summaryrefslogtreecommitdiff
path: root/lib/ref_tracker.c
blob: a6789c0c626b0f68ad67c264cd19177a63fb82d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
// 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;
	gfp_t gfp_mask = gfp;
	unsigned long flags;

	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);
	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);