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 */