[PATCH] clocksource: fixup is_continous changes on ARM
[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 #if defined(CONFIG_STACKTRACE)
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         trace.all_contexts = 0;
76
77         save_stack_trace(&trace, NULL);
78         for (n = 0; n < trace.nr_entries; n++) {
79                 if (attr->reject_start <= entries[n] &&
80                                entries[n] < attr->reject_end)
81                         return false;
82                 if (attr->require_start <= entries[n] &&
83                                entries[n] < attr->require_end)
84                         found = true;
85         }
86         return found;
87 }
88
89 #else
90
91 static inline bool fail_stacktrace(struct fault_attr *attr)
92 {
93         static bool firsttime = true;
94
95         if (firsttime) {
96                 printk(KERN_WARNING
97                 "This architecture does not implement save_stack_trace()\n");
98                 firsttime = false;
99         }
100         return false;
101 }
102
103 #endif
104
105 /*
106  * This code is stolen from failmalloc-1.0
107  * http://www.nongnu.org/failmalloc/
108  */
109
110 bool should_fail(struct fault_attr *attr, ssize_t size)
111 {
112         if (attr->task_filter && !fail_task(attr, current))
113                 return false;
114
115         if (atomic_read(&attr->times) == 0)
116                 return false;
117
118         if (atomic_read(&attr->space) > size) {
119                 atomic_sub(size, &attr->space);
120                 return false;
121         }
122
123         if (attr->interval > 1) {
124                 attr->count++;
125                 if (attr->count % attr->interval)
126                         return false;
127         }
128
129         if (attr->probability <= random32() % 100)
130                 return false;
131
132         if (!fail_stacktrace(attr))
133                 return false;
134
135         fail_dump(attr);
136
137         if (atomic_read(&attr->times) != -1)
138                 atomic_dec_not_zero(&attr->times);
139
140         return true;
141 }
142
143 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
144
145 static void debugfs_ul_set(void *data, u64 val)
146 {
147         *(unsigned long *)data = val;
148 }
149
150 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
151 {
152         *(unsigned long *)data =
153                 val < MAX_STACK_TRACE_DEPTH ?
154                 val : MAX_STACK_TRACE_DEPTH;
155 }
156
157 static u64 debugfs_ul_get(void *data)
158 {
159         return *(unsigned long *)data;
160 }
161
162 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
163
164 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
165                                 struct dentry *parent, unsigned long *value)
166 {
167         return debugfs_create_file(name, mode, parent, value, &fops_ul);
168 }
169
170 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
171                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
172
173 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
174         const char *name, mode_t mode,
175         struct dentry *parent, unsigned long *value)
176 {
177         return debugfs_create_file(name, mode, parent, value,
178                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
179 }
180
181 static void debugfs_atomic_t_set(void *data, u64 val)
182 {
183         atomic_set((atomic_t *)data, val);
184 }
185
186 static u64 debugfs_atomic_t_get(void *data)
187 {
188         return atomic_read((atomic_t *)data);
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 void cleanup_fault_attr_dentries(struct fault_attr *attr)
201 {
202         debugfs_remove(attr->dentries.probability_file);
203         attr->dentries.probability_file = NULL;
204
205         debugfs_remove(attr->dentries.interval_file);
206         attr->dentries.interval_file = NULL;
207
208         debugfs_remove(attr->dentries.times_file);
209         attr->dentries.times_file = NULL;
210
211         debugfs_remove(attr->dentries.space_file);
212         attr->dentries.space_file = NULL;
213
214         debugfs_remove(attr->dentries.verbose_file);
215         attr->dentries.verbose_file = NULL;
216
217         debugfs_remove(attr->dentries.task_filter_file);
218         attr->dentries.task_filter_file = NULL;
219
220         debugfs_remove(attr->dentries.stacktrace_depth_file);
221         attr->dentries.stacktrace_depth_file = NULL;
222
223         debugfs_remove(attr->dentries.require_start_file);
224         attr->dentries.require_start_file = NULL;
225
226         debugfs_remove(attr->dentries.require_end_file);
227         attr->dentries.require_end_file = NULL;
228
229         debugfs_remove(attr->dentries.reject_start_file);
230         attr->dentries.reject_start_file = NULL;
231
232         debugfs_remove(attr->dentries.reject_end_file);
233         attr->dentries.reject_end_file = NULL;
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         attr->dentries.stacktrace_depth_file =
273                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
274                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
275
276         attr->dentries.require_start_file =
277                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
278
279         attr->dentries.require_end_file =
280                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
281
282         attr->dentries.reject_start_file =
283                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
284
285         attr->dentries.reject_end_file =
286                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
287
288
289         if (!attr->dentries.probability_file || !attr->dentries.interval_file
290             || !attr->dentries.times_file || !attr->dentries.space_file
291             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
292             || !attr->dentries.stacktrace_depth_file
293             || !attr->dentries.require_start_file
294             || !attr->dentries.require_end_file
295             || !attr->dentries.reject_start_file
296             || !attr->dentries.reject_end_file
297             )
298                 goto fail;
299
300         return 0;
301 fail:
302         cleanup_fault_attr_dentries(attr);
303         return -ENOMEM;
304 }
305
306 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */