Linux Kernel  3.7.1
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fault-inject.c
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1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <linux/random.h>
4 #include <linux/sched.h>
5 #include <linux/stat.h>
6 #include <linux/types.h>
7 #include <linux/fs.h>
8 #include <linux/export.h>
9 #include <linux/interrupt.h>
10 #include <linux/stacktrace.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 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) {
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 }
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  /* No need to check any other properties if the probability is 0 */
105  if (attr->probability == 0)
106  return false;
107 
108  if (attr->task_filter && !fail_task(attr, current))
109  return false;
110 
111  if (atomic_read(&attr->times) == 0)
112  return false;
113 
114  if (atomic_read(&attr->space) > size) {
115  atomic_sub(size, &attr->space);
116  return false;
117  }
118 
119  if (attr->interval > 1) {
120  attr->count++;
121  if (attr->count % attr->interval)
122  return false;
123  }
124 
125  if (attr->probability <= random32() % 100)
126  return false;
127 
128  if (!fail_stacktrace(attr))
129  return false;
130 
131  fail_dump(attr);
132 
133  if (atomic_read(&attr->times) != -1)
134  atomic_dec_not_zero(&attr->times);
135 
136  return true;
137 }
139 
140 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
141 
142 static int debugfs_ul_set(void *data, u64 val)
143 {
144  *(unsigned long *)data = val;
145  return 0;
146 }
147 
148 static int debugfs_ul_get(void *data, u64 *val)
149 {
150  *val = *(unsigned long *)data;
151  return 0;
152 }
153 
154 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
155 
156 static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
157  struct dentry *parent, unsigned long *value)
158 {
159  return debugfs_create_file(name, mode, parent, value, &fops_ul);
160 }
161 
162 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
163 
164 static int debugfs_stacktrace_depth_set(void *data, u64 val)
165 {
166  *(unsigned long *)data =
167  min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
168 
169  return 0;
170 }
171 
172 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
173  debugfs_stacktrace_depth_set, "%llu\n");
174 
175 static struct dentry *debugfs_create_stacktrace_depth(
176  const char *name, umode_t mode,
177  struct dentry *parent, unsigned long *value)
178 {
179  return debugfs_create_file(name, mode, parent, value,
180  &fops_stacktrace_depth);
181 }
182 
183 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
184 
185 static int debugfs_atomic_t_set(void *data, u64 val)
186 {
187  atomic_set((atomic_t *)data, val);
188  return 0;
189 }
190 
191 static int debugfs_atomic_t_get(void *data, u64 *val)
192 {
193  *val = atomic_read((atomic_t *)data);
194  return 0;
195 }
196 
197 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
198  debugfs_atomic_t_set, "%lld\n");
199 
200 static struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
201  struct dentry *parent, atomic_t *value)
202 {
203  return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
204 }
205 
206 struct dentry *fault_create_debugfs_attr(const char *name,
207  struct dentry *parent, struct fault_attr *attr)
208 {
210  struct dentry *dir;
211 
212  dir = debugfs_create_dir(name, parent);
213  if (!dir)
214  return ERR_PTR(-ENOMEM);
215 
216  if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
217  goto fail;
218  if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
219  goto fail;
220  if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
221  goto fail;
222  if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
223  goto fail;
224  if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
225  goto fail;
226  if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
227  goto fail;
228 
229 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
230 
231  if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
232  &attr->stacktrace_depth))
233  goto fail;
234  if (!debugfs_create_ul("require-start", mode, dir,
235  &attr->require_start))
236  goto fail;
237  if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
238  goto fail;
239  if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
240  goto fail;
241  if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
242  goto fail;
243 
244 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
245 
246  return dir;
247 fail:
249 
250  return ERR_PTR(-ENOMEM);
251 }
252 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
253 
254 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */