root/include/linux/lockdep.h

INCLUDED FROM

DEFINITIONS

1. lockdep_copy_map
2. lockdep_match_key
3. lock_set_subclass
4. lockdep_off
5. lockdep_on
6. print_irqtrace_events

/*
 * 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/locking/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
};

static inline void lockdep_copy_map(struct lockdep_map *to,
                                    struct lockdep_map *from)
{
        int i;

        *to = *from;
        /*
         * Since the class cache can be modified concurrently we could observe
         * half pointers (64bit arch using 32bit copy insns). Therefore clear
         * the caches and take the performance hit.
         *
         * XXX it doesn't work well with lockdep_set_class_and_subclass(), since
         *     that relies on cache abuse.
         */
        for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
                to->class_cache[i] = NULL;
}

/*
 * 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:1;       /* see lock_acquire() comment */
        unsigned int hardirqs_off:1;
        unsigned int references:12;                                     /* 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 asmlinkage 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_and_name(lock, &__lockdep_no_validate__, #lock)
/*
 * 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: simple checks (freeing, held-at-exit-time, etc.)
 *   1: 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)  do {                            \
                WARN_ON(debug_locks && !lockdep_is_held(l));    \
        } while (0)

#define lockdep_assert_held_once(l)     do {                            \
                WARN_ON_ONCE(debug_locks && !lockdep_is_held(l));       \
        } while (0)

#define lockdep_recursing(tsk)  ((tsk)->lockdep_recursion)

#else /* !CONFIG_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 { (void)(l); } while (0)
#define lockdep_assert_held_once(l)             do { (void)(l); } while (0)

#define lockdep_recursing(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, 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:
 */

#define lock_acquire_exclusive(l, s, t, n, i)           lock_acquire(l, s, t, 0, 1, n, i)
#define lock_acquire_shared(l, s, t, n, i)              lock_acquire(l, s, t, 1, 1, n, i)
#define lock_acquire_shared_recursive(l, s, t, n, i)    lock_acquire(l, s, t, 2, 1, n, i)

#define spin_acquire(l, s, t, i)                lock_acquire_exclusive(l, s, t, NULL, i)
#define spin_acquire_nest(l, s, t, n, i)        lock_acquire_exclusive(l, s, t, n, i)
#define spin_release(l, n, i)                   lock_release(l, n, i)

#define rwlock_acquire(l, s, t, i)              lock_acquire_exclusive(l, s, t, NULL, i)
#define rwlock_acquire_read(l, s, t, i)         lock_acquire_shared_recursive(l, s, t, NULL, i)
#define rwlock_release(l, n, i)                 lock_release(l, n, i)

#define seqcount_acquire(l, s, t, i)            lock_acquire_exclusive(l, s, t, NULL, i)
#define seqcount_acquire_read(l, s, t, i)       lock_acquire_shared_recursive(l, s, t, NULL, i)
#define seqcount_release(l, n, i)               lock_release(l, n, i)

#define mutex_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
#define mutex_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
#define mutex_release(l, n, i)                  lock_release(l, n, i)

#define rwsem_acquire(l, s, t, i)               lock_acquire_exclusive(l, s, t, NULL, i)
#define rwsem_acquire_nest(l, s, t, n, i)       lock_acquire_exclusive(l, s, t, n, i)
#define rwsem_acquire_read(l, s, t, i)          lock_acquire_shared(l, s, t, NULL, i)
#define rwsem_release(l, n, i)                  lock_release(l, n, i)

#define lock_map_acquire(l)                     lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
#define lock_map_acquire_read(l)                lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
#define lock_map_acquire_tryread(l)             lock_acquire_shared_recursive(l, 0, 1, NULL, _THIS_IP_)
#define lock_map_release(l)                     lock_release(l, 1, _THIS_IP_)

#ifdef CONFIG_PROVE_LOCKING
# define might_lock(lock)                                               \
do {                                                                    \
        typecheck(struct lockdep_map *, &(lock)->dep_map);              \
        lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, 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, 1, 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
void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
#endif

#endif /* __LINUX_LOCKDEP_H */