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_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         trace.all_contexts = 0;
  76
  77         save_stack_trace(&trace, NULL);
  78         for (n = 0; n < trace.nr_entries; n++) {
  79                 if (attr->reject_start <= entries[n] &&
  80                                entries[n] < attr->reject_end)
  81                         return false;
  82                 if (attr->require_start <= entries[n] &&
  83                                entries[n] < attr->require_end)
  84                         found = true;
  85         }
  86         return found;
  87 }
  88
  89 #else
  90
  91 static inline bool fail_stacktrace(struct fault_attr *attr)
  92 {
  93         return true;
  94 }
  95
  96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
  97
  98 /*
  99  * This code is stolen from failmalloc-1.0
 100  * http://www.nongnu.org/failmalloc/
 101  */
 102
 103 bool should_fail(struct fault_attr *attr, ssize_t size)
 104 {
 105         if (attr->task_filter && !fail_task(attr, current))
 106                 return false;
 107
 108         if (atomic_read(&attr->times) == 0)
 109                 return false;
 110
 111         if (atomic_read(&attr->space) > size) {
 112                 atomic_sub(size, &attr->space);
 113                 return false;
 114         }
 115
 116         if (attr->interval > 1) {
 117                 attr->count++;
 118                 if (attr->count % attr->interval)
 119                         return false;
 120         }
 121
 122         if (attr->probability <= random32() % 100)
 123                 return false;
 124
 125         if (!fail_stacktrace(attr))
 126                 return false;
 127
 128         fail_dump(attr);
 129
 130         if (atomic_read(&attr->times) != -1)
 131                 atomic_dec_not_zero(&attr->times);
 132
 133         return true;
 134 }
 135
 136 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 137
 138 static void debugfs_ul_set(void *data, u64 val)
 139 {
 140         *(unsigned long *)data = val;
 141 }
 142
 143 static void 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 }
 149
 150 static u64 debugfs_ul_get(void *data)
 151 {
 152         return *(unsigned long *)data;
 153 }
 154
 155 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 156
 157 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 158                                 struct dentry *parent, unsigned long *value)
 159 {
 160         return debugfs_create_file(name, mode, parent, value, &fops_ul);
 161 }
 162
 163 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
 164                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
 165
 166 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 167         const char *name, mode_t mode,
 168         struct dentry *parent, unsigned long *value)
 169 {
 170         return debugfs_create_file(name, mode, parent, value,
 171                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
 172 }
 173
 174 static void debugfs_atomic_t_set(void *data, u64 val)
 175 {
 176         atomic_set((atomic_t *)data, val);
 177 }
 178
 179 static u64 debugfs_atomic_t_get(void *data)
 180 {
 181         return atomic_read((atomic_t *)data);
 182 }
 183
 184 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
 185                         debugfs_atomic_t_set, "%lld\n");
 186
 187 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 188                                 struct dentry *parent, atomic_t *value)
 189 {
 190         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 191 }
 192
 193 void cleanup_fault_attr_dentries(struct fault_attr *attr)
 194 {
 195         debugfs_remove(attr->dentries.probability_file);
 196         attr->dentries.probability_file = NULL;
 197
 198         debugfs_remove(attr->dentries.interval_file);
 199         attr->dentries.interval_file = NULL;
 200
 201         debugfs_remove(attr->dentries.times_file);
 202         attr->dentries.times_file = NULL;
 203
 204         debugfs_remove(attr->dentries.space_file);
 205         attr->dentries.space_file = NULL;
 206
 207         debugfs_remove(attr->dentries.verbose_file);
 208         attr->dentries.verbose_file = NULL;
 209
 210         debugfs_remove(attr->dentries.task_filter_file);
 211         attr->dentries.task_filter_file = NULL;
 212
 213 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 214
 215         debugfs_remove(attr->dentries.stacktrace_depth_file);
 216         attr->dentries.stacktrace_depth_file = NULL;
 217
 218         debugfs_remove(attr->dentries.require_start_file);
 219         attr->dentries.require_start_file = NULL;
 220
 221         debugfs_remove(attr->dentries.require_end_file);
 222         attr->dentries.require_end_file = NULL;
 223
 224         debugfs_remove(attr->dentries.reject_start_file);
 225         attr->dentries.reject_start_file = NULL;
 226
 227         debugfs_remove(attr->dentries.reject_end_file);
 228         attr->dentries.reject_end_file = NULL;
 229
 230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 231
 232         if (attr->dentries.dir)
 233                 WARN_ON(!simple_empty(attr->dentries.dir));
 234
 235         debugfs_remove(attr->dentries.dir);
 236         attr->dentries.dir = NULL;
 237 }
 238
 239 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 240 {
 241         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 242         struct dentry *dir;
 243
 244         memset(&attr->dentries, 0, sizeof(attr->dentries));
 245
 246         dir = debugfs_create_dir(name, NULL);
 247         if (!dir)
 248                 goto fail;
 249         attr->dentries.dir = dir;
 250
 251         attr->dentries.probability_file =
 252                 debugfs_create_ul("probability", mode, dir, &attr->probability);
 253
 254         attr->dentries.interval_file =
 255                 debugfs_create_ul("interval", mode, dir, &attr->interval);
 256
 257         attr->dentries.times_file =
 258                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
 259
 260         attr->dentries.space_file =
 261                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
 262
 263         attr->dentries.verbose_file =
 264                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 265
 266         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 267                                                 mode, dir, &attr->task_filter);
 268
 269         if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
 270             !attr->dentries.times_file || !attr->dentries.space_file ||
 271             !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
 272                 goto fail;
 273
 274 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 275
 276         attr->dentries.stacktrace_depth_file =
 277                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 278                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
 279
 280         attr->dentries.require_start_file =
 281                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 282
 283         attr->dentries.require_end_file =
 284                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 285
 286         attr->dentries.reject_start_file =
 287                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 288
 289         attr->dentries.reject_end_file =
 290                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 291
 292         if (!attr->dentries.stacktrace_depth_file ||
 293             !attr->dentries.require_start_file ||
 294             !attr->dentries.require_end_file ||
 295             !attr->dentries.reject_start_file ||
 296             !attr->dentries.reject_end_file)
 297                 goto fail;
 298
 299 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 300
 301         return 0;
 302 fail:
 303         cleanup_fault_attr_dentries(attr);
 304         return -ENOMEM;
 305 }
 306
 307 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */