[PATCH] fault-injection: optimize and simplify should_fail()
[linux-3.10.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_STACK_UNWIND
59
60 static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
61                                                 void *arg)
62 {
63         int depth;
64         struct fault_attr *attr = arg;
65         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
66
67         for (depth = 0; depth < attr->stacktrace_depth
68                         && unwind(info) == 0 && UNW_PC(info); depth++) {
69                 if (arch_unw_user_mode(info))
70                         break;
71                 if (attr->reject_start <= UNW_PC(info) &&
72                                UNW_PC(info) < attr->reject_end)
73                         return false;
74                 if (attr->require_start <= UNW_PC(info) &&
75                                UNW_PC(info) < attr->require_end)
76                         found = true;
77         }
78         return found;
79 }
80
81 static bool fail_stacktrace(struct fault_attr *attr)
82 {
83         struct unwind_frame_info info;
84
85         return unwind_init_running(&info, fail_stacktrace_callback, attr);
86 }
87
88 #elif defined(CONFIG_STACKTRACE)
89
90 static bool fail_stacktrace(struct fault_attr *attr)
91 {
92         struct stack_trace trace;
93         int depth = attr->stacktrace_depth;
94         unsigned long entries[MAX_STACK_TRACE_DEPTH];
95         int n;
96         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
97
98         if (depth == 0)
99                 return found;
100
101         trace.nr_entries = 0;
102         trace.entries = entries;
103         trace.max_entries = depth;
104         trace.skip = 1;
105         trace.all_contexts = 0;
106
107         save_stack_trace(&trace, NULL);
108         for (n = 0; n < trace.nr_entries; n++) {
109                 if (attr->reject_start <= entries[n] &&
110                                entries[n] < attr->reject_end)
111                         return false;
112                 if (attr->require_start <= entries[n] &&
113                                entries[n] < attr->require_end)
114                         found = true;
115         }
116         return found;
117 }
118
119 #else
120
121 static inline bool fail_stacktrace(struct fault_attr *attr)
122 {
123         static bool firsttime = true;
124
125         if (firsttime) {
126                 printk(KERN_WARNING
127                 "This architecture does not implement save_stack_trace()\n");
128                 firsttime = false;
129         }
130         return false;
131 }
132
133 #endif
134
135 /*
136  * This code is stolen from failmalloc-1.0
137  * http://www.nongnu.org/failmalloc/
138  */
139
140 bool should_fail(struct fault_attr *attr, ssize_t size)
141 {
142         if (attr->task_filter && !fail_task(attr, current))
143                 return false;
144
145         if (atomic_read(&attr->times) == 0)
146                 return false;
147
148         if (atomic_read(&attr->space) > size) {
149                 atomic_sub(size, &attr->space);
150                 return false;
151         }
152
153         if (attr->interval > 1) {
154                 attr->count++;
155                 if (attr->count % attr->interval)
156                         return false;
157         }
158
159         if (attr->probability <= random32() % 100)
160                 return false;
161
162         if (!fail_stacktrace(attr))
163                 return false;
164
165         fail_dump(attr);
166
167         if (atomic_read(&attr->times) != -1)
168                 atomic_dec_not_zero(&attr->times);
169
170         return true;
171 }
172
173 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
174
175 static void debugfs_ul_set(void *data, u64 val)
176 {
177         *(unsigned long *)data = val;
178 }
179
180 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
181 {
182         *(unsigned long *)data =
183                 val < MAX_STACK_TRACE_DEPTH ?
184                 val : MAX_STACK_TRACE_DEPTH;
185 }
186
187 static u64 debugfs_ul_get(void *data)
188 {
189         return *(unsigned long *)data;
190 }
191
192 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
193
194 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
195                                 struct dentry *parent, unsigned long *value)
196 {
197         return debugfs_create_file(name, mode, parent, value, &fops_ul);
198 }
199
200 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
201                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
202
203 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
204         const char *name, mode_t mode,
205         struct dentry *parent, unsigned long *value)
206 {
207         return debugfs_create_file(name, mode, parent, value,
208                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
209 }
210
211 static void debugfs_atomic_t_set(void *data, u64 val)
212 {
213         atomic_set((atomic_t *)data, val);
214 }
215
216 static u64 debugfs_atomic_t_get(void *data)
217 {
218         return atomic_read((atomic_t *)data);
219 }
220
221 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
222                         debugfs_atomic_t_set, "%lld\n");
223
224 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
225                                 struct dentry *parent, atomic_t *value)
226 {
227         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
228 }
229
230 void cleanup_fault_attr_dentries(struct fault_attr *attr)
231 {
232         debugfs_remove(attr->dentries.probability_file);
233         attr->dentries.probability_file = NULL;
234
235         debugfs_remove(attr->dentries.interval_file);
236         attr->dentries.interval_file = NULL;
237
238         debugfs_remove(attr->dentries.times_file);
239         attr->dentries.times_file = NULL;
240
241         debugfs_remove(attr->dentries.space_file);
242         attr->dentries.space_file = NULL;
243
244         debugfs_remove(attr->dentries.verbose_file);
245         attr->dentries.verbose_file = NULL;
246
247         debugfs_remove(attr->dentries.task_filter_file);
248         attr->dentries.task_filter_file = NULL;
249
250         debugfs_remove(attr->dentries.stacktrace_depth_file);
251         attr->dentries.stacktrace_depth_file = NULL;
252
253         debugfs_remove(attr->dentries.require_start_file);
254         attr->dentries.require_start_file = NULL;
255
256         debugfs_remove(attr->dentries.require_end_file);
257         attr->dentries.require_end_file = NULL;
258
259         debugfs_remove(attr->dentries.reject_start_file);
260         attr->dentries.reject_start_file = NULL;
261
262         debugfs_remove(attr->dentries.reject_end_file);
263         attr->dentries.reject_end_file = NULL;
264
265         if (attr->dentries.dir)
266                 WARN_ON(!simple_empty(attr->dentries.dir));
267
268         debugfs_remove(attr->dentries.dir);
269         attr->dentries.dir = NULL;
270 }
271
272 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
273 {
274         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
275         struct dentry *dir;
276
277         memset(&attr->dentries, 0, sizeof(attr->dentries));
278
279         dir = debugfs_create_dir(name, NULL);
280         if (!dir)
281                 goto fail;
282         attr->dentries.dir = dir;
283
284         attr->dentries.probability_file =
285                 debugfs_create_ul("probability", mode, dir, &attr->probability);
286
287         attr->dentries.interval_file =
288                 debugfs_create_ul("interval", mode, dir, &attr->interval);
289
290         attr->dentries.times_file =
291                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
292
293         attr->dentries.space_file =
294                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
295
296         attr->dentries.verbose_file =
297                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
298
299         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
300                                                 mode, dir, &attr->task_filter);
301
302         attr->dentries.stacktrace_depth_file =
303                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
304                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
305
306         attr->dentries.require_start_file =
307                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
308
309         attr->dentries.require_end_file =
310                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
311
312         attr->dentries.reject_start_file =
313                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
314
315         attr->dentries.reject_end_file =
316                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
317
318
319         if (!attr->dentries.probability_file || !attr->dentries.interval_file
320             || !attr->dentries.times_file || !attr->dentries.space_file
321             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
322             || !attr->dentries.stacktrace_depth_file
323             || !attr->dentries.require_start_file
324             || !attr->dentries.require_end_file
325             || !attr->dentries.reject_start_file
326             || !attr->dentries.reject_end_file
327             )
328                 goto fail;
329
330         return 0;
331 fail:
332         cleanup_fault_attr_dentries(attr);
333         return -ENOMEM;
334 }
335
336 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */