Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6
[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/stacktrace.h>
10 #include <linux/kallsyms.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, &times) < 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 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
143 static int 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         return 0;
149 }
150 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
151
152 static int debugfs_ul_get(void *data, u64 *val)
153 {
154         *val = *(unsigned long *)data;
155         return 0;
156 }
157
158 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
159
160 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
161                                 struct dentry *parent, unsigned long *value)
162 {
163         return debugfs_create_file(name, mode, parent, value, &fops_ul);
164 }
165
166 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
167 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
168                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
169
170 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
171         const char *name, mode_t mode,
172         struct dentry *parent, unsigned long *value)
173 {
174         return debugfs_create_file(name, mode, parent, value,
175                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
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 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 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221
222         debugfs_remove(attr->dentries.stacktrace_depth_file);
223         attr->dentries.stacktrace_depth_file = NULL;
224
225         debugfs_remove(attr->dentries.require_start_file);
226         attr->dentries.require_start_file = NULL;
227
228         debugfs_remove(attr->dentries.require_end_file);
229         attr->dentries.require_end_file = NULL;
230
231         debugfs_remove(attr->dentries.reject_start_file);
232         attr->dentries.reject_start_file = NULL;
233
234         debugfs_remove(attr->dentries.reject_end_file);
235         attr->dentries.reject_end_file = NULL;
236
237 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
238
239         if (attr->dentries.dir)
240                 WARN_ON(!simple_empty(attr->dentries.dir));
241
242         debugfs_remove(attr->dentries.dir);
243         attr->dentries.dir = NULL;
244 }
245
246 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
247 {
248         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
249         struct dentry *dir;
250
251         memset(&attr->dentries, 0, sizeof(attr->dentries));
252
253         dir = debugfs_create_dir(name, NULL);
254         if (!dir)
255                 goto fail;
256         attr->dentries.dir = dir;
257
258         attr->dentries.probability_file =
259                 debugfs_create_ul("probability", mode, dir, &attr->probability);
260
261         attr->dentries.interval_file =
262                 debugfs_create_ul("interval", mode, dir, &attr->interval);
263
264         attr->dentries.times_file =
265                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
266
267         attr->dentries.space_file =
268                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
269
270         attr->dentries.verbose_file =
271                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
272
273         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
274                                                 mode, dir, &attr->task_filter);
275
276         if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
277             !attr->dentries.times_file || !attr->dentries.space_file ||
278             !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
279                 goto fail;
280
281 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
282
283         attr->dentries.stacktrace_depth_file =
284                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
285                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
286
287         attr->dentries.require_start_file =
288                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
289
290         attr->dentries.require_end_file =
291                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
292
293         attr->dentries.reject_start_file =
294                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
295
296         attr->dentries.reject_end_file =
297                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
298
299         if (!attr->dentries.stacktrace_depth_file ||
300             !attr->dentries.require_start_file ||
301             !attr->dentries.require_end_file ||
302             !attr->dentries.reject_start_file ||
303             !attr->dentries.reject_end_file)
304                 goto fail;
305
306 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
307
308         return 0;
309 fail:
310         cleanup_fault_attr_dentries(attr);
311         return -ENOMEM;
312 }
313
314 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */