/*
 * 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;

#ifdef CONFIG_LOCKDEP

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

/*
 * Lock-class usage-state bits:
 */
enum lock_usage_bit
{
        LOCK_USED = 0,
        LOCK_USED_IN_HARDIRQ,
        LOCK_USED_IN_SOFTIRQ,
        LOCK_ENABLED_SOFTIRQS,
        LOCK_ENABLED_HARDIRQS,
        LOCK_USED_IN_HARDIRQ_READ,
        LOCK_USED_IN_SOFTIRQ_READ,
        LOCK_ENABLED_SOFTIRQS_READ,
        LOCK_ENABLED_HARDIRQS_READ,
        LOCK_USAGE_STATES
};

/*
 * Usage-state bitmasks:
 */
#define LOCKF_USED                      (1 << LOCK_USED)
#define LOCKF_USED_IN_HARDIRQ           (1 << LOCK_USED_IN_HARDIRQ)
#define LOCKF_USED_IN_SOFTIRQ           (1 << LOCK_USED_IN_SOFTIRQ)
#define LOCKF_ENABLED_HARDIRQS          (1 << LOCK_ENABLED_HARDIRQS)
#define LOCKF_ENABLED_SOFTIRQS          (1 << LOCK_ENABLED_SOFTIRQS)

#define LOCKF_ENABLED_IRQS (LOCKF_ENABLED_HARDIRQS | LOCKF_ENABLED_SOFTIRQS)
#define LOCKF_USED_IN_IRQ (LOCKF_USED_IN_HARDIRQ | LOCKF_USED_IN_SOFTIRQ)

#define LOCKF_USED_IN_HARDIRQ_READ      (1 << LOCK_USED_IN_HARDIRQ_READ)
#define LOCKF_USED_IN_SOFTIRQ_READ      (1 << LOCK_USED_IN_SOFTIRQ_READ)
#define LOCKF_ENABLED_HARDIRQS_READ     (1 << LOCK_ENABLED_HARDIRQS_READ)
#define LOCKF_ENABLED_SOFTIRQS_READ     (1 << LOCK_ENABLED_SOFTIRQS_READ)

#define LOCKF_ENABLED_IRQS_READ \
                (LOCKF_ENABLED_HARDIRQS_READ | LOCKF_ENABLED_SOFTIRQS_READ)
#define LOCKF_USED_IN_IRQ_READ \
                (LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)

#define MAX_LOCKDEP_SUBCLASSES          8UL

/*
 * 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];
};

/*
 * 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;

        /*
         * IRQ/softirq usage tracking bits:
         */
        unsigned long                   usage_mask;
        struct stack_trace              usage_traces[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[4];
#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];
        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;
        const char                      *name;
#ifdef CONFIG_LOCK_STAT
        int                             cpu;
#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;
};

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

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;
        struct lock_class               *class;
        unsigned long                   acquire_ip;
        struct lockdep_map              *instance;

#ifdef CONFIG_LOCK_STAT
        u64                             waittime_stamp;
        u64                             holdtime_stamp;
#endif
        /*
         * 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:
         */
        int                             irq_context;
        int                             trylock;
        int                             read;
        int                             check;
        int                             hardirqs_off;
};

/*
 * 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)

/*
 * 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), }


/*
 * 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, unsigned long ip);

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

# define INIT_LOCKDEP                           .lockdep_recursion = 0,

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

#else /* !LOCKDEP */

static inline void lockdep_off(void)
{
}

static inline void lockdep_on(void)
{
}

# define lock_acquire(l, s, t, r, c, i)         do { } while (0)
# define lock_release(l, n, i)                  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)(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); } 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 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)

#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);

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

#else /* CONFIG_LOCK_STAT */

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

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

#endif /* CONFIG_LOCK_STAT */

#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_GENERIC_HARDIRQS)
extern void early_init_irq_lock_class(void);
#else
static inline void early_init_irq_lock_class(void)
{
}
#endif

#ifdef CONFIG_TRACE_IRQFLAGS
extern void early_boot_irqs_off(void);
extern void early_boot_irqs_on(void);
extern void print_irqtrace_events(struct task_struct *curr);
#else
static inline void early_boot_irqs_off(void)
{
}
static inline void early_boot_irqs_on(void)
{
}
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, i)
# else
#  define spin_acquire(l, s, t, i)              lock_acquire(l, s, t, 0, 1, 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, i)
#  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 2, i)
# else
#  define rwlock_acquire(l, s, t, i)            lock_acquire(l, s, t, 0, 1, i)
#  define rwlock_acquire_read(l, s, t, i)       lock_acquire(l, s, t, 2, 1, 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, i)
# else
#  define mutex_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, 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, i)
#  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 2, i)
# else
#  define rwsem_acquire(l, s, t, i)             lock_acquire(l, s, t, 0, 1, i)
#  define rwsem_acquire_read(l, s, t, i)        lock_acquire(l, s, t, 1, 1, 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

#endif /* __LINUX_LOCKDEP_H */