[linux-2.6-block.git] / lib / ref_tracker.c

// SPDX-License-Identifier: GPL-2.0-or-later

#define pr_fmt(fmt) "ref_tracker: " fmt

#include <linux/export.h>
#include <linux/list_sort.h>
#include <linux/ref_tracker.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/stackdepot.h>

#define REF_TRACKER_STACK_ENTRIES 16
#define STACK_BUF_SIZE 1024

struct ref_tracker {
	struct list_head	head;   /* anchor into dir->list or dir->quarantine */
	bool			dead;
	depot_stack_handle_t	alloc_stack_handle;
	depot_stack_handle_t	free_stack_handle;
};

struct ref_tracker_dir_stats {
	int total;
	int count;
	struct {
		depot_stack_handle_t stack_handle;
		unsigned int count;
	} stacks[];
};

static struct ref_tracker_dir_stats *
ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
{
	struct ref_tracker_dir_stats *stats;
	struct ref_tracker *tracker;

	stats = kmalloc(struct_size(stats, stacks, limit),
			GFP_NOWAIT | __GFP_NOWARN);
	if (!stats)
		return ERR_PTR(-ENOMEM);
	stats->total = 0;
	stats->count = 0;

	list_for_each_entry(tracker, &dir->list, head) {
		depot_stack_handle_t stack = tracker->alloc_stack_handle;
		int i;

		++stats->total;
		for (i = 0; i < stats->count; ++i)
			if (stats->stacks[i].stack_handle == stack)
				break;
		if (i >= limit)
			continue;
		if (i >= stats->count) {
			stats->stacks[i].stack_handle = stack;
			stats->stacks[i].count = 0;
			++stats->count;
		}
		++stats->stacks[i].count;
	}

	return stats;
}

void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
				  unsigned int display_limit)
{
	struct ref_tracker_dir_stats *stats;
	unsigned int i = 0, skipped;
	depot_stack_handle_t stack;
	char *sbuf;

	lockdep_assert_held(&dir->lock);

	if (list_empty(&dir->list))
		return;

	stats = ref_tracker_get_stats(dir, display_limit);
	if (IS_ERR(stats)) {
		pr_err("%s@%pK: couldn't get stats, error %pe\n",
		       dir->name, dir, stats);
		return;
	}

	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);

	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
		stack = stats->stacks[i].stack_handle;
		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
			sbuf[0] = 0;
		pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
		       stats->stacks[i].count, stats->total, sbuf);
		skipped -= stats->stacks[i].count;
	}

	if (skipped)
		pr_err("%s@%pK skipped reports about %d/%d users.\n",
		       dir->name, dir, skipped, stats->total);

	kfree(sbuf);

	kfree(stats);
}
EXPORT_SYMBOL(ref_tracker_dir_print_locked);

void ref_tracker_dir_print(struct ref_tracker_dir *dir,
			   unsigned int display_limit)
{
	unsigned long flags;

	spin_lock_irqsave(&dir->lock, flags);
	ref_tracker_dir_print_locked(dir, display_limit);
	spin_unlock_irqrestore(&dir->lock, flags);
}
EXPORT_SYMBOL(ref_tracker_dir_print);

void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
{
	struct ref_tracker *tracker, *n;
	unsigned long flags;
	bool leak = false;

	dir->dead = true;
	spin_lock_irqsave(&dir->lock, flags);
	list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
		list_del(&tracker->head);
		kfree(tracker);
		dir->quarantine_avail++;
	}
	if (!list_empty(&dir->list)) {
		ref_tracker_dir_print_locked(dir, 16);
		leak = true;
		list_for_each_entry_safe(tracker, n, &dir->list, head) {
			list_del(&tracker->head);
			kfree(tracker);
		}
	}
	spin_unlock_irqrestore(&dir->lock, flags);
	WARN_ON_ONCE(leak);
	WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
	WARN_ON_ONCE(refcount_read(&dir->no_tracker) != 1);
}
EXPORT_SYMBOL(ref_tracker_dir_exit);

int ref_tracker_alloc(struct ref_tracker_dir *dir,
		      struct ref_tracker **trackerp,
		      gfp_t gfp)
{
	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
	struct ref_tracker *tracker;
	unsigned int nr_entries;
	gfp_t gfp_mask = gfp;
	unsigned long flags;

	WARN_ON_ONCE(dir->dead);

	if (!trackerp) {
		refcount_inc(&dir->no_tracker);
		return 0;
	}
	if (gfp & __GFP_DIRECT_RECLAIM)
		gfp_mask |= __GFP_NOFAIL;
	*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
	if (unlikely(!tracker)) {
		pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
		refcount_inc(&dir->untracked);
		return -ENOMEM;
	}
	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
	tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp);

	spin_lock_irqsave(&dir->lock, flags);
	list_add(&tracker->head, &dir->list);
	spin_unlock_irqrestore(&dir->lock, flags);
	return 0;
}
EXPORT_SYMBOL_GPL(ref_tracker_alloc);

int ref_tracker_free(struct ref_tracker_dir *dir,
		     struct ref_tracker **trackerp)
{
	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
	depot_stack_handle_t stack_handle;
	struct ref_tracker *tracker;
	unsigned int nr_entries;
	unsigned long flags;

	WARN_ON_ONCE(dir->dead);

	if (!trackerp) {
		refcount_dec(&dir->no_tracker);
		return 0;
	}
	tracker = *trackerp;
	if (!tracker) {
		refcount_dec(&dir->untracked);
		return -EEXIST;
	}
	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
	stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);

	spin_lock_irqsave(&dir->lock, flags);
	if (tracker->dead) {
		pr_err("reference already released.\n");
		if (tracker->alloc_stack_handle) {
			pr_err("allocated in:\n");
			stack_depot_print(tracker->alloc_stack_handle);
		}
		if (tracker->free_stack_handle) {
			pr_err("freed in:\n");
			stack_depot_print(tracker->free_stack_handle);
		}
		spin_unlock_irqrestore(&dir->lock, flags);
		WARN_ON_ONCE(1);
		return -EINVAL;
	}
	tracker->dead = true;

	tracker->free_stack_handle = stack_handle;

	list_move_tail(&tracker->head, &dir->quarantine);
	if (!dir->quarantine_avail) {
		tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head);
		list_del(&tracker->head);
	} else {
		dir->quarantine_avail--;
		tracker = NULL;
	}
	spin_unlock_irqrestore(&dir->lock, flags);

	kfree(tracker);
	return 0;
}
EXPORT_SYMBOL_GPL(ref_tracker_free);
Commit	Line	Data
4e66934e	1	// SPDX-License-Identifier: GPL-2.0-or-later
b6d7c0eb AH	2
	3	#define pr_fmt(fmt) "ref_tracker: " fmt
	4
4e66934e	5	#include <linux/export.h>
b6d7c0eb	6	#include <linux/list_sort.h>
4e66934e ED	7	#include <linux/ref_tracker.h>
	8	#include <linux/slab.h>
	9	#include <linux/stacktrace.h>
	10	#include <linux/stackdepot.h>
	11
	12	#define REF_TRACKER_STACK_ENTRIES 16
b6d7c0eb	13	#define STACK_BUF_SIZE 1024
4e66934e ED	14
	15	struct ref_tracker {
	16	struct list_head head; /* anchor into dir->list or dir->quarantine */
	17	bool dead;
	18	depot_stack_handle_t alloc_stack_handle;
	19	depot_stack_handle_t free_stack_handle;
	20	};
	21
b6d7c0eb AH	22	struct ref_tracker_dir_stats {
	23	int total;
	24	int count;
	25	struct {
	26	depot_stack_handle_t stack_handle;
	27	unsigned int count;
	28	} stacks[];
	29	};
	30
	31	static struct ref_tracker_dir_stats *
	32	ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
7a113ff6	33	{
b6d7c0eb	34	struct ref_tracker_dir_stats *stats;
7a113ff6	35	struct ref_tracker *tracker;
7a113ff6	36
b6d7c0eb AH	37	stats = kmalloc(struct_size(stats, stacks, limit),
	38	GFP_NOWAIT \| __GFP_NOWARN);
	39	if (!stats)
	40	return ERR_PTR(-ENOMEM);
	41	stats->total = 0;
	42	stats->count = 0;
7a113ff6 AH	43
7a113ff6 AH	44	list_for_each_entry(tracker, &dir->list, head) {
b6d7c0eb AH	45	depot_stack_handle_t stack = tracker->alloc_stack_handle;
	46	int i;
	47
	48	++stats->total;
	49	for (i = 0; i < stats->count; ++i)
	50	if (stats->stacks[i].stack_handle == stack)
	51	break;
	52	if (i >= limit)
	53	continue;
	54	if (i >= stats->count) {
	55	stats->stacks[i].stack_handle = stack;
	56	stats->stacks[i].count = 0;
	57	++stats->count;
7a113ff6	58	}
b6d7c0eb	59	++stats->stacks[i].count;
7a113ff6	60	}
b6d7c0eb AH	61
	62	return stats;
	63	}
	64
	65	void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
	66	unsigned int display_limit)
	67	{
	68	struct ref_tracker_dir_stats *stats;
	69	unsigned int i = 0, skipped;
	70	depot_stack_handle_t stack;
	71	char *sbuf;
	72
	73	lockdep_assert_held(&dir->lock);
	74
	75	if (list_empty(&dir->list))
	76	return;
	77
	78	stats = ref_tracker_get_stats(dir, display_limit);
	79	if (IS_ERR(stats)) {
	80	pr_err("%s@%pK: couldn't get stats, error %pe\n",
	81	dir->name, dir, stats);
	82	return;
	83	}
	84
	85	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT \| __GFP_NOWARN);
	86
	87	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
	88	stack = stats->stacks[i].stack_handle;
	89	if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
	90	sbuf[0] = 0;
	91	pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
	92	stats->stacks[i].count, stats->total, sbuf);
	93	skipped -= stats->stacks[i].count;
	94	}
	95
	96	if (skipped)
	97	pr_err("%s@%pK skipped reports about %d/%d users.\n",
	98	dir->name, dir, skipped, stats->total);
	99
	100	kfree(sbuf);
	101
	102	kfree(stats);
7a113ff6 AH	103	}
	104	EXPORT_SYMBOL(ref_tracker_dir_print_locked);
	105
	106	void ref_tracker_dir_print(struct ref_tracker_dir *dir,
	107	unsigned int display_limit)
	108	{
	109	unsigned long flags;
	110
	111	spin_lock_irqsave(&dir->lock, flags);
	112	ref_tracker_dir_print_locked(dir, display_limit);
	113	spin_unlock_irqrestore(&dir->lock, flags);
	114	}
	115	EXPORT_SYMBOL(ref_tracker_dir_print);
	116
4e66934e ED	117	void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
	118	{
	119	struct ref_tracker tracker, n;
	120	unsigned long flags;
	121	bool leak = false;
	122
e3ececfe	123	dir->dead = true;
4e66934e ED	124	spin_lock_irqsave(&dir->lock, flags);
	125	list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
	126	list_del(&tracker->head);
	127	kfree(tracker);
	128	dir->quarantine_avail++;
	129	}
7a113ff6 AH	130	if (!list_empty(&dir->list)) {
7a113ff6 AH	131	ref_tracker_dir_print_locked(dir, 16);
4e66934e	132	leak = true;
7a113ff6 AH	133	list_for_each_entry_safe(tracker, n, &dir->list, head) {
	134	list_del(&tracker->head);
	135	kfree(tracker);
	136	}
4e66934e ED	137	}
	138	spin_unlock_irqrestore(&dir->lock, flags);
	139	WARN_ON_ONCE(leak);
	140	WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
8fd5522f	141	WARN_ON_ONCE(refcount_read(&dir->no_tracker) != 1);
4e66934e ED	142	}
	143	EXPORT_SYMBOL(ref_tracker_dir_exit);
	144
4e66934e ED	145	int ref_tracker_alloc(struct ref_tracker_dir *dir,
	146	struct ref_tracker **trackerp,
	147	gfp_t gfp)
	148	{
	149	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
	150	struct ref_tracker *tracker;
	151	unsigned int nr_entries;
c12837d1	152	gfp_t gfp_mask = gfp;
4e66934e ED	153	unsigned long flags;
4e66934e ED	154
e3ececfe ED	155	WARN_ON_ONCE(dir->dead);
e3ececfe ED	156
8fd5522f ED	157	if (!trackerp) {
	158	refcount_inc(&dir->no_tracker);
	159	return 0;
	160	}
c12837d1 ED	161	if (gfp & __GFP_DIRECT_RECLAIM)
	162	gfp_mask \|= __GFP_NOFAIL;
	163	trackerp = tracker = kzalloc(sizeof(tracker), gfp_mask);
4e66934e ED	164	if (unlikely(!tracker)) {
	165	pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
	166	refcount_inc(&dir->untracked);
	167	return -ENOMEM;
	168	}
	169	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
4e66934e ED	170	tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp);
	171
	172	spin_lock_irqsave(&dir->lock, flags);
	173	list_add(&tracker->head, &dir->list);
	174	spin_unlock_irqrestore(&dir->lock, flags);
	175	return 0;
	176	}
	177	EXPORT_SYMBOL_GPL(ref_tracker_alloc);
	178
	179	int ref_tracker_free(struct ref_tracker_dir *dir,
	180	struct ref_tracker **trackerp)
	181	{
	182	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
4e66934e	183	depot_stack_handle_t stack_handle;
8fd5522f	184	struct ref_tracker *tracker;
4e66934e ED	185	unsigned int nr_entries;
	186	unsigned long flags;
	187
e3ececfe ED	188	WARN_ON_ONCE(dir->dead);
e3ececfe ED	189
8fd5522f ED	190	if (!trackerp) {
	191	refcount_dec(&dir->no_tracker);
	192	return 0;
	193	}
	194	tracker = *trackerp;
4e66934e ED	195	if (!tracker) {
	196	refcount_dec(&dir->untracked);
	197	return -EEXIST;
	198	}
	199	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
4e66934e ED	200	stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
	201
	202	spin_lock_irqsave(&dir->lock, flags);
	203	if (tracker->dead) {
	204	pr_err("reference already released.\n");
	205	if (tracker->alloc_stack_handle) {
	206	pr_err("allocated in:\n");
	207	stack_depot_print(tracker->alloc_stack_handle);
	208	}
	209	if (tracker->free_stack_handle) {
	210	pr_err("freed in:\n");
	211	stack_depot_print(tracker->free_stack_handle);
	212	}
	213	spin_unlock_irqrestore(&dir->lock, flags);
	214	WARN_ON_ONCE(1);
	215	return -EINVAL;
	216	}
	217	tracker->dead = true;
	218
	219	tracker->free_stack_handle = stack_handle;
	220
	221	list_move_tail(&tracker->head, &dir->quarantine);
	222	if (!dir->quarantine_avail) {
	223	tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head);
	224	list_del(&tracker->head);
	225	} else {
	226	dir->quarantine_avail--;
	227	tracker = NULL;
	228	}
	229	spin_unlock_irqrestore(&dir->lock, flags);
	230
	231	kfree(tracker);
	232	return 0;
	233	}
	234	EXPORT_SYMBOL_GPL(ref_tracker_free);