfl, flags) \
	lockfl((_lock), (flags))

	#endif /* CONFIG_LOCKDEP */

	#ifdef CONFIG_TRACE_IRQFLAGS
	extern void print_irqtrace_events(struct task_struct *curr);
	#else
	static inline void print_irqtrace_events(struct task_struct *curr)
	{
	}
	#endif

	/*
	* For trivial one-depth nesting of a lock-class, the following
	* global define can be used. (Subsystems with multiple levels
	* of nesting should define their own lock-nesting subclasses.)
	*/
	#define SINGLE_DEPTH_NESTING 1

	/*
	* Map the dependency ops to NOP or to real lockdep ops, depending
	* on the per lock-class debug mode:
	*/

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	# ifdef CONFIG_PROVE_LOCKING
	# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
	# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
	# else
	# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
	# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, NULL, i)
	# endif
	# define spin_release(l, n, i) lock_release(l, n, i)
	#else
	# define spin_acquire(l, s, t, i) do { } while (0)
	# define spin_release(l, n, i) do { } while (0)
	#endif

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	# ifdef CONFIG_PROVE_LOCKING
	# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
	# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, NULL, i)
	# else
	# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
	# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, NULL, i)
	# endif
	# define rwlock_release(l, n, i) lock_release(l, n, i)
	#else
	# define rwlock_acquire(l, s, t, i) do { } while (0)
	# define rwlock_acquire_read(l, s, t, i) do { } while (0)
	# define rwlock_release(l, n, i) do { } while (0)
	#endif

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	# ifdef CONFIG_PROVE_LOCKING
	# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
	# else
	# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
	# endif
	# define mutex_release(l, n, i) lock_release(l, n, i)
	#else
	# define mutex_acquire(l, s, t, i) do { } while (0)
	# define mutex_release(l, n, i) do { } while (0)
	#endif

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	# ifdef CONFIG_PROVE_LOCKING
	# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
	# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, NULL, i)
	# else
	# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
	# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, NULL, i)
	# endif
	# define rwsem_release(l, n, i) lock_release(l, n, i)
	#else
	# define rwsem_acquire(l, s, t, i) do { } while (0)
	# define rwsem_acquire_read(l, s, t, i) do { } while (0)
	# define rwsem_release(l, n, i) do { } while (0)
	#endif

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	# ifdef CONFIG_PROVE_LOCKING
	# define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
	# else
	# define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
	# endif
	# define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
	#else
	# define lock_map_acquire(l) do { } while (0)
	# define lock_map_release(l) do { } while (0)
	#endif

	#ifdef CONFIG_PROVE_LOCKING
	# define might_lock(lock) \
	do { \
	typecheck(struct lockdep_map *, &(lock)->dep_map); \
	lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_); \
	lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
	} while (0)
	# define might_lock_read(lock) \
	do { \
	typecheck(struct lockdep_map *, &(lock)->dep_map); \
	lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_); \
	lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
	} while (0)
	#else
	# define might_lock(lock) do { } while (0)
	# define might_lock_read(lock) do { } while (0)
	#endif

	#ifdef CONFIG_PROVE_RCU
	extern void lockdep_rcu_dereference(const char *file, const int line);
	#endif

	#endif /* __LINUX_LOCKDEP_H */