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
 */

#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