[linux.git] / lib / ref_tracker.c

// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/export.h>
#include <linux/ref_tracker.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/stackdepot.h>

#define REF_TRACKER_STACK_ENTRIES 16

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;
};

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

	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++;
	}
	list_for_each_entry_safe(tracker, n, &dir->list, head) {
		pr_err("leaked reference.\n");
		if (tracker->alloc_stack_handle)
			stack_depot_print(tracker->alloc_stack_handle);
		leak = true;
		list_del(&tracker->head);
		kfree(tracker);
	}
	spin_unlock_irqrestore(&dir->lock, flags);
	WARN_ON_ONCE(leak);
	WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
}
EXPORT_SYMBOL(ref_tracker_dir_exit);

void ref_tracker_dir_print(struct ref_tracker_dir *dir,
			   unsigned int display_limit)
{
	struct ref_tracker *tracker;
	unsigned long flags;
	unsigned int i = 0;

	spin_lock_irqsave(&dir->lock, flags);
	list_for_each_entry(tracker, &dir->list, head) {
		if (i < display_limit) {
			pr_err("leaked reference.\n");
			if (tracker->alloc_stack_handle)
				stack_depot_print(tracker->alloc_stack_handle);
			i++;
		} else {
			break;
		}
	}
	spin_unlock_irqrestore(&dir->lock, flags);
}
EXPORT_SYMBOL(ref_tracker_dir_print);

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;
	unsigned long flags;

	*trackerp = tracker = kzalloc(sizeof(*tracker), gfp | __GFP_NOFAIL);
	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);
	nr_entries = filter_irq_stacks(entries, nr_entries);
	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];
	struct ref_tracker *tracker = *trackerp;
	depot_stack_handle_t stack_handle;
	unsigned int nr_entries;
	unsigned long flags;

	if (!tracker) {
		refcount_dec(&dir->untracked);
		return -EEXIST;
	}
	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
	nr_entries = filter_irq_stacks(entries, nr_entries);
	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 ED	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	#include <linux/export.h>
	3	#include <linux/ref_tracker.h>
	4	#include <linux/slab.h>
	5	#include <linux/stacktrace.h>
	6	#include <linux/stackdepot.h>
	7
	8	#define REF_TRACKER_STACK_ENTRIES 16
	9
	10	struct ref_tracker {
	11	struct list_head head; /* anchor into dir->list or dir->quarantine */
	12	bool dead;
	13	depot_stack_handle_t alloc_stack_handle;
	14	depot_stack_handle_t free_stack_handle;
	15	};
	16
	17	void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
	18	{
	19	struct ref_tracker tracker, n;
	20	unsigned long flags;
	21	bool leak = false;
	22
	23	spin_lock_irqsave(&dir->lock, flags);
	24	list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
	25	list_del(&tracker->head);
	26	kfree(tracker);
	27	dir->quarantine_avail++;
	28	}
	29	list_for_each_entry_safe(tracker, n, &dir->list, head) {
	30	pr_err("leaked reference.\n");
	31	if (tracker->alloc_stack_handle)
	32	stack_depot_print(tracker->alloc_stack_handle);
	33	leak = true;
	34	list_del(&tracker->head);
	35	kfree(tracker);
	36	}
	37	spin_unlock_irqrestore(&dir->lock, flags);
	38	WARN_ON_ONCE(leak);
	39	WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);
	40	}
	41	EXPORT_SYMBOL(ref_tracker_dir_exit);
	42
	43	void ref_tracker_dir_print(struct ref_tracker_dir *dir,
	44	unsigned int display_limit)
	45	{
	46	struct ref_tracker *tracker;
	47	unsigned long flags;
	48	unsigned int i = 0;
	49
	50	spin_lock_irqsave(&dir->lock, flags);
	51	list_for_each_entry(tracker, &dir->list, head) {
	52	if (i < display_limit) {
	53	pr_err("leaked reference.\n");
	54	if (tracker->alloc_stack_handle)
	55	stack_depot_print(tracker->alloc_stack_handle);
	56	i++;
	57	} else {
	58	break;
	59	}
	60	}
	61	spin_unlock_irqrestore(&dir->lock, flags);
	62	}
	63	EXPORT_SYMBOL(ref_tracker_dir_print);
	64
65	int ref_tracker_alloc(struct ref_tracker_dir *dir,
66	struct ref_tracker **trackerp,
67	gfp_t gfp)
68	{
69	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
70	struct ref_tracker *tracker;
71	unsigned int nr_entries;
72	unsigned long flags;
73
74	trackerp = tracker = kzalloc(sizeof(tracker), gfp \| __GFP_NOFAIL);
75	if (unlikely(!tracker)) {
76	pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
77	refcount_inc(&dir->untracked);
78	return -ENOMEM;
79	}
80	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
81	nr_entries = filter_irq_stacks(entries, nr_entries);
82	tracker->alloc_stack_handle = stack_depot_save(entries, nr_entries, gfp);
83
84	spin_lock_irqsave(&dir->lock, flags);
85	list_add(&tracker->head, &dir->list);
86	spin_unlock_irqrestore(&dir->lock, flags);
87	return 0;
88	}
89	EXPORT_SYMBOL_GPL(ref_tracker_alloc);
90
91	int ref_tracker_free(struct ref_tracker_dir *dir,
92	struct ref_tracker **trackerp)
93	{
94	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
95	struct ref_tracker tracker = trackerp;
96	depot_stack_handle_t stack_handle;
97	unsigned int nr_entries;
98	unsigned long flags;
99
100	if (!tracker) {
101	refcount_dec(&dir->untracked);
102	return -EEXIST;
103	}
104	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
105	nr_entries = filter_irq_stacks(entries, nr_entries);
106	stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
107
108	spin_lock_irqsave(&dir->lock, flags);
109	if (tracker->dead) {
110	pr_err("reference already released.\n");
111	if (tracker->alloc_stack_handle) {
112	pr_err("allocated in:\n");
113	stack_depot_print(tracker->alloc_stack_handle);
114	}
115	if (tracker->free_stack_handle) {
116	pr_err("freed in:\n");
117	stack_depot_print(tracker->free_stack_handle);
118	}
119	spin_unlock_irqrestore(&dir->lock, flags);
120	WARN_ON_ONCE(1);
121	return -EINVAL;
122	}
123	tracker->dead = true;
124
125	tracker->free_stack_handle = stack_handle;
126
127	list_move_tail(&tracker->head, &dir->quarantine);
128	if (!dir->quarantine_avail) {
129	tracker = list_first_entry(&dir->quarantine, struct ref_tracker, head);
130	list_del(&tracker->head);
131	} else {
132	dir->quarantine_avail--;
133	tracker = NULL;
134	}
135	spin_unlock_irqrestore(&dir->lock, flags);
136
137	kfree(tracker);
138	return 0;
139	}
140	EXPORT_SYMBOL_GPL(ref_tracker_free);