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1 | #include <linux/kernel.h> | |
2 | #include <linux/init.h> | |
3 | #include <linux/random.h> | |
4 | #include <linux/sched.h> | |
5 | #include <linux/stat.h> | |
6 | #include <linux/types.h> | |
7 | #include <linux/fs.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/interrupt.h> | |
10 | #include <linux/stacktrace.h> | |
11 | #include <linux/fault-inject.h> | |
12 | ||
13 | /* | |
14 | * setup_fault_attr() is a helper function for various __setup handlers, so it | |
15 | * returns 0 on error, because that is what __setup handlers do. | |
16 | */ | |
17 | int __init setup_fault_attr(struct fault_attr *attr, char *str) | |
18 | { | |
19 | unsigned long probability; | |
20 | unsigned long interval; | |
21 | int times; | |
22 | int space; | |
23 | ||
24 | /* "<interval>,<probability>,<space>,<times>" */ | |
25 | if (sscanf(str, "%lu,%lu,%d,%d", | |
26 | &interval, &probability, &space, ×) < 4) { | |
27 | printk(KERN_WARNING | |
28 | "FAULT_INJECTION: failed to parse arguments\n"); | |
29 | return 0; | |
30 | } | |
31 | ||
32 | attr->probability = probability; | |
33 | attr->interval = interval; | |
34 | atomic_set(&attr->times, times); | |
35 | atomic_set(&attr->space, space); | |
36 | ||
37 | return 1; | |
38 | } | |
39 | ||
40 | static void fail_dump(struct fault_attr *attr) | |
41 | { | |
42 | if (attr->verbose > 0) | |
43 | printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n"); | |
44 | if (attr->verbose > 1) | |
45 | dump_stack(); | |
46 | } | |
47 | ||
48 | #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) | |
49 | ||
50 | static bool fail_task(struct fault_attr *attr, struct task_struct *task) | |
51 | { | |
52 | return !in_interrupt() && task->make_it_fail; | |
53 | } | |
54 | ||
55 | #define MAX_STACK_TRACE_DEPTH 32 | |
56 | ||
57 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
58 | ||
59 | static bool fail_stacktrace(struct fault_attr *attr) | |
60 | { | |
61 | struct stack_trace trace; | |
62 | int depth = attr->stacktrace_depth; | |
63 | unsigned long entries[MAX_STACK_TRACE_DEPTH]; | |
64 | int n; | |
65 | bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); | |
66 | ||
67 | if (depth == 0) | |
68 | return found; | |
69 | ||
70 | trace.nr_entries = 0; | |
71 | trace.entries = entries; | |
72 | trace.max_entries = depth; | |
73 | trace.skip = 1; | |
74 | ||
75 | save_stack_trace(&trace); | |
76 | for (n = 0; n < trace.nr_entries; n++) { | |
77 | if (attr->reject_start <= entries[n] && | |
78 | entries[n] < attr->reject_end) | |
79 | return false; | |
80 | if (attr->require_start <= entries[n] && | |
81 | entries[n] < attr->require_end) | |
82 | found = true; | |
83 | } | |
84 | return found; | |
85 | } | |
86 | ||
87 | #else | |
88 | ||
89 | static inline bool fail_stacktrace(struct fault_attr *attr) | |
90 | { | |
91 | return true; | |
92 | } | |
93 | ||
94 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
95 | ||
96 | /* | |
97 | * This code is stolen from failmalloc-1.0 | |
98 | * http://www.nongnu.org/failmalloc/ | |
99 | */ | |
100 | ||
101 | bool should_fail(struct fault_attr *attr, ssize_t size) | |
102 | { | |
103 | if (attr->task_filter && !fail_task(attr, current)) | |
104 | return false; | |
105 | ||
106 | if (atomic_read(&attr->times) == 0) | |
107 | return false; | |
108 | ||
109 | if (atomic_read(&attr->space) > size) { | |
110 | atomic_sub(size, &attr->space); | |
111 | return false; | |
112 | } | |
113 | ||
114 | if (attr->interval > 1) { | |
115 | attr->count++; | |
116 | if (attr->count % attr->interval) | |
117 | return false; | |
118 | } | |
119 | ||
120 | if (attr->probability <= random32() % 100) | |
121 | return false; | |
122 | ||
123 | if (!fail_stacktrace(attr)) | |
124 | return false; | |
125 | ||
126 | fail_dump(attr); | |
127 | ||
128 | if (atomic_read(&attr->times) != -1) | |
129 | atomic_dec_not_zero(&attr->times); | |
130 | ||
131 | return true; | |
132 | } | |
133 | ||
134 | #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS | |
135 | ||
136 | static int debugfs_ul_set(void *data, u64 val) | |
137 | { | |
138 | *(unsigned long *)data = val; | |
139 | return 0; | |
140 | } | |
141 | ||
142 | static int debugfs_ul_get(void *data, u64 *val) | |
143 | { | |
144 | *val = *(unsigned long *)data; | |
145 | return 0; | |
146 | } | |
147 | ||
148 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); | |
149 | ||
150 | static struct dentry *debugfs_create_ul(const char *name, mode_t mode, | |
151 | struct dentry *parent, unsigned long *value) | |
152 | { | |
153 | return debugfs_create_file(name, mode, parent, value, &fops_ul); | |
154 | } | |
155 | ||
156 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
157 | ||
158 | static int debugfs_stacktrace_depth_set(void *data, u64 val) | |
159 | { | |
160 | *(unsigned long *)data = | |
161 | min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); | |
162 | ||
163 | return 0; | |
164 | } | |
165 | ||
166 | DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, | |
167 | debugfs_stacktrace_depth_set, "%llu\n"); | |
168 | ||
169 | static struct dentry *debugfs_create_stacktrace_depth( | |
170 | const char *name, mode_t mode, | |
171 | struct dentry *parent, unsigned long *value) | |
172 | { | |
173 | return debugfs_create_file(name, mode, parent, value, | |
174 | &fops_stacktrace_depth); | |
175 | } | |
176 | ||
177 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
178 | ||
179 | static int debugfs_atomic_t_set(void *data, u64 val) | |
180 | { | |
181 | atomic_set((atomic_t *)data, val); | |
182 | return 0; | |
183 | } | |
184 | ||
185 | static int debugfs_atomic_t_get(void *data, u64 *val) | |
186 | { | |
187 | *val = atomic_read((atomic_t *)data); | |
188 | return 0; | |
189 | } | |
190 | ||
191 | DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, | |
192 | debugfs_atomic_t_set, "%lld\n"); | |
193 | ||
194 | static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, | |
195 | struct dentry *parent, atomic_t *value) | |
196 | { | |
197 | return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); | |
198 | } | |
199 | ||
200 | struct dentry *fault_create_debugfs_attr(const char *name, | |
201 | struct dentry *parent, struct fault_attr *attr) | |
202 | { | |
203 | mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; | |
204 | struct dentry *dir; | |
205 | ||
206 | dir = debugfs_create_dir(name, parent); | |
207 | if (!dir) | |
208 | return ERR_PTR(-ENOMEM); | |
209 | ||
210 | if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) | |
211 | goto fail; | |
212 | if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) | |
213 | goto fail; | |
214 | if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) | |
215 | goto fail; | |
216 | if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) | |
217 | goto fail; | |
218 | if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) | |
219 | goto fail; | |
220 | if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) | |
221 | goto fail; | |
222 | ||
223 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
224 | ||
225 | if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, | |
226 | &attr->stacktrace_depth)) | |
227 | goto fail; | |
228 | if (!debugfs_create_ul("require-start", mode, dir, | |
229 | &attr->require_start)) | |
230 | goto fail; | |
231 | if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) | |
232 | goto fail; | |
233 | if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) | |
234 | goto fail; | |
235 | if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) | |
236 | goto fail; | |
237 | ||
238 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
239 | ||
240 | return dir; | |
241 | fail: | |
242 | debugfs_remove_recursive(dir); | |
243 | ||
244 | return ERR_PTR(-ENOMEM); | |
245 | } | |
246 | ||
247 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |