[PATCH] fault injection: split up stacktrace filter Kconfig option
[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         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         return true;
94 }
95
96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
97
98 /*
99  * This code is stolen from failmalloc-1.0
100  * http://www.nongnu.org/failmalloc/
101  */
102
103 bool should_fail(struct fault_attr *attr, ssize_t size)
104 {
105         if (attr->task_filter && !fail_task(attr, current))
106                 return false;
107
108         if (atomic_read(&attr->times) == 0)
109                 return false;
110
111         if (atomic_read(&attr->space) > size) {
112                 atomic_sub(size, &attr->space);
113                 return false;
114         }
115
116         if (attr->interval > 1) {
117                 attr->count++;
118                 if (attr->count % attr->interval)
119                         return false;
120         }
121
122         if (attr->probability <= random32() % 100)
123                 return false;
124
125         if (!fail_stacktrace(attr))
126                 return false;
127
128         fail_dump(attr);
129
130         if (atomic_read(&attr->times) != -1)
131                 atomic_dec_not_zero(&attr->times);
132
133         return true;
134 }
135
136 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
137
138 static void debugfs_ul_set(void *data, u64 val)
139 {
140         *(unsigned long *)data = val;
141 }
142
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
150 static u64 debugfs_ul_get(void *data)
151 {
152         return *(unsigned long *)data;
153 }
154
155 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
156
157 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
158                                 struct dentry *parent, unsigned long *value)
159 {
160         return debugfs_create_file(name, mode, parent, value, &fops_ul);
161 }
162
163 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
164                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
165
166 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
167         const char *name, mode_t mode,
168         struct dentry *parent, unsigned long *value)
169 {
170         return debugfs_create_file(name, mode, parent, value,
171                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
172 }
173
174 static void debugfs_atomic_t_set(void *data, u64 val)
175 {
176         atomic_set((atomic_t *)data, val);
177 }
178
179 static u64 debugfs_atomic_t_get(void *data)
180 {
181         return atomic_read((atomic_t *)data);
182 }
183
184 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
185                         debugfs_atomic_t_set, "%lld\n");
186
187 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
188                                 struct dentry *parent, atomic_t *value)
189 {
190         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
191 }
192
193 void cleanup_fault_attr_dentries(struct fault_attr *attr)
194 {
195         debugfs_remove(attr->dentries.probability_file);
196         attr->dentries.probability_file = NULL;
197
198         debugfs_remove(attr->dentries.interval_file);
199         attr->dentries.interval_file = NULL;
200
201         debugfs_remove(attr->dentries.times_file);
202         attr->dentries.times_file = NULL;
203
204         debugfs_remove(attr->dentries.space_file);
205         attr->dentries.space_file = NULL;
206
207         debugfs_remove(attr->dentries.verbose_file);
208         attr->dentries.verbose_file = NULL;
209
210         debugfs_remove(attr->dentries.task_filter_file);
211         attr->dentries.task_filter_file = NULL;
212
213 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
214
215         debugfs_remove(attr->dentries.stacktrace_depth_file);
216         attr->dentries.stacktrace_depth_file = NULL;
217
218         debugfs_remove(attr->dentries.require_start_file);
219         attr->dentries.require_start_file = NULL;
220
221         debugfs_remove(attr->dentries.require_end_file);
222         attr->dentries.require_end_file = NULL;
223
224         debugfs_remove(attr->dentries.reject_start_file);
225         attr->dentries.reject_start_file = NULL;
226
227         debugfs_remove(attr->dentries.reject_end_file);
228         attr->dentries.reject_end_file = NULL;
229
230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
231
232         if (attr->dentries.dir)
233                 WARN_ON(!simple_empty(attr->dentries.dir));
234
235         debugfs_remove(attr->dentries.dir);
236         attr->dentries.dir = NULL;
237 }
238
239 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
240 {
241         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
242         struct dentry *dir;
243
244         memset(&attr->dentries, 0, sizeof(attr->dentries));
245
246         dir = debugfs_create_dir(name, NULL);
247         if (!dir)
248                 goto fail;
249         attr->dentries.dir = dir;
250
251         attr->dentries.probability_file =
252                 debugfs_create_ul("probability", mode, dir, &attr->probability);
253
254         attr->dentries.interval_file =
255                 debugfs_create_ul("interval", mode, dir, &attr->interval);
256
257         attr->dentries.times_file =
258                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
259
260         attr->dentries.space_file =
261                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
262
263         attr->dentries.verbose_file =
264                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
265
266         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
267                                                 mode, dir, &attr->task_filter);
268
269         if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
270             !attr->dentries.times_file || !attr->dentries.space_file ||
271             !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
272                 goto fail;
273
274 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
275
276         attr->dentries.stacktrace_depth_file =
277                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
278                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
279
280         attr->dentries.require_start_file =
281                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
282
283         attr->dentries.require_end_file =
284                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
285
286         attr->dentries.reject_start_file =
287                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
288
289         attr->dentries.reject_end_file =
290                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
291
292         if (!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                 goto fail;
298
299 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
300
301         return 0;
302 fail:
303         cleanup_fault_attr_dentries(attr);
304         return -ENOMEM;
305 }
306
307 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */