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6ff1cb35 AM |
1 | #include <linux/kernel.h> |
2 | #include <linux/init.h> | |
3 | #include <linux/random.h> | |
4 | #include <linux/stat.h> | |
5 | #include <linux/types.h> | |
6 | #include <linux/fs.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/fault-inject.h> | |
9 | ||
10 | /* | |
11 | * setup_fault_attr() is a helper function for various __setup handlers, so it | |
12 | * returns 0 on error, because that is what __setup handlers do. | |
13 | */ | |
14 | int __init setup_fault_attr(struct fault_attr *attr, char *str) | |
15 | { | |
16 | unsigned long probability; | |
17 | unsigned long interval; | |
18 | int times; | |
19 | int space; | |
20 | ||
21 | /* "<interval>,<probability>,<space>,<times>" */ | |
22 | if (sscanf(str, "%lu,%lu,%d,%d", | |
23 | &interval, &probability, &space, ×) < 4) { | |
24 | printk(KERN_WARNING | |
25 | "FAULT_INJECTION: failed to parse arguments\n"); | |
26 | return 0; | |
27 | } | |
28 | ||
29 | attr->probability = probability; | |
30 | attr->interval = interval; | |
31 | atomic_set(&attr->times, times); | |
32 | atomic_set(&attr->space, space); | |
33 | ||
34 | return 1; | |
35 | } | |
36 | ||
37 | static void fail_dump(struct fault_attr *attr) | |
38 | { | |
39 | if (attr->verbose > 0) | |
40 | printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n"); | |
41 | if (attr->verbose > 1) | |
42 | dump_stack(); | |
43 | } | |
44 | ||
45 | #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) | |
46 | ||
47 | /* | |
48 | * This code is stolen from failmalloc-1.0 | |
49 | * http://www.nongnu.org/failmalloc/ | |
50 | */ | |
51 | ||
52 | int should_fail(struct fault_attr *attr, ssize_t size) | |
53 | { | |
54 | if (atomic_read(&attr->times) == 0) | |
55 | return 0; | |
56 | ||
57 | if (atomic_read(&attr->space) > size) { | |
58 | atomic_sub(size, &attr->space); | |
59 | return 0; | |
60 | } | |
61 | ||
62 | if (attr->interval > 1) { | |
63 | attr->count++; | |
64 | if (attr->count % attr->interval) | |
65 | return 0; | |
66 | } | |
67 | ||
68 | if (attr->probability > random32() % 100) | |
69 | goto fail; | |
70 | ||
71 | return 0; | |
72 | ||
73 | fail: | |
74 | fail_dump(attr); | |
75 | ||
76 | if (atomic_read(&attr->times) != -1) | |
77 | atomic_dec_not_zero(&attr->times); | |
78 | ||
79 | return 1; | |
80 | } | |
81 | ||
82 | #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS | |
83 | ||
84 | static void debugfs_ul_set(void *data, u64 val) | |
85 | { | |
86 | *(unsigned long *)data = val; | |
87 | } | |
88 | ||
89 | static u64 debugfs_ul_get(void *data) | |
90 | { | |
91 | return *(unsigned long *)data; | |
92 | } | |
93 | ||
94 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); | |
95 | ||
96 | static struct dentry *debugfs_create_ul(const char *name, mode_t mode, | |
97 | struct dentry *parent, unsigned long *value) | |
98 | { | |
99 | return debugfs_create_file(name, mode, parent, value, &fops_ul); | |
100 | } | |
101 | ||
102 | static void debugfs_atomic_t_set(void *data, u64 val) | |
103 | { | |
104 | atomic_set((atomic_t *)data, val); | |
105 | } | |
106 | ||
107 | static u64 debugfs_atomic_t_get(void *data) | |
108 | { | |
109 | return atomic_read((atomic_t *)data); | |
110 | } | |
111 | ||
112 | DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, | |
113 | debugfs_atomic_t_set, "%lld\n"); | |
114 | ||
115 | static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, | |
116 | struct dentry *parent, atomic_t *value) | |
117 | { | |
118 | return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); | |
119 | } | |
120 | ||
121 | void cleanup_fault_attr_dentries(struct fault_attr *attr) | |
122 | { | |
123 | debugfs_remove(attr->dentries.probability_file); | |
124 | attr->dentries.probability_file = NULL; | |
125 | ||
126 | debugfs_remove(attr->dentries.interval_file); | |
127 | attr->dentries.interval_file = NULL; | |
128 | ||
129 | debugfs_remove(attr->dentries.times_file); | |
130 | attr->dentries.times_file = NULL; | |
131 | ||
132 | debugfs_remove(attr->dentries.space_file); | |
133 | attr->dentries.space_file = NULL; | |
134 | ||
135 | debugfs_remove(attr->dentries.verbose_file); | |
136 | attr->dentries.verbose_file = NULL; | |
137 | ||
138 | if (attr->dentries.dir) | |
139 | WARN_ON(!simple_empty(attr->dentries.dir)); | |
140 | ||
141 | debugfs_remove(attr->dentries.dir); | |
142 | attr->dentries.dir = NULL; | |
143 | } | |
144 | ||
145 | int init_fault_attr_dentries(struct fault_attr *attr, const char *name) | |
146 | { | |
147 | mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; | |
148 | struct dentry *dir; | |
149 | ||
150 | memset(&attr->dentries, 0, sizeof(attr->dentries)); | |
151 | ||
152 | dir = debugfs_create_dir(name, NULL); | |
153 | if (!dir) | |
154 | goto fail; | |
155 | attr->dentries.dir = dir; | |
156 | ||
157 | attr->dentries.probability_file = | |
158 | debugfs_create_ul("probability", mode, dir, &attr->probability); | |
159 | ||
160 | attr->dentries.interval_file = | |
161 | debugfs_create_ul("interval", mode, dir, &attr->interval); | |
162 | ||
163 | attr->dentries.times_file = | |
164 | debugfs_create_atomic_t("times", mode, dir, &attr->times); | |
165 | ||
166 | attr->dentries.space_file = | |
167 | debugfs_create_atomic_t("space", mode, dir, &attr->space); | |
168 | ||
169 | attr->dentries.verbose_file = | |
170 | debugfs_create_ul("verbose", mode, dir, &attr->verbose); | |
171 | ||
172 | if (!attr->dentries.probability_file || !attr->dentries.interval_file | |
173 | || !attr->dentries.times_file || !attr->dentries.space_file | |
174 | || !attr->dentries.verbose_file) | |
175 | goto fail; | |
176 | ||
177 | return 0; | |
178 | fail: | |
179 | cleanup_fault_attr_dentries(attr); | |
180 | return -ENOMEM; | |
181 | } | |
182 | ||
183 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |