lockdep.h

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/*
 * Runtime locking correctness validator
 *
 *  Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <[email protected]>
 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <[email protected]>
 *
 * 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
};

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: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))

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

#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)

#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:
 */

#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)
#  define mutex_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# else
#  define mutex_acquire(l, s, t, i)     lock_acquire(l, s, t, 0, 1, NULL, i)
#  define mutex_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, 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_acquire_nest(l, s, t, n, 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_)
#  define lock_map_acquire_read(l)  lock_acquire(l, 0, 0, 2, 2, NULL, _THIS_IP_)
# else
#  define lock_map_acquire(l)       lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
#  define lock_map_acquire_read(l)  lock_acquire(l, 0, 0, 2, 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_acquire_read(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
void lockdep_rcu_suspicious(const char *file, const int line, const char *s);
#endif

#endif /* __LINUX_LOCKDEP_H */