fault_inject: silence a warning
[linux-2.6.git] / lib / fault-inject.c
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/interrupt.h>
9 #include <linux/unwind.h>
10 #include <linux/stacktrace.h>
11 #include <linux/kallsyms.h>
12 #include <linux/fault-inject.h>
13
14 /*
15  * setup_fault_attr() is a helper function for various __setup handlers, so it
16  * returns 0 on error, because that is what __setup handlers do.
17  */
18 int __init setup_fault_attr(struct fault_attr *attr, char *str)
19 {
20         unsigned long probability;
21         unsigned long interval;
22         int times;
23         int space;
24
25         /* "<interval>,<probability>,<space>,<times>" */
26         if (sscanf(str, "%lu,%lu,%d,%d",
27                         &interval, &probability, &space, &times) < 4) {
28                 printk(KERN_WARNING
29                         "FAULT_INJECTION: failed to parse arguments\n");
30                 return 0;
31         }
32
33         attr->probability = probability;
34         attr->interval = interval;
35         atomic_set(&attr->times, times);
36         atomic_set(&attr->space, space);
37
38         return 1;
39 }
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
135 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
136
137 static void debugfs_ul_set(void *data, u64 val)
138 {
139         *(unsigned long *)data = val;
140 }
141
142 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
143 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
144 {
145         *(unsigned long *)data =
146                 val < MAX_STACK_TRACE_DEPTH ?
147                 val : MAX_STACK_TRACE_DEPTH;
148 }
149 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
150
151 static u64 debugfs_ul_get(void *data)
152 {
153         return *(unsigned long *)data;
154 }
155
156 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
157
158 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
159                                 struct dentry *parent, unsigned long *value)
160 {
161         return debugfs_create_file(name, mode, parent, value, &fops_ul);
162 }
163
164 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
165 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
166                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
167
168 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
169         const char *name, mode_t mode,
170         struct dentry *parent, unsigned long *value)
171 {
172         return debugfs_create_file(name, mode, parent, value,
173                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
174 }
175 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
176
177 static void debugfs_atomic_t_set(void *data, u64 val)
178 {
179         atomic_set((atomic_t *)data, val);
180 }
181
182 static u64 debugfs_atomic_t_get(void *data)
183 {
184         return atomic_read((atomic_t *)data);
185 }
186
187 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
188                         debugfs_atomic_t_set, "%lld\n");
189
190 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
191                                 struct dentry *parent, atomic_t *value)
192 {
193         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
194 }
195
196 void cleanup_fault_attr_dentries(struct fault_attr *attr)
197 {
198         debugfs_remove(attr->dentries.probability_file);
199         attr->dentries.probability_file = NULL;
200
201         debugfs_remove(attr->dentries.interval_file);
202         attr->dentries.interval_file = NULL;
203
204         debugfs_remove(attr->dentries.times_file);
205         attr->dentries.times_file = NULL;
206
207         debugfs_remove(attr->dentries.space_file);
208         attr->dentries.space_file = NULL;
209
210         debugfs_remove(attr->dentries.verbose_file);
211         attr->dentries.verbose_file = NULL;
212
213         debugfs_remove(attr->dentries.task_filter_file);
214         attr->dentries.task_filter_file = NULL;
215
216 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
217
218         debugfs_remove(attr->dentries.stacktrace_depth_file);
219         attr->dentries.stacktrace_depth_file = NULL;
220
221         debugfs_remove(attr->dentries.require_start_file);
222         attr->dentries.require_start_file = NULL;
223
224         debugfs_remove(attr->dentries.require_end_file);
225         attr->dentries.require_end_file = NULL;
226
227         debugfs_remove(attr->dentries.reject_start_file);
228         attr->dentries.reject_start_file = NULL;
229
230         debugfs_remove(attr->dentries.reject_end_file);
231         attr->dentries.reject_end_file = NULL;
232
233 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
234
235         if (attr->dentries.dir)
236                 WARN_ON(!simple_empty(attr->dentries.dir));
237
238         debugfs_remove(attr->dentries.dir);
239         attr->dentries.dir = NULL;
240 }
241
242 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
243 {
244         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
245         struct dentry *dir;
246
247         memset(&attr->dentries, 0, sizeof(attr->dentries));
248
249         dir = debugfs_create_dir(name, NULL);
250         if (!dir)
251                 goto fail;
252         attr->dentries.dir = dir;
253
254         attr->dentries.probability_file =
255                 debugfs_create_ul("probability", mode, dir, &attr->probability);
256
257         attr->dentries.interval_file =
258                 debugfs_create_ul("interval", mode, dir, &attr->interval);
259
260         attr->dentries.times_file =
261                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
262
263         attr->dentries.space_file =
264                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
265
266         attr->dentries.verbose_file =
267                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
268
269         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
270                                                 mode, dir, &attr->task_filter);
271
272         if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
273             !attr->dentries.times_file || !attr->dentries.space_file ||
274             !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
275                 goto fail;
276
277 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
278
279         attr->dentries.stacktrace_depth_file =
280                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
281                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
282
283         attr->dentries.require_start_file =
284                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
285
286         attr->dentries.require_end_file =
287                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
288
289         attr->dentries.reject_start_file =
290                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
291
292         attr->dentries.reject_end_file =
293                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
294
295         if (!attr->dentries.stacktrace_depth_file ||
296             !attr->dentries.require_start_file ||
297             !attr->dentries.require_end_file ||
298             !attr->dentries.reject_start_file ||
299             !attr->dentries.reject_end_file)
300                 goto fail;
301
302 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
303
304         return 0;
305 fail:
306         cleanup_fault_attr_dentries(attr);
307         return -ENOMEM;
308 }
309
310 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */