/*
   * 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_POOL_PERCPU_SIZE	64

  #define ODEBUG_BATCH_SIZE	16

  
  #define ODEBUG_CHUNK_SHIFT	PAGE_SHIFT
  #define ODEBUG_CHUNK_SIZE	(1 << ODEBUG_CHUNK_SHIFT)
  #define ODEBUG_CHUNK_MASK	(~(ODEBUG_CHUNK_SIZE - 1))

  /*
   * We limit the freeing of debug objects via workqueue at a maximum
   * frequency of 10Hz and about 1024 objects for each freeing operation.
   * So it is freeing at most 10k debug objects per second.
   */
  #define ODEBUG_FREE_WORK_MAX	1024
  #define ODEBUG_FREE_WORK_DELAY	DIV_ROUND_UP(HZ, 10)

  struct debug_bucket {
  	struct hlist_head	list;

  	raw_spinlock_t		lock;

  };

  /*
   * Debug object percpu free list
   * Access is protected by disabling irq
   */
  struct debug_percpu_free {
  	struct hlist_head	free_objs;
  	int			obj_free;
  };
  
  static DEFINE_PER_CPU(struct debug_percpu_free, percpu_obj_pool);

  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);

  /*
   * Because of the presence of percpu free pools, obj_pool_free will
   * under-count those in the percpu free pools. Similarly, obj_pool_used
   * will over-count those in the percpu free pools. Adjustments will be
   * made at debug_stats_show(). Both obj_pool_min_free and obj_pool_max_used
   * can be off.
   */

  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;

  static bool			obj_freeing;

  /* The number of objs on the global free list */
  static int			obj_nr_tofree;

  
  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;

  static struct kmem_cache	*obj_cache __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_DELAYED_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 *obj;

  	unsigned long flags;

  	if (likely(READ_ONCE(obj_pool_free) >= debug_objects_pool_min_level))

  		return;

  	/*
  	 * Reuse objs from the global free list; they will be reinitialized
  	 * when allocating.

  	 *
  	 * Both obj_nr_tofree and obj_pool_free are checked locklessly; the
  	 * READ_ONCE()s pair with the WRITE_ONCE()s in pool_lock critical
  	 * sections.

  	 */

  	while (READ_ONCE(obj_nr_tofree) && (READ_ONCE(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.
  		 */

  		while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {

  			obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
  			hlist_del(&obj->node);

  			WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);

  			hlist_add_head(&obj->node, &obj_pool);

  			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

  		}
  		raw_spin_unlock_irqrestore(&pool_lock, flags);
  	}

  	if (unlikely(!obj_cache))

  		return;

  	while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {

  		struct debug_obj *new[ODEBUG_BATCH_SIZE];
  		int cnt;

  		for (cnt = 0; cnt < ODEBUG_BATCH_SIZE; cnt++) {
  			new[cnt] = kmem_cache_zalloc(obj_cache, gfp);
  			if (!new[cnt])
  				break;
  		}
  		if (!cnt)

  			return;

  		raw_spin_lock_irqsave(&pool_lock, flags);

  		while (cnt) {
  			hlist_add_head(&new[--cnt]->node, &obj_pool);
  			debug_objects_allocated++;

  			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

  		}

  		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 from the hlist
   */
  static struct debug_obj *__alloc_object(struct hlist_head *list)
  {
  	struct debug_obj *obj = NULL;
  
  	if (list->first) {
  		obj = hlist_entry(list->first, typeof(*obj), node);
  		hlist_del(&obj->node);
  	}
  
  	return obj;
  }
  
  /*

   * 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_percpu_free *percpu_pool = this_cpu_ptr(&percpu_obj_pool);

  	struct debug_obj *obj;

  	if (likely(obj_cache)) {

  		obj = __alloc_object(&percpu_pool->free_objs);
  		if (obj) {
  			percpu_pool->obj_free--;
  			goto init_obj;
  		}
  	}

  	raw_spin_lock(&pool_lock);
  	obj = __alloc_object(&obj_pool);
  	if (obj) {

  		obj_pool_used++;

  		WRITE_ONCE(obj_pool_free, obj_pool_free - 1);

  
  		/*
  		 * Looking ahead, allocate one batch of debug objects and
  		 * put them into the percpu free pool.
  		 */
  		if (likely(obj_cache)) {
  			int i;
  
  			for (i = 0; i < ODEBUG_BATCH_SIZE; i++) {
  				struct debug_obj *obj2;
  
  				obj2 = __alloc_object(&obj_pool);
  				if (!obj2)
  					break;
  				hlist_add_head(&obj2->node,
  					       &percpu_pool->free_objs);
  				percpu_pool->obj_free++;
  				obj_pool_used++;

  				WRITE_ONCE(obj_pool_free, obj_pool_free - 1);

  			}
  		}

  		if (obj_pool_used > obj_pool_max_used)
  			obj_pool_max_used = obj_pool_used;

  		if (obj_pool_free < obj_pool_min_free)
  			obj_pool_min_free = obj_pool_free;
  	}

  	raw_spin_unlock(&pool_lock);

  init_obj:
  	if (obj) {
  		obj->object = addr;
  		obj->descr  = descr;
  		obj->state  = ODEBUG_STATE_NONE;
  		obj->astate = 0;
  		hlist_add_head(&obj->node, &b->list);
  	}

  	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);

  	WRITE_ONCE(obj_freeing, false);

  	if (!raw_spin_trylock_irqsave(&pool_lock, flags))
  		return;

  	if (obj_pool_free >= debug_objects_pool_size)
  		goto free_objs;

  	/*
  	 * 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. As it is likely that a workload
  	 * may be gearing up to use more and more objects, don't free any
  	 * of them until the next round.

  	 */
  	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);

  		WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
  		WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);

  	}

  	raw_spin_unlock_irqrestore(&pool_lock, flags);
  	return;

  free_objs:

  	/*
  	 * 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;

  		WRITE_ONCE(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 void __free_object(struct debug_obj *obj)

  {

  	struct debug_obj *objs[ODEBUG_BATCH_SIZE];
  	struct debug_percpu_free *percpu_pool;
  	int lookahead_count = 0;

  	unsigned long flags;

  	bool work;

  	local_irq_save(flags);

  	if (!obj_cache)
  		goto free_to_obj_pool;

  	/*
  	 * Try to free it into the percpu pool first.
  	 */
  	percpu_pool = this_cpu_ptr(&percpu_obj_pool);

  	if (percpu_pool->obj_free < ODEBUG_POOL_PERCPU_SIZE) {

  		hlist_add_head(&obj->node, &percpu_pool->free_objs);
  		percpu_pool->obj_free++;
  		local_irq_restore(flags);

  		return;

  	}

  	/*
  	 * As the percpu pool is full, look ahead and pull out a batch
  	 * of objects from the percpu pool and free them as well.
  	 */
  	for (; lookahead_count < ODEBUG_BATCH_SIZE; lookahead_count++) {
  		objs[lookahead_count] = __alloc_object(&percpu_pool->free_objs);
  		if (!objs[lookahead_count])
  			break;
  		percpu_pool->obj_free--;
  	}
  
  free_to_obj_pool:

  	raw_spin_lock(&pool_lock);

  	work = (obj_pool_free > debug_objects_pool_size) && obj_cache &&
  	       (obj_nr_tofree < ODEBUG_FREE_WORK_MAX);

  	obj_pool_used--;

  
  	if (work) {

  		WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);

  		hlist_add_head(&obj->node, &obj_to_free);

  		if (lookahead_count) {

  			WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + lookahead_count);

  			obj_pool_used -= lookahead_count;
  			while (lookahead_count) {
  				hlist_add_head(&objs[--lookahead_count]->node,
  					       &obj_to_free);
  			}
  		}

  
  		if ((obj_pool_free > debug_objects_pool_size) &&
  		    (obj_nr_tofree < ODEBUG_FREE_WORK_MAX)) {
  			int i;
  
  			/*
  			 * Free one more batch of objects from obj_pool.
  			 */
  			for (i = 0; i < ODEBUG_BATCH_SIZE; i++) {
  				obj = __alloc_object(&obj_pool);
  				hlist_add_head(&obj->node, &obj_to_free);

  				WRITE_ONCE(obj_pool_free, obj_pool_free - 1);
  				WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);

  			}
  		}

  	} else {

  		WRITE_ONCE(obj_pool_free, obj_pool_free + 1);

  		hlist_add_head(&obj->node, &obj_pool);

  		if (lookahead_count) {

  			WRITE_ONCE(obj_pool_free, obj_pool_free + lookahead_count);

  			obj_pool_used -= lookahead_count;
  			while (lookahead_count) {
  				hlist_add_head(&objs[--lookahead_count]->node,
  					       &obj_pool);
  			}
  		}

  	}

  	raw_spin_unlock(&pool_lock);
  	local_irq_restore(flags);

  }
  
  /*
   * Put the object back into the pool and schedule work to free objects
   * if necessary.
   */
  static void free_object(struct debug_obj *obj)
  {

  	__free_object(obj);

  	if (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {

  		WRITE_ONCE(obj_freeing, true);
  		schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);
  	}

  }
  
  /*
   * 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
  ");

  
  	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
  ",

  			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 %p is on stack %p, but NOT annotated.
  ", addr,
  			 task_stack_page(current));

  	else

  		pr_warn("object %p is NOT on stack %p, but annotated.
  ", addr,
  			 task_stack_page(current));

  	WARN_ON(1);
  }
  
  static void
  __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
  {
  	enum debug_obj_state state;

  	bool check_stack = false;

  	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;
  		}

  		check_stack = true;

  	}
  
  	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:

  		state = obj->state;

  		raw_spin_unlock_irqrestore(&db->lock, flags);

  		debug_print_object(obj, "init");

  		debug_object_fixup(descr->fixup_init, addr, state);
  		return;
  
  	case ODEBUG_STATE_DESTROYED:

  		raw_spin_unlock_irqrestore(&db->lock, flags);

  		debug_print_object(obj, "init");

  		return;

  	default:
  		break;
  	}

  	raw_spin_unlock_irqrestore(&db->lock, flags);

  	if (check_stack)
  		debug_object_is_on_stack(addr, onstack);

  }
  
  /**
   * 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) {

  		bool print_object = false;

  		switch (obj->state) {
  		case ODEBUG_STATE_INIT:
  		case ODEBUG_STATE_INACTIVE:
  			obj->state = ODEBUG_STATE_ACTIVE;

  			ret = 0;

  			break;
  
  		case ODEBUG_STATE_ACTIVE:

  			state = obj->state;

  			raw_spin_unlock_irqrestore(&db->lock, flags);

  			debug_print_object(obj, "activate");

  			ret = debug_object_fixup(descr->fixup_activate, addr, state);

  			return ret ? 0 : -EINVAL;

  
  		case ODEBUG_STATE_DESTROYED:

  			print_object = true;

  			ret = -EINVAL;

  			break;
  		default:

  			ret = 0;

  			break;
  		}

  		raw_spin_unlock_irqrestore(&db->lock, flags);

  		if (print_object)
  			debug_print_object(obj, "activate");

  		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;

  	bool print_object = false;

  
  	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

  				print_object = true;

  			break;
  
  		case ODEBUG_STATE_DESTROYED:

  			print_object = true;

  			break;
  		default:
  			break;
  		}

  	}
  
  	raw_spin_unlock_irqrestore(&db->lock, flags);
  	if (!obj) {

  		struct debug_obj o = { .object = addr,
  				       .state = ODEBUG_STATE_NOTAVAILABLE,
  				       .descr = descr };
  
  		debug_print_object(&o, "deactivate");

  	} else if (print_object) {
  		debug_print_object(obj, "deactivate");

  	}

  }

  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;

  	bool print_object = false;

  
  	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:

  		state = obj->state;

  		raw_spin_unlock_irqrestore(&db->lock, flags);

  		debug_print_object(obj, "destroy");

  		debug_object_fixup(descr->fixup_destroy, addr, state);
  		return;
  
  	case ODEBUG_STATE_DESTROYED:

  		print_object = true;

  		break;
  	default:
  		break;
  	}
  out_unlock:

  	raw_spin_unlock_irqrestore(&db->lock, flags);

  	if (print_object)
  		debug_print_object(obj, "destroy");

  }

  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:

  		state = obj->state;

  		raw_spin_unlock_irqrestore(&db->lock, flags);

  		debug_print_object(obj, "free");

  		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;

  	bool print_object = false;

  
  	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

  				print_object = true;

  			break;
  
  		default:

  			print_object = true;

  			break;
  		}

  	}
  
  	raw_spin_unlock_irqrestore(&db->lock, flags);
  	if (!obj) {

  		struct debug_obj o = { .object = addr,
  				       .state = ODEBUG_STATE_NOTAVAILABLE,
  				       .descr = descr };
  
  		debug_print_object(&o, "active_state");

  	} else if (print_object) {
  		debug_print_object(obj, "active_state");

  	}

  }

  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;

  
  	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:

  				descr = obj->descr;
  				state = obj->state;

  				raw_spin_unlock_irqrestore(&db->lock, flags);

  				debug_print_object(obj, "free");

  				debug_object_fixup(descr->fixup_free,
  						   (void *) oaddr, state);
  				goto repeat;
  			default:
  				hlist_del(&obj->node);

  				__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 (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {

  		WRITE_ONCE(obj_freeing, true);
  		schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);
  	}

  }
  
  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)
  {

  	int cpu, obj_percpu_free = 0;
  
  	for_each_possible_cpu(cpu)
  		obj_percpu_free += per_cpu(percpu_obj_pool.obj_free, cpu);

  	seq_printf(m, "max_chain     :%d
  ", debug_objects_maxchain);

  	seq_printf(m, "max_checked   :%d
  ", debug_objects_maxchecked);

  	seq_printf(m, "warnings      :%d
  ", debug_objects_warnings);
  	seq_printf(m, "fixups        :%d
  ", debug_objects_fixups);

  	seq_printf(m, "pool_free     :%d
  ", READ_ONCE(obj_pool_free) + obj_percpu_free);

  	seq_printf(m, "pool_pcp_free :%d
  ", obj_percpu_free);

  	seq_printf(m, "pool_min_free :%d
  ", obj_pool_min_free);

  	seq_printf(m, "pool_used     :%d
  ", obj_pool_used - obj_percpu_free);

  	seq_printf(m, "pool_max_used :%d
  ", obj_pool_max_used);

  	seq_printf(m, "on_free_list  :%d
  ", READ_ONCE(obj_nr_tofree));

  	seq_printf(m, "objs_allocated:%d
  ", debug_objects_allocated);
  	seq_printf(m, "objs_freed    :%d
  ", 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;

  
  	if (!debug_objects_enabled)
  		return 0;
  
  	dbgdir = debugfs_create_dir("debug_objects", NULL);

  	debugfs_create_file("stats", 0444, dbgdir, NULL, &debug_stats_fops);

  
  	return 0;

  }
  __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
  ");

  		goto out;
  	}
  	if (obj && obj->state != state) {

  		WARN(1, KERN_ERR "ODEBUG: selftest wrong state: %d != %d
  ",

  		       obj->state, state);

  		goto out;
  	}
  	if (fixups != debug_objects_fixups) {

  		WARN(1, KERN_ERR "ODEBUG: selftest fixups failed %d != %d
  ",

  		       fixups, debug_objects_fixups);

  		goto out;
  	}
  	if (warnings != debug_objects_warnings) {

  		WARN(1, KERN_ERR "ODEBUG: selftest warnings failed %d != %d
  ",

  		       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
  ");

  
  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;
  		hlist_add_head(&obj->node, &objects);
  	}
  
  	/*

  	 * debug_objects_mem_init() is now called early that only one CPU is up
  	 * and interrupts have been disabled, so it is safe to replace the
  	 * active object references.

  	 */

  
  	/* 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++;
  		}
  	}

  	pr_debug("%d of %d active objects replaced
  ",
  		 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)
  {

  	int cpu, extras;

  	if (!debug_objects_enabled)
  		return;

  	/*
  	 * Initialize the percpu object pools
  	 *
  	 * Initialization is not strictly necessary, but was done for
  	 * completeness.
  	 */
  	for_each_possible_cpu(cpu)
  		INIT_HLIST_HEAD(&per_cpu(percpu_obj_pool.free_objs, cpu));

  	obj_cache = kmem_cache_create("debug_objects_cache",
  				      sizeof (struct debug_obj), 0,

  				      SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
  				      NULL);

  	if (!obj_cache || debug_objects_replace_static_objects()) {

  		debug_objects_enabled = 0;

  		kmem_cache_destroy(obj_cache);

  		pr_warn("out of memory.
  ");

  	} else

  		debug_objects_selftest();

  
  	/*
  	 * Increase the thresholds for allocating and freeing objects
  	 * according to the number of possible CPUs available in the system.
  	 */
  	extras = num_possible_cpus() * ODEBUG_BATCH_SIZE;
  	debug_objects_pool_size += extras;
  	debug_objects_pool_min_level += extras;

  }