path: root/lib/debugobjects.c

/*
 * 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
 */
#include <linux/debugobjects.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/hash.h>

#define ODEBUG_HASH_BITS	14
#define ODEBUG_HASH_SIZE	(1 << ODEBUG_HASH_BITS)

#define ODEBUG_POOL_SIZE	512
#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 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 struct kmem_cache	*obj_cache;

static int			debug_objects_maxchain __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 struct debug_obj_descr	*descr_test  __read_mostly;

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 int fill_pool(void)
{
	gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
	struct debug_obj *new;
	unsigned long flags;

	if (likely(obj_pool_free >= ODEBUG_POOL_MIN_LEVEL))
		return obj_pool_free;

	if (unlikely(!obj_cache))
		return obj_pool_free;

	while (obj_pool_free < ODEBUG_POOL_MIN_LEVEL) {

		new = kmem_cache_zalloc(obj_cache, gfp);
		if (!new)
			return obj_pool_free;

		raw_spin_lock_irqsave(&pool_lock, flags);
		hlist_add_head(&new->node, &obj_pool);
		obj_pool_free++;
		raw_spin_unlock_irqrestore(&pool_lock, flags);
	}
	return obj_pool_free;
}

/*
 * Lookup an object in the hash bucket.
 */
static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b)
{
	struct hlist_node *node;
	struct debug_obj *obj;
	int cnt = 0;

	hlist_for_each_entry(obj, node, &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;
		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.
 */
static void free_obj_work(struct work_struct *work)
{
	struct debug_obj *obj;
	unsigned long flags;

	raw_spin_lock_irqsave(&pool_lock, flags);
	while (obj_pool_free