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Linux/lib/fault-inject.c

  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) {
 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 EXPORT_SYMBOL_GPL(setup_fault_attr);
 40 
 41 static void fail_dump(struct fault_attr *attr)
 42 {
 43         if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
 44                 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
 45                        "name %pd, interval %lu, probability %lu, "
 46                        "space %d, times %d\n", attr->dname,
 47                        attr->interval, attr->probability,
 48                        atomic_read(&attr->space),
 49                        atomic_read(&attr->times));
 50                 if (attr->verbose > 1)
 51                         dump_stack();
 52         }
 53 }
 54 
 55 #define atomic_dec_not_zero(v)          atomic_add_unless((v), -1, 0)
 56 
 57 static bool fail_task(struct fault_attr *attr, struct task_struct *task)
 58 {
 59         return !in_interrupt() && task->make_it_fail;
 60 }
 61 
 62 #define MAX_STACK_TRACE_DEPTH 32
 63 
 64 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 65 
 66 static bool fail_stacktrace(struct fault_attr *attr)
 67 {
 68         struct stack_trace trace;
 69         int depth = attr->stacktrace_depth;
 70         unsigned long entries[MAX_STACK_TRACE_DEPTH];
 71         int n;
 72         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
 73 
 74         if (depth == 0)
 75                 return found;
 76 
 77         trace.nr_entries = 0;
 78         trace.entries = entries;
 79         trace.max_entries = depth;
 80         trace.skip = 1;
 81 
 82         save_stack_trace(&trace);
 83         for (n = 0; n < trace.nr_entries; n++) {
 84                 if (attr->reject_start <= entries[n] &&
 85                                entries[n] < attr->reject_end)
 86                         return false;
 87                 if (attr->require_start <= entries[n] &&
 88                                entries[n] < attr->require_end)
 89                         found = true;
 90         }
 91         return found;
 92 }
 93 
 94 #else
 95 
 96 static inline bool fail_stacktrace(struct fault_attr *attr)
 97 {
 98         return true;
 99 }
100 
101 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
102 
103 /*
104  * This code is stolen from failmalloc-1.0
105  * http://www.nongnu.org/failmalloc/
106  */
107 
108 bool should_fail(struct fault_attr *attr, ssize_t size)
109 {
110         /* No need to check any other properties if the probability is 0 */
111         if (attr->probability == 0)
112                 return false;
113 
114         if (attr->task_filter && !fail_task(attr, current))
115                 return false;
116 
117         if (atomic_read(&attr->times) == 0)
118                 return false;
119 
120         if (atomic_read(&attr->space) > size) {
121                 atomic_sub(size, &attr->space);
122                 return false;
123         }
124 
125         if (attr->interval > 1) {
126                 attr->count++;
127                 if (attr->count % attr->interval)
128                         return false;
129         }
130 
131         if (attr->probability <= prandom_u32() % 100)
132                 return false;
133 
134         if (!fail_stacktrace(attr))
135                 return false;
136 
137         fail_dump(attr);
138 
139         if (atomic_read(&attr->times) != -1)
140                 atomic_dec_not_zero(&attr->times);
141 
142         return true;
143 }
144 EXPORT_SYMBOL_GPL(should_fail);
145 
146 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
147 
148 static int debugfs_ul_set(void *data, u64 val)
149 {
150         *(unsigned long *)data = val;
151         return 0;
152 }
153 
154 static int debugfs_ul_get(void *data, u64 *val)
155 {
156         *val = *(unsigned long *)data;
157         return 0;
158 }
159 
160 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
161 
162 static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
163                                 struct dentry *parent, unsigned long *value)
164 {
165         return debugfs_create_file(name, mode, parent, value, &fops_ul);
166 }
167 
168 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
169 
170 static int debugfs_stacktrace_depth_set(void *data, u64 val)
171 {
172         *(unsigned long *)data =
173                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
174 
175         return 0;
176 }
177 
178 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
179                         debugfs_stacktrace_depth_set, "%llu\n");
180 
181 static struct dentry *debugfs_create_stacktrace_depth(
182         const char *name, umode_t mode,
183         struct dentry *parent, unsigned long *value)
184 {
185         return debugfs_create_file(name, mode, parent, value,
186                                    &fops_stacktrace_depth);
187 }
188 
189 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
190 
191 struct dentry *fault_create_debugfs_attr(const char *name,
192                         struct dentry *parent, struct fault_attr *attr)
193 {
194         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
195         struct dentry *dir;
196 
197         dir = debugfs_create_dir(name, parent);
198         if (!dir)
199                 return ERR_PTR(-ENOMEM);
200 
201         if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
202                 goto fail;
203         if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
204                 goto fail;
205         if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
206                 goto fail;
207         if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
208                 goto fail;
209         if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
210                 goto fail;
211         if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
212                                 &attr->ratelimit_state.interval))
213                 goto fail;
214         if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
215                                 &attr->ratelimit_state.burst))
216                 goto fail;
217         if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
218                 goto fail;
219 
220 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221 
222         if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
223                                 &attr->stacktrace_depth))
224                 goto fail;
225         if (!debugfs_create_ul("require-start", mode, dir,
226                                 &attr->require_start))
227                 goto fail;
228         if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
229                 goto fail;
230         if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
231                 goto fail;
232         if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
233                 goto fail;
234 
235 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
236 
237         attr->dname = dget(dir);
238         return dir;
239 fail:
240         debugfs_remove_recursive(dir);
241 
242         return ERR_PTR(-ENOMEM);
243 }
244 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
245 
246 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
247 

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