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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 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 | EXPORT_SYMBOL_GPL(setup_fault_attr); | |
40 | ||
41 | static void fail_dump(struct fault_attr *attr) | |
42 | { | |
43 | if (attr->verbose > 0) | |
44 | printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n"); | |
45 | if (attr->verbose > 1) | |
46 | dump_stack(); | |
47 | } | |
48 | ||
49 | #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) | |
50 | ||
51 | static bool fail_task(struct fault_attr *attr, struct task_struct *task) | |
52 | { | |
53 | return !in_interrupt() && task->make_it_fail; | |
54 | } | |
55 | ||
56 | #define MAX_STACK_TRACE_DEPTH 32 | |
57 | ||
58 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
59 | ||
60 | static bool fail_stacktrace(struct fault_attr *attr) | |
61 | { | |
62 | struct stack_trace trace; | |
63 | int depth = attr->stacktrace_depth; | |
64 | unsigned long entries[MAX_STACK_TRACE_DEPTH]; | |
65 | int n; | |
66 | bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); | |
67 | ||
68 | if (depth == 0) | |
69 | return found; | |
70 | ||
71 | trace.nr_entries = 0; | |
72 | trace.entries = entries; | |
73 | trace.max_entries = depth; | |
74 | trace.skip = 1; | |
75 | ||
76 | save_stack_trace(&trace); | |
77 | for (n = 0; n < trace.nr_entries; n++) { | |
78 | if (attr->reject_start <= entries[n] && | |
79 | entries[n] < attr->reject_end) | |
80 | return false; | |
81 | if (attr->require_start <= entries[n] && | |
82 | entries[n] < attr->require_end) | |
83 | found = true; | |
84 | } | |
85 | return found; | |
86 | } | |
87 | ||
88 | #else | |
89 | ||
90 | static inline bool fail_stacktrace(struct fault_attr *attr) | |
91 | { | |
92 | return true; | |
93 | } | |
94 | ||
95 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
96 | ||
97 | /* | |
98 | * This code is stolen from failmalloc-1.0 | |
99 | * http://www.nongnu.org/failmalloc/ | |
100 | */ | |
101 | ||
102 | bool should_fail(struct fault_attr *attr, ssize_t size) | |
103 | { | |
104 | if (attr->task_filter && !fail_task(attr, current)) | |
105 | return false; | |
106 | ||
107 | if (atomic_read(&attr->times) == 0) | |
108 | return false; | |
109 | ||
110 | if (atomic_read(&attr->space) > size) { | |
111 | atomic_sub(size, &attr->space); | |
112 | return false; | |
113 | } | |
114 | ||
115 | if (attr->interval > 1) { | |
116 | attr->count++; | |
117 | if (attr->count % attr->interval) | |
118 | return false; | |
119 | } | |
120 | ||
121 | if (attr->probability <= random32() % 100) | |
122 | return false; | |
123 | ||
124 | if (!fail_stacktrace(attr)) | |
125 | return false; | |
126 | ||
127 | fail_dump(attr); | |
128 | ||
129 | if (atomic_read(&attr->times) != -1) | |
130 | atomic_dec_not_zero(&attr->times); | |
131 | ||
132 | return true; | |
133 | } | |
134 | EXPORT_SYMBOL_GPL(should_fail); | |
135 | ||
136 | #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS | |
137 | ||
138 | static int debugfs_ul_set(void *data, u64 val) | |
139 | { | |
140 | *(unsigned long *)data = val; | |
141 | return 0; | |
142 | } | |
143 | ||
144 | static int debugfs_ul_get(void *data, u64 *val) | |
145 | { | |
146 | *val = *(unsigned long *)data; | |
147 | return 0; | |
148 | } | |
149 | ||
150 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); | |
151 | ||
152 | static struct dentry *debugfs_create_ul(const char *name, umode_t mode, | |
153 | struct dentry *parent, unsigned long *value) | |
154 | { | |
155 | return debugfs_create_file(name, mode, parent, value, &fops_ul); | |
156 | } | |
157 | ||
158 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
159 | ||
160 | static int debugfs_stacktrace_depth_set(void *data, u64 val) | |
161 | { | |
162 | *(unsigned long *)data = | |
163 | min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); | |
164 | ||
165 | return 0; | |
166 | } | |
167 | ||
168 | DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, | |
169 | debugfs_stacktrace_depth_set, "%llu\n"); | |
170 | ||
171 | static struct dentry *debugfs_create_stacktrace_depth( | |
172 | const char *name, umode_t mode, | |
173 | struct dentry *parent, unsigned long *value) | |
174 | { | |
175 | return debugfs_create_file(name, mode, parent, value, | |
176 | &fops_stacktrace_depth); | |
177 | } | |
178 | ||
179 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
180 | ||
181 | static int debugfs_atomic_t_set(void *data, u64 val) | |
182 | { | |
183 | atomic_set((atomic_t *)data, val); | |
184 | return 0; | |
185 | } | |
186 | ||
187 | static int debugfs_atomic_t_get(void *data, u64 *val) | |
188 | { | |
189 | *val = atomic_read((atomic_t *)data); | |
190 | return 0; | |
191 | } | |
192 | ||
193 | DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, | |
194 | debugfs_atomic_t_set, "%lld\n"); | |
195 | ||
196 | static struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode, | |
197 | struct dentry *parent, atomic_t *value) | |
198 | { | |
199 | return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); | |
200 | } | |
201 | ||
202 | struct dentry *fault_create_debugfs_attr(const char *name, | |
203 | struct dentry *parent, struct fault_attr *attr) | |
204 | { | |
205 | umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; | |
206 | struct dentry *dir; | |
207 | ||
208 | dir = debugfs_create_dir(name, parent); | |
209 | if (!dir) | |
210 | return ERR_PTR(-ENOMEM); | |
211 | ||
212 | if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) | |
213 | goto fail; | |
214 | if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) | |
215 | goto fail; | |
216 | if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) | |
217 | goto fail; | |
218 | if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) | |
219 | goto fail; | |
220 | if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) | |
221 | goto fail; | |
222 | if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) | |
223 | goto fail; | |
224 | ||
225 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
226 | ||
227 | if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, | |
228 | &attr->stacktrace_depth)) | |
229 | goto fail; | |
230 | if (!debugfs_create_ul("require-start", mode, dir, | |
231 | &attr->require_start)) | |
232 | goto fail; | |
233 | if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) | |
234 | goto fail; | |
235 | if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) | |
236 | goto fail; | |
237 | if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) | |
238 | goto fail; | |
239 | ||
240 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
241 | ||
242 | return dir; | |
243 | fail: | |
244 | debugfs_remove_recursive(dir); | |
245 | ||
246 | return ERR_PTR(-ENOMEM); | |
247 | } | |
248 | EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); | |
249 | ||
250 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |