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review.shift-gmbh.com / SHIFTPHONES / mainline / linux / fb75a3791a8032848c987db29b622878d8fe2b1c / . / lib / ref_tracker.c
blob: 0ae2e66dcf0fdb976f4cb99e747c9448b37f22cc [file] [log] [blame]
Eric Dumazet4e669342021-12-04 20:21:55 -0800[diff] [blame]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
10struct 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
17void 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}
41EXPORT_SYMBOL(ref_tracker_dir_exit);
42
43void 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}
63EXPORT_SYMBOL(ref_tracker_dir_print);
64
65int 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}
89EXPORT_SYMBOL_GPL(ref_tracker_alloc);
90
91int 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}
140EXPORT_SYMBOL_GPL(ref_tracker_free);