fault-inject.c 7.6 KB

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  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. * 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. /* "<interval>,<probability>,<space>,<times>" */
  24. if (sscanf(str, "%lu,%lu,%d,%d",
  25. &interval, &probability, &space, &times) < 4) {
  26. printk(KERN_WARNING
  27. "FAULT_INJECTION: failed to parse arguments\n");
  28. return 0;
  29. }
  30. attr->probability = probability;
  31. attr->interval = interval;
  32. atomic_set(&attr->times, times);
  33. atomic_set(&attr->space, space);
  34. return 1;
  35. }
  36. static void fail_dump(struct fault_attr *attr)
  37. {
  38. if (attr->verbose > 0)
  39. printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
  40. if (attr->verbose > 1)
  41. dump_stack();
  42. }
  43. #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
  44. static bool fail_task(struct fault_attr *attr, struct task_struct *task)
  45. {
  46. return !in_interrupt() && task->make_it_fail;
  47. }
  48. #define MAX_STACK_TRACE_DEPTH 32
  49. #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
  50. static bool fail_stacktrace(struct fault_attr *attr)
  51. {
  52. struct stack_trace trace;
  53. int depth = attr->stacktrace_depth;
  54. unsigned long entries[MAX_STACK_TRACE_DEPTH];
  55. int n;
  56. bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
  57. if (depth == 0)
  58. return found;
  59. trace.nr_entries = 0;
  60. trace.entries = entries;
  61. trace.max_entries = depth;
  62. trace.skip = 1;
  63. trace.all_contexts = 0;
  64. save_stack_trace(&trace, NULL);
  65. for (n = 0; n < trace.nr_entries; n++) {
  66. if (attr->reject_start <= entries[n] &&
  67. entries[n] < attr->reject_end)
  68. return false;
  69. if (attr->require_start <= entries[n] &&
  70. entries[n] < attr->require_end)
  71. found = true;
  72. }
  73. return found;
  74. }
  75. #else
  76. static inline bool fail_stacktrace(struct fault_attr *attr)
  77. {
  78. return true;
  79. }
  80. #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
  81. /*
  82. * This code is stolen from failmalloc-1.0
  83. * http://www.nongnu.org/failmalloc/
  84. */
  85. bool should_fail(struct fault_attr *attr, ssize_t size)
  86. {
  87. if (attr->task_filter && !fail_task(attr, current))
  88. return false;
  89. if (atomic_read(&attr->times) == 0)
  90. return false;
  91. if (atomic_read(&attr->space) > size) {
  92. atomic_sub(size, &attr->space);
  93. return false;
  94. }
  95. if (attr->interval > 1) {
  96. attr->count++;
  97. if (attr->count % attr->interval)
  98. return false;
  99. }
  100. if (attr->probability <= random32() % 100)
  101. return false;
  102. if (!fail_stacktrace(attr))
  103. return false;
  104. fail_dump(attr);
  105. if (atomic_read(&attr->times) != -1)
  106. atomic_dec_not_zero(&attr->times);
  107. return true;
  108. }
  109. #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
  110. static void debugfs_ul_set(void *data, u64 val)
  111. {
  112. *(unsigned long *)data = val;
  113. }
  114. static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
  115. {
  116. *(unsigned long *)data =
  117. val < MAX_STACK_TRACE_DEPTH ?
  118. val : MAX_STACK_TRACE_DEPTH;
  119. }
  120. static u64 debugfs_ul_get(void *data)
  121. {
  122. return *(unsigned long *)data;
  123. }
  124. DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
  125. static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
  126. struct dentry *parent, unsigned long *value)
  127. {
  128. return debugfs_create_file(name, mode, parent, value, &fops_ul);
  129. }
  130. DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
  131. debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
  132. static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
  133. const char *name, mode_t mode,
  134. struct dentry *parent, unsigned long *value)
  135. {
  136. return debugfs_create_file(name, mode, parent, value,
  137. &fops_ul_MAX_STACK_TRACE_DEPTH);
  138. }
  139. static void debugfs_atomic_t_set(void *data, u64 val)
  140. {
  141. atomic_set((atomic_t *)data, val);
  142. }
  143. static u64 debugfs_atomic_t_get(void *data)
  144. {
  145. return atomic_read((atomic_t *)data);
  146. }
  147. DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
  148. debugfs_atomic_t_set, "%lld\n");
  149. static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
  150. struct dentry *parent, atomic_t *value)
  151. {
  152. return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
  153. }
  154. void cleanup_fault_attr_dentries(struct fault_attr *attr)
  155. {
  156. debugfs_remove(attr->dentries.probability_file);
  157. attr->dentries.probability_file = NULL;
  158. debugfs_remove(attr->dentries.interval_file);
  159. attr->dentries.interval_file = NULL;
  160. debugfs_remove(attr->dentries.times_file);
  161. attr->dentries.times_file = NULL;
  162. debugfs_remove(attr->dentries.space_file);
  163. attr->dentries.space_file = NULL;
  164. debugfs_remove(attr->dentries.verbose_file);
  165. attr->dentries.verbose_file = NULL;
  166. debugfs_remove(attr->dentries.task_filter_file);
  167. attr->dentries.task_filter_file = NULL;
  168. #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
  169. debugfs_remove(attr->dentries.stacktrace_depth_file);
  170. attr->dentries.stacktrace_depth_file = NULL;
  171. debugfs_remove(attr->dentries.require_start_file);
  172. attr->dentries.require_start_file = NULL;
  173. debugfs_remove(attr->dentries.require_end_file);
  174. attr->dentries.require_end_file = NULL;
  175. debugfs_remove(attr->dentries.reject_start_file);
  176. attr->dentries.reject_start_file = NULL;
  177. debugfs_remove(attr->dentries.reject_end_file);
  178. attr->dentries.reject_end_file = NULL;
  179. #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
  180. if (attr->dentries.dir)
  181. WARN_ON(!simple_empty(attr->dentries.dir));
  182. debugfs_remove(attr->dentries.dir);
  183. attr->dentries.dir = NULL;
  184. }
  185. int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
  186. {
  187. mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
  188. struct dentry *dir;
  189. memset(&attr->dentries, 0, sizeof(attr->dentries));
  190. dir = debugfs_create_dir(name, NULL);
  191. if (!dir)
  192. goto fail;
  193. attr->dentries.dir = dir;
  194. attr->dentries.probability_file =
  195. debugfs_create_ul("probability", mode, dir, &attr->probability);
  196. attr->dentries.interval_file =
  197. debugfs_create_ul("interval", mode, dir, &attr->interval);
  198. attr->dentries.times_file =
  199. debugfs_create_atomic_t("times", mode, dir, &attr->times);
  200. attr->dentries.space_file =
  201. debugfs_create_atomic_t("space", mode, dir, &attr->space);
  202. attr->dentries.verbose_file =
  203. debugfs_create_ul("verbose", mode, dir, &attr->verbose);
  204. attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
  205. mode, dir, &attr->task_filter);
  206. if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
  207. !attr->dentries.times_file || !attr->dentries.space_file ||
  208. !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
  209. goto fail;
  210. #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
  211. attr->dentries.stacktrace_depth_file =
  212. debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
  213. "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
  214. attr->dentries.require_start_file =
  215. debugfs_create_ul("require-start", mode, dir, &attr->require_start);
  216. attr->dentries.require_end_file =
  217. debugfs_create_ul("require-end", mode, dir, &attr->require_end);
  218. attr->dentries.reject_start_file =
  219. debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
  220. attr->dentries.reject_end_file =
  221. debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
  222. if (!attr->dentries.stacktrace_depth_file ||
  223. !attr->dentries.require_start_file ||
  224. !attr->dentries.require_end_file ||
  225. !attr->dentries.reject_start_file ||
  226. !attr->dentries.reject_end_file)
  227. goto fail;
  228. #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
  229. return 0;
  230. fail:
  231. cleanup_fault_attr_dentries(attr);
  232. return -ENOMEM;
  233. }
  234. #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */