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32 results

debugobjects.c

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  • debugobjects.c 29.45 KiB
    /*
     * Generic infrastructure for lifetime debugging of objects.
     *
     * Started by Thomas Gleixner
     *
     * Copyright (C) 2008, Thomas Gleixner <tglx@linutronix.de>
     *
     * For licencing details see kernel-base/COPYING
     */
    
    #define pr_fmt(fmt) "ODEBUG: " fmt
    
    #include <linux/debugobjects.h>
    #include <linux/interrupt.h>
    #include <linux/sched.h>
    #include <linux/sched/task_stack.h>
    #include <linux/seq_file.h>
    #include <linux/debugfs.h>
    #include <linux/slab.h>
    #include <linux/hash.h>
    #include <linux/kmemleak.h>
    
    #define ODEBUG_HASH_BITS	14
    #define ODEBUG_HASH_SIZE	(1 << ODEBUG_HASH_BITS)
    
    #define ODEBUG_POOL_SIZE	1024
    #define ODEBUG_POOL_MIN_LEVEL	256
    
    #define ODEBUG_CHUNK_SHIFT	PAGE_SHIFT
    #define ODEBUG_CHUNK_SIZE	(1 << ODEBUG_CHUNK_SHIFT)
    #define ODEBUG_CHUNK_MASK	(~(ODEBUG_CHUNK_SIZE - 1))
    
    struct debug_bucket {
    	struct hlist_head	list;
    	raw_spinlock_t		lock;
    };
    
    static struct debug_bucket	obj_hash[ODEBUG_HASH_SIZE];
    
    static struct debug_obj		obj_static_pool[ODEBUG_POOL_SIZE] __initdata;
    
    static DEFINE_RAW_SPINLOCK(pool_lock);
    
    static HLIST_HEAD(obj_pool);
    static HLIST_HEAD(obj_to_free);
    
    static int			obj_pool_min_free = ODEBUG_POOL_SIZE;
    static int			obj_pool_free = ODEBUG_POOL_SIZE;
    static int			obj_pool_used;
    static int			obj_pool_max_used;
    /* The number of objs on the global free list */
    static int			obj_nr_tofree;
    static struct kmem_cache	*obj_cache;
    
    static int			debug_objects_maxchain __read_mostly;
    static int __maybe_unused	debug_objects_maxchecked __read_mostly;
    static int			debug_objects_fixups __read_mostly;
    static int			debug_objects_warnings __read_mostly;
    static int			debug_objects_enabled __read_mostly
    				= CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;
    static int			debug_objects_pool_size __read_mostly
    				= ODEBUG_POOL_SIZE;
    static int			debug_objects_pool_min_level __read_mostly
    				= ODEBUG_POOL_MIN_LEVEL;
    static struct debug_obj_descr	*descr_test  __read_mostly;
    
    /*
     * Track numbers of kmem_cache_alloc()/free() calls done.
     */
    static int			debug_objects_allocated;
    static int			debug_objects_freed;
    
    static void free_obj_work(struct work_struct *work);
    static DECLARE_WORK(debug_obj_work, free_obj_work);
    
    static int __init enable_object_debug(char *str)
    {
    	debug_objects_enabled = 1;
    	return 0;
    }
    
    static int __init disable_object_debug(char *str)
    {
    	debug_objects_enabled = 0;
    	return 0;
    }
    
    early_param("debug_objects", enable_object_debug);
    early_param("no_debug_objects", disable_object_debug);
    
    static const char *obj_states[ODEBUG_STATE_MAX] = {
    	[ODEBUG_STATE_NONE]		= "none",
    	[ODEBUG_STATE_INIT]		= "initialized",
    	[ODEBUG_STATE_INACTIVE]		= "inactive",
    	[ODEBUG_STATE_ACTIVE]		= "active",
    	[ODEBUG_STATE_DESTROYED]	= "destroyed",
    	[ODEBUG_STATE_NOTAVAILABLE]	= "not available",
    };
    
    static void fill_pool(void)
    {
    	gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
    	struct debug_obj *new, *obj;
    	unsigned long flags;
    
    	if (likely(obj_pool_free >= debug_objects_pool_min_level))
    		return;
    
    	/*
    	 * Reuse objs from the global free list; they will be reinitialized
    	 * when allocating.
    	 */
    	while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {
    		raw_spin_lock_irqsave(&pool_lock, flags);
    		/*
    		 * Recheck with the lock held as the worker thread might have
    		 * won the race and freed the global free list already.
    		 */
    		if (obj_nr_tofree) {
    			obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
    			hlist_del(&obj->node);
    			obj_nr_tofree--;
    			hlist_add_head(&obj->node, &obj_pool);
    			obj_pool_free++;
    		}
    		raw_spin_unlock_irqrestore(&pool_lock, flags);
    	}
    
    	if (unlikely(!obj_cache))
    		return;
    
    	while (obj_pool_free < debug_objects_pool_min_level) {
    
    		new = kmem_cache_zalloc(obj_cache, gfp);
    		if (!new)
    			return;
    
    		kmemleak_ignore(new);
    		raw_spin_lock_irqsave(&pool_lock, flags);
    		hlist_add_head(&new->node, &obj_pool);
    		debug_objects_allocated++;
    		obj_pool_free++;
    		raw_spin_unlock_irqrestore(&pool_lock, flags);
    	}
    }
    
    /*
     * Lookup an object in the hash bucket.
     */
    static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b)
    {
    	struct debug_obj *obj;
    	int cnt = 0;
    
    	hlist_for_each_entry(obj, &b->list, node) {
    		cnt++;
    		if (obj->object == addr)
    			return obj;
    	}
    	if (cnt > debug_objects_maxchain)
    		debug_objects_maxchain = cnt;
    
    	return NULL;
    }
    
    /*
     * Allocate a new object. If the pool is empty, switch off the debugger.
     * Must be called with interrupts disabled.
     */
    static struct debug_obj *
    alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr)
    {
    	struct debug_obj *obj = NULL;
    
    	raw_spin_lock(&pool_lock);
    	if (obj_pool.first) {
    		obj	    = hlist_entry(obj_pool.first, typeof(*obj), node);
    
    		obj->object = addr;
    		obj->descr  = descr;
    		obj->state  = ODEBUG_STATE_NONE;
    		obj->astate = 0;
    		hlist_del(&obj->node);
    
    		hlist_add_head(&obj->node, &b->list);
    
    		obj_pool_used++;
    		if (obj_pool_used > obj_pool_max_used)
    			obj_pool_max_used = obj_pool_used;
    
    		obj_pool_free--;
    		if (obj_pool_free < obj_pool_min_free)
    			obj_pool_min_free = obj_pool_free;
    	}
    	raw_spin_unlock(&pool_lock);
    
    	return obj;
    }
    
    /*
     * workqueue function to free objects.
     *
     * To reduce contention on the global pool_lock, the actual freeing of
     * debug objects will be delayed if the pool_lock is busy.
     */
    static void free_obj_work(struct work_struct *work)
    {
    	struct hlist_node *tmp;
    	struct debug_obj *obj;
    	unsigned long flags;
    	HLIST_HEAD(tofree);
    
    	if (!raw_spin_trylock_irqsave(&pool_lock, flags))
    		return;
    
    	/*
    	 * The objs on the pool list might be allocated before the work is
    	 * run, so recheck if pool list it full or not, if not fill pool
    	 * list from the global free list
    	 */
    	while (obj_nr_tofree && obj_pool_free < debug_objects_pool_size) {
    		obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
    		hlist_del(&obj->node);
    		hlist_add_head(&obj->node, &obj_pool);
    		obj_pool_free++;
    		obj_nr_tofree--;
    	}
    
    	/*
    	 * Pool list is already full and there are still objs on the free
    	 * list. Move remaining free objs to a temporary list to free the
    	 * memory outside the pool_lock held region.
    	 */
    	if (obj_nr_tofree) {
    		hlist_move_list(&obj_to_free, &tofree);
    		debug_objects_freed += obj_nr_tofree;
    		obj_nr_tofree = 0;
    	}
    	raw_spin_unlock_irqrestore(&pool_lock, flags);
    
    	hlist_for_each_entry_safe(obj, tmp, &tofree, node) {
    		hlist_del(&obj->node);
    		kmem_cache_free(obj_cache, obj);
    	}
    }
    
    static bool __free_object(struct debug_obj *obj)
    {
    	unsigned long flags;
    	bool work;
    
    	raw_spin_lock_irqsave(&pool_lock, flags);
    	work = (obj_pool_free > debug_objects_pool_size) && obj_cache;
    	obj_pool_used--;
    
    	if (work) {
    		obj_nr_tofree++;
    		hlist_add_head(&obj->node, &obj_to_free);
    	} else {
    		obj_pool_free++;
    		hlist_add_head(&obj->node, &obj_pool);
    	}
    	raw_spin_unlock_irqrestore(&pool_lock, flags);
    	return work;
    }
    
    /*
     * Put the object back into the pool and schedule work to free objects
     * if necessary.
     */
    static void free_object(struct debug_obj *obj)
    {
    	if (__free_object(obj))
    		schedule_work(&debug_obj_work);
    }
    
    /*
     * We run out of memory. That means we probably have tons of objects
     * allocated.
     */
    static void debug_objects_oom(void)
    {
    	struct debug_bucket *db = obj_hash;
    	struct hlist_node *tmp;
    	HLIST_HEAD(freelist);
    	struct debug_obj *obj;
    	unsigned long flags;
    	int i;
    
    	pr_warn("Out of memory. ODEBUG disabled\n");
    
    	for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
    		raw_spin_lock_irqsave(&db->lock, flags);
    		hlist_move_list(&db->list, &freelist);
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    
    		/* Now free them */
    		hlist_for_each_entry_safe(obj, tmp, &freelist, node) {
    			hlist_del(&obj->node);
    			free_object(obj);
    		}
    	}
    }
    
    /*
     * We use the pfn of the address for the hash. That way we can check
     * for freed objects simply by checking the affected bucket.
     */
    static struct debug_bucket *get_bucket(unsigned long addr)
    {
    	unsigned long hash;
    
    	hash = hash_long((addr >> ODEBUG_CHUNK_SHIFT), ODEBUG_HASH_BITS);
    	return &obj_hash[hash];
    }
    
    static void debug_print_object(struct debug_obj *obj, char *msg)
    {
    	struct debug_obj_descr *descr = obj->descr;
    	static int limit;
    
    	if (limit < 5 && descr != descr_test) {
    		void *hint = descr->debug_hint ?
    			descr->debug_hint(obj->object) : NULL;
    		limit++;
    		WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
    				 "object type: %s hint: %pS\n",
    			msg, obj_states[obj->state], obj->astate,
    			descr->name, hint);
    	}
    	debug_objects_warnings++;
    }
    
    /*
     * Try to repair the damage, so we have a better chance to get useful
     * debug output.
     */
    static bool
    debug_object_fixup(bool (*fixup)(void *addr, enum debug_obj_state state),
    		   void * addr, enum debug_obj_state state)
    {
    	if (fixup && fixup(addr, state)) {
    		debug_objects_fixups++;
    		return true;
    	}
    	return false;
    }
    
    static void debug_object_is_on_stack(void *addr, int onstack)
    {
    	int is_on_stack;
    	static int limit;
    
    	if (limit > 4)
    		return;
    
    	is_on_stack = object_is_on_stack(addr);
    	if (is_on_stack == onstack)
    		return;
    
    	limit++;
    	if (is_on_stack)
    		pr_warn("object is on stack, but not annotated\n");
    	else
    		pr_warn("object is not on stack, but annotated\n");
    	WARN_ON(1);
    }
    
    static void
    __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
    {
    	enum debug_obj_state state;
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	fill_pool();
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (!obj) {
    		obj = alloc_object(addr, db, descr);
    		if (!obj) {
    			debug_objects_enabled = 0;
    			raw_spin_unlock_irqrestore(&db->lock, flags);
    			debug_objects_oom();
    			return;
    		}
    		debug_object_is_on_stack(addr, onstack);
    	}
    
    	switch (obj->state) {
    	case ODEBUG_STATE_NONE:
    	case ODEBUG_STATE_INIT:
    	case ODEBUG_STATE_INACTIVE:
    		obj->state = ODEBUG_STATE_INIT;
    		break;
    
    	case ODEBUG_STATE_ACTIVE:
    		debug_print_object(obj, "init");
    		state = obj->state;
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		debug_object_fixup(descr->fixup_init, addr, state);
    		return;
    
    	case ODEBUG_STATE_DESTROYED:
    		debug_print_object(obj, "init");
    		break;
    	default:
    		break;
    	}
    
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    
    /**
     * debug_object_init - debug checks when an object is initialized
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_init(void *addr, struct debug_obj_descr *descr)
    {
    	if (!debug_objects_enabled)
    		return;
    
    	__debug_object_init(addr, descr, 0);
    }
    EXPORT_SYMBOL_GPL(debug_object_init);
    
    /**
     * debug_object_init_on_stack - debug checks when an object on stack is
     *				initialized
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr)
    {
    	if (!debug_objects_enabled)
    		return;
    
    	__debug_object_init(addr, descr, 1);
    }
    EXPORT_SYMBOL_GPL(debug_object_init_on_stack);
    
    /**
     * debug_object_activate - debug checks when an object is activated
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     * Returns 0 for success, -EINVAL for check failed.
     */
    int debug_object_activate(void *addr, struct debug_obj_descr *descr)
    {
    	enum debug_obj_state state;
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    	int ret;
    	struct debug_obj o = { .object = addr,
    			       .state = ODEBUG_STATE_NOTAVAILABLE,
    			       .descr = descr };
    
    	if (!debug_objects_enabled)
    		return 0;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (obj) {
    		switch (obj->state) {
    		case ODEBUG_STATE_INIT:
    		case ODEBUG_STATE_INACTIVE:
    			obj->state = ODEBUG_STATE_ACTIVE;
    			ret = 0;
    			break;
    
    		case ODEBUG_STATE_ACTIVE:
    			debug_print_object(obj, "activate");
    			state = obj->state;
    			raw_spin_unlock_irqrestore(&db->lock, flags);
    			ret = debug_object_fixup(descr->fixup_activate, addr, state);
    			return ret ? 0 : -EINVAL;
    
    		case ODEBUG_STATE_DESTROYED:
    			debug_print_object(obj, "activate");
    			ret = -EINVAL;
    			break;
    		default:
    			ret = 0;
    			break;
    		}
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		return ret;
    	}
    
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    	/*
    	 * We are here when a static object is activated. We
    	 * let the type specific code confirm whether this is
    	 * true or not. if true, we just make sure that the
    	 * static object is tracked in the object tracker. If
    	 * not, this must be a bug, so we try to fix it up.
    	 */
    	if (descr->is_static_object && descr->is_static_object(addr)) {
    		/* track this static object */
    		debug_object_init(addr, descr);
    		debug_object_activate(addr, descr);
    	} else {
    		debug_print_object(&o, "activate");
    		ret = debug_object_fixup(descr->fixup_activate, addr,
    					ODEBUG_STATE_NOTAVAILABLE);
    		return ret ? 0 : -EINVAL;
    	}
    	return 0;
    }
    EXPORT_SYMBOL_GPL(debug_object_activate);
    
    /**
     * debug_object_deactivate - debug checks when an object is deactivated
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_deactivate(void *addr, struct debug_obj_descr *descr)
    {
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	if (!debug_objects_enabled)
    		return;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (obj) {
    		switch (obj->state) {
    		case ODEBUG_STATE_INIT:
    		case ODEBUG_STATE_INACTIVE:
    		case ODEBUG_STATE_ACTIVE:
    			if (!obj->astate)
    				obj->state = ODEBUG_STATE_INACTIVE;
    			else
    				debug_print_object(obj, "deactivate");
    			break;
    
    		case ODEBUG_STATE_DESTROYED:
    			debug_print_object(obj, "deactivate");
    			break;
    		default:
    			break;
    		}
    	} else {
    		struct debug_obj o = { .object = addr,
    				       .state = ODEBUG_STATE_NOTAVAILABLE,
    				       .descr = descr };
    
    		debug_print_object(&o, "deactivate");
    	}
    
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    EXPORT_SYMBOL_GPL(debug_object_deactivate);
    
    /**
     * debug_object_destroy - debug checks when an object is destroyed
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_destroy(void *addr, struct debug_obj_descr *descr)
    {
    	enum debug_obj_state state;
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	if (!debug_objects_enabled)
    		return;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (!obj)
    		goto out_unlock;
    
    	switch (obj->state) {
    	case ODEBUG_STATE_NONE:
    	case ODEBUG_STATE_INIT:
    	case ODEBUG_STATE_INACTIVE:
    		obj->state = ODEBUG_STATE_DESTROYED;
    		break;
    	case ODEBUG_STATE_ACTIVE:
    		debug_print_object(obj, "destroy");
    		state = obj->state;
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		debug_object_fixup(descr->fixup_destroy, addr, state);
    		return;
    
    	case ODEBUG_STATE_DESTROYED:
    		debug_print_object(obj, "destroy");
    		break;
    	default:
    		break;
    	}
    out_unlock:
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    EXPORT_SYMBOL_GPL(debug_object_destroy);
    
    /**
     * debug_object_free - debug checks when an object is freed
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_free(void *addr, struct debug_obj_descr *descr)
    {
    	enum debug_obj_state state;
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	if (!debug_objects_enabled)
    		return;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (!obj)
    		goto out_unlock;
    
    	switch (obj->state) {
    	case ODEBUG_STATE_ACTIVE:
    		debug_print_object(obj, "free");
    		state = obj->state;
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		debug_object_fixup(descr->fixup_free, addr, state);
    		return;
    	default:
    		hlist_del(&obj->node);
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		free_object(obj);
    		return;
    	}
    out_unlock:
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    EXPORT_SYMBOL_GPL(debug_object_free);
    
    /**
     * debug_object_assert_init - debug checks when object should be init-ed
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     */
    void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)
    {
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	if (!debug_objects_enabled)
    		return;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (!obj) {
    		struct debug_obj o = { .object = addr,
    				       .state = ODEBUG_STATE_NOTAVAILABLE,
    				       .descr = descr };
    
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    		/*
    		 * Maybe the object is static, and we let the type specific
    		 * code confirm. Track this static object if true, else invoke
    		 * fixup.
    		 */
    		if (descr->is_static_object && descr->is_static_object(addr)) {
    			/* Track this static object */
    			debug_object_init(addr, descr);
    		} else {
    			debug_print_object(&o, "assert_init");
    			debug_object_fixup(descr->fixup_assert_init, addr,
    					   ODEBUG_STATE_NOTAVAILABLE);
    		}
    		return;
    	}
    
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    EXPORT_SYMBOL_GPL(debug_object_assert_init);
    
    /**
     * debug_object_active_state - debug checks object usage state machine
     * @addr:	address of the object
     * @descr:	pointer to an object specific debug description structure
     * @expect:	expected state
     * @next:	state to move to if expected state is found
     */
    void
    debug_object_active_state(void *addr, struct debug_obj_descr *descr,
    			  unsigned int expect, unsigned int next)
    {
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    
    	if (!debug_objects_enabled)
    		return;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (obj) {
    		switch (obj->state) {
    		case ODEBUG_STATE_ACTIVE:
    			if (obj->astate == expect)
    				obj->astate = next;
    			else
    				debug_print_object(obj, "active_state");
    			break;
    
    		default:
    			debug_print_object(obj, "active_state");
    			break;
    		}
    	} else {
    		struct debug_obj o = { .object = addr,
    				       .state = ODEBUG_STATE_NOTAVAILABLE,
    				       .descr = descr };
    
    		debug_print_object(&o, "active_state");
    	}
    
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    }
    EXPORT_SYMBOL_GPL(debug_object_active_state);
    
    #ifdef CONFIG_DEBUG_OBJECTS_FREE
    static void __debug_check_no_obj_freed(const void *address, unsigned long size)
    {
    	unsigned long flags, oaddr, saddr, eaddr, paddr, chunks;
    	struct debug_obj_descr *descr;
    	enum debug_obj_state state;
    	struct debug_bucket *db;
    	struct hlist_node *tmp;
    	struct debug_obj *obj;
    	int cnt, objs_checked = 0;
    	bool work = false;
    
    	saddr = (unsigned long) address;
    	eaddr = saddr + size;
    	paddr = saddr & ODEBUG_CHUNK_MASK;
    	chunks = ((eaddr - paddr) + (ODEBUG_CHUNK_SIZE - 1));
    	chunks >>= ODEBUG_CHUNK_SHIFT;
    
    	for (;chunks > 0; chunks--, paddr += ODEBUG_CHUNK_SIZE) {
    		db = get_bucket(paddr);
    
    repeat:
    		cnt = 0;
    		raw_spin_lock_irqsave(&db->lock, flags);
    		hlist_for_each_entry_safe(obj, tmp, &db->list, node) {
    			cnt++;
    			oaddr = (unsigned long) obj->object;
    			if (oaddr < saddr || oaddr >= eaddr)
    				continue;
    
    			switch (obj->state) {
    			case ODEBUG_STATE_ACTIVE:
    				debug_print_object(obj, "free");
    				descr = obj->descr;
    				state = obj->state;
    				raw_spin_unlock_irqrestore(&db->lock, flags);
    				debug_object_fixup(descr->fixup_free,
    						   (void *) oaddr, state);
    				goto repeat;
    			default:
    				hlist_del(&obj->node);
    				work |= __free_object(obj);
    				break;
    			}
    		}
    		raw_spin_unlock_irqrestore(&db->lock, flags);
    
    		if (cnt > debug_objects_maxchain)
    			debug_objects_maxchain = cnt;
    
    		objs_checked += cnt;
    	}
    
    	if (objs_checked > debug_objects_maxchecked)
    		debug_objects_maxchecked = objs_checked;
    
    	/* Schedule work to actually kmem_cache_free() objects */
    	if (work)
    		schedule_work(&debug_obj_work);
    }
    
    void debug_check_no_obj_freed(const void *address, unsigned long size)
    {
    	if (debug_objects_enabled)
    		__debug_check_no_obj_freed(address, size);
    }
    #endif
    
    #ifdef CONFIG_DEBUG_FS
    
    static int debug_stats_show(struct seq_file *m, void *v)
    {
    	seq_printf(m, "max_chain     :%d\n", debug_objects_maxchain);
    	seq_printf(m, "max_checked   :%d\n", debug_objects_maxchecked);
    	seq_printf(m, "warnings      :%d\n", debug_objects_warnings);
    	seq_printf(m, "fixups        :%d\n", debug_objects_fixups);
    	seq_printf(m, "pool_free     :%d\n", obj_pool_free);
    	seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);
    	seq_printf(m, "pool_used     :%d\n", obj_pool_used);
    	seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);
    	seq_printf(m, "on_free_list  :%d\n", obj_nr_tofree);
    	seq_printf(m, "objs_allocated:%d\n", debug_objects_allocated);
    	seq_printf(m, "objs_freed    :%d\n", debug_objects_freed);
    	return 0;
    }
    
    static int debug_stats_open(struct inode *inode, struct file *filp)
    {
    	return single_open(filp, debug_stats_show, NULL);
    }
    
    static const struct file_operations debug_stats_fops = {
    	.open		= debug_stats_open,
    	.read		= seq_read,
    	.llseek		= seq_lseek,
    	.release	= single_release,
    };
    
    static int __init debug_objects_init_debugfs(void)
    {
    	struct dentry *dbgdir, *dbgstats;
    
    	if (!debug_objects_enabled)
    		return 0;
    
    	dbgdir = debugfs_create_dir("debug_objects", NULL);
    	if (!dbgdir)
    		return -ENOMEM;
    
    	dbgstats = debugfs_create_file("stats", 0444, dbgdir, NULL,
    				       &debug_stats_fops);
    	if (!dbgstats)
    		goto err;
    
    	return 0;
    
    err:
    	debugfs_remove(dbgdir);
    
    	return -ENOMEM;
    }
    __initcall(debug_objects_init_debugfs);
    
    #else
    static inline void debug_objects_init_debugfs(void) { }
    #endif
    
    #ifdef CONFIG_DEBUG_OBJECTS_SELFTEST
    
    /* Random data structure for the self test */
    struct self_test {
    	unsigned long	dummy1[6];
    	int		static_init;
    	unsigned long	dummy2[3];
    };
    
    static __initdata struct debug_obj_descr descr_type_test;
    
    static bool __init is_static_object(void *addr)
    {
    	struct self_test *obj = addr;
    
    	return obj->static_init;
    }
    
    /*
     * fixup_init is called when:
     * - an active object is initialized
     */
    static bool __init fixup_init(void *addr, enum debug_obj_state state)
    {
    	struct self_test *obj = addr;
    
    	switch (state) {
    	case ODEBUG_STATE_ACTIVE:
    		debug_object_deactivate(obj, &descr_type_test);
    		debug_object_init(obj, &descr_type_test);
    		return true;
    	default:
    		return false;
    	}
    }
    
    /*
     * fixup_activate is called when:
     * - an active object is activated
     * - an unknown non-static object is activated
     */
    static bool __init fixup_activate(void *addr, enum debug_obj_state state)
    {
    	struct self_test *obj = addr;
    
    	switch (state) {
    	case ODEBUG_STATE_NOTAVAILABLE:
    		return true;
    	case ODEBUG_STATE_ACTIVE:
    		debug_object_deactivate(obj, &descr_type_test);
    		debug_object_activate(obj, &descr_type_test);
    		return true;
    
    	default:
    		return false;
    	}
    }
    
    /*
     * fixup_destroy is called when:
     * - an active object is destroyed
     */
    static bool __init fixup_destroy(void *addr, enum debug_obj_state state)
    {
    	struct self_test *obj = addr;
    
    	switch (state) {
    	case ODEBUG_STATE_ACTIVE:
    		debug_object_deactivate(obj, &descr_type_test);
    		debug_object_destroy(obj, &descr_type_test);
    		return true;
    	default:
    		return false;
    	}
    }
    
    /*
     * fixup_free is called when:
     * - an active object is freed
     */
    static bool __init fixup_free(void *addr, enum debug_obj_state state)
    {
    	struct self_test *obj = addr;
    
    	switch (state) {
    	case ODEBUG_STATE_ACTIVE:
    		debug_object_deactivate(obj, &descr_type_test);
    		debug_object_free(obj, &descr_type_test);
    		return true;
    	default:
    		return false;
    	}
    }
    
    static int __init
    check_results(void *addr, enum debug_obj_state state, int fixups, int warnings)
    {
    	struct debug_bucket *db;
    	struct debug_obj *obj;
    	unsigned long flags;
    	int res = -EINVAL;
    
    	db = get_bucket((unsigned long) addr);
    
    	raw_spin_lock_irqsave(&db->lock, flags);
    
    	obj = lookup_object(addr, db);
    	if (!obj && state != ODEBUG_STATE_NONE) {
    		WARN(1, KERN_ERR "ODEBUG: selftest object not found\n");
    		goto out;
    	}
    	if (obj && obj->state != state) {
    		WARN(1, KERN_ERR "ODEBUG: selftest wrong state: %d != %d\n",
    		       obj->state, state);
    		goto out;
    	}
    	if (fixups != debug_objects_fixups) {
    		WARN(1, KERN_ERR "ODEBUG: selftest fixups failed %d != %d\n",
    		       fixups, debug_objects_fixups);
    		goto out;
    	}
    	if (warnings != debug_objects_warnings) {
    		WARN(1, KERN_ERR "ODEBUG: selftest warnings failed %d != %d\n",
    		       warnings, debug_objects_warnings);
    		goto out;
    	}
    	res = 0;
    out:
    	raw_spin_unlock_irqrestore(&db->lock, flags);
    	if (res)
    		debug_objects_enabled = 0;
    	return res;
    }
    
    static __initdata struct debug_obj_descr descr_type_test = {
    	.name			= "selftest",
    	.is_static_object	= is_static_object,
    	.fixup_init		= fixup_init,
    	.fixup_activate		= fixup_activate,
    	.fixup_destroy		= fixup_destroy,
    	.fixup_free		= fixup_free,
    };
    
    static __initdata struct self_test obj = { .static_init = 0 };
    
    static void __init debug_objects_selftest(void)
    {
    	int fixups, oldfixups, warnings, oldwarnings;
    	unsigned long flags;
    
    	local_irq_save(flags);
    
    	fixups = oldfixups = debug_objects_fixups;
    	warnings = oldwarnings = debug_objects_warnings;
    	descr_test = &descr_type_test;
    
    	debug_object_init(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
    		goto out;
    	debug_object_activate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
    		goto out;
    	debug_object_activate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_ACTIVE, ++fixups, ++warnings))
    		goto out;
    	debug_object_deactivate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_INACTIVE, fixups, warnings))
    		goto out;
    	debug_object_destroy(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, warnings))
    		goto out;
    	debug_object_init(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
    		goto out;
    	debug_object_activate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
    		goto out;
    	debug_object_deactivate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
    		goto out;
    	debug_object_free(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
    		goto out;
    
    	obj.static_init = 1;
    	debug_object_activate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
    		goto out;
    	debug_object_init(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_INIT, ++fixups, ++warnings))
    		goto out;
    	debug_object_free(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
    		goto out;
    
    #ifdef CONFIG_DEBUG_OBJECTS_FREE
    	debug_object_init(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
    		goto out;
    	debug_object_activate(&obj, &descr_type_test);
    	if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
    		goto out;
    	__debug_check_no_obj_freed(&obj, sizeof(obj));
    	if (check_results(&obj, ODEBUG_STATE_NONE, ++fixups, ++warnings))
    		goto out;
    #endif
    	pr_info("selftest passed\n");
    
    out:
    	debug_objects_fixups = oldfixups;
    	debug_objects_warnings = oldwarnings;
    	descr_test = NULL;
    
    	local_irq_restore(flags);
    }
    #else
    static inline void debug_objects_selftest(void) { }
    #endif
    
    /*
     * Called during early boot to initialize the hash buckets and link
     * the static object pool objects into the poll list. After this call
     * the object tracker is fully operational.
     */
    void __init debug_objects_early_init(void)
    {
    	int i;
    
    	for (i = 0; i < ODEBUG_HASH_SIZE; i++)
    		raw_spin_lock_init(&obj_hash[i].lock);
    
    	for (i = 0; i < ODEBUG_POOL_SIZE; i++)
    		hlist_add_head(&obj_static_pool[i].node, &obj_pool);
    }
    
    /*
     * Convert the statically allocated objects to dynamic ones:
     */
    static int __init debug_objects_replace_static_objects(void)
    {
    	struct debug_bucket *db = obj_hash;
    	struct hlist_node *tmp;
    	struct debug_obj *obj, *new;
    	HLIST_HEAD(objects);
    	int i, cnt = 0;
    
    	for (i = 0; i < ODEBUG_POOL_SIZE; i++) {
    		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
    		if (!obj)
    			goto free;
    		kmemleak_ignore(obj);
    		hlist_add_head(&obj->node, &objects);
    	}
    
    	/*
    	 * When debug_objects_mem_init() is called we know that only
    	 * one CPU is up, so disabling interrupts is enough
    	 * protection. This avoids the lockdep hell of lock ordering.
    	 */
    	local_irq_disable();
    
    	/* Remove the statically allocated objects from the pool */
    	hlist_for_each_entry_safe(obj, tmp, &obj_pool, node)
    		hlist_del(&obj->node);
    	/* Move the allocated objects to the pool */
    	hlist_move_list(&objects, &obj_pool);
    
    	/* Replace the active object references */
    	for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
    		hlist_move_list(&db->list, &objects);
    
    		hlist_for_each_entry(obj, &objects, node) {
    			new = hlist_entry(obj_pool.first, typeof(*obj), node);
    			hlist_del(&new->node);
    			/* copy object data */
    			*new = *obj;
    			hlist_add_head(&new->node, &db->list);
    			cnt++;
    		}
    	}
    	local_irq_enable();
    
    	pr_debug("%d of %d active objects replaced\n",
    		 cnt, obj_pool_used);
    	return 0;
    free:
    	hlist_for_each_entry_safe(obj, tmp, &objects, node) {
    		hlist_del(&obj->node);
    		kmem_cache_free(obj_cache, obj);
    	}
    	return -ENOMEM;
    }
    
    /*
     * Called after the kmem_caches are functional to setup a dedicated
     * cache pool, which has the SLAB_DEBUG_OBJECTS flag set. This flag
     * prevents that the debug code is called on kmem_cache_free() for the
     * debug tracker objects to avoid recursive calls.
     */
    void __init debug_objects_mem_init(void)
    {
    	if (!debug_objects_enabled)
    		return;
    
    	obj_cache = kmem_cache_create("debug_objects_cache",
    				      sizeof (struct debug_obj), 0,
    				      SLAB_DEBUG_OBJECTS, NULL);
    
    	if (!obj_cache || debug_objects_replace_static_objects()) {
    		debug_objects_enabled = 0;
    		if (obj_cache)
    			kmem_cache_destroy(obj_cache);
    		pr_warn("out of memory.\n");
    	} else
    		debug_objects_selftest();
    
    	/*
    	 * Increase the thresholds for allocating and freeing objects
    	 * according to the number of possible CPUs available in the system.
    	 */
    	debug_objects_pool_size += num_possible_cpus() * 32;
    	debug_objects_pool_min_level += num_possible_cpus() * 4;
    }