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 #if defined(CONFIG_STACKTRACE)
  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         static bool firsttime = true;
  94
  95         if (firsttime) {
  96                 printk(KERN_WARNING
  97                 "This architecture does not implement save_stack_trace()\n");
  98                 firsttime = false;
  99         }
 100         return false;
 101 }
 102
 103 #endif
 104
 105 /*
 106  * This code is stolen from failmalloc-1.0
 107  * http://www.nongnu.org/failmalloc/
 108  */
 109
 110 bool should_fail(struct fault_attr *attr, ssize_t size)
 111 {
 112         if (attr->task_filter && !fail_task(attr, current))
 113                 return false;
 114
 115         if (atomic_read(&attr->times) == 0)
 116                 return false;
 117
 118         if (atomic_read(&attr->space) > size) {
 119                 atomic_sub(size, &attr->space);
 120                 return false;
 121         }
 122
 123         if (attr->interval > 1) {
 124                 attr->count++;
 125                 if (attr->count % attr->interval)
 126                         return false;
 127         }
 128
 129         if (attr->probability <= random32() % 100)
 130                 return false;
 131
 132         if (!fail_stacktrace(attr))
 133                 return false;
 134
 135         fail_dump(attr);
 136
 137         if (atomic_read(&attr->times) != -1)
 138                 atomic_dec_not_zero(&attr->times);
 139
 140         return true;
 141 }
 142
 143 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 144
 145 static void debugfs_ul_set(void *data, u64 val)
 146 {
 147         *(unsigned long *)data = val;
 148 }
 149
 150 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
 151 {
 152         *(unsigned long *)data =
 153                 val < MAX_STACK_TRACE_DEPTH ?
 154                 val : MAX_STACK_TRACE_DEPTH;
 155 }
 156
 157 static u64 debugfs_ul_get(void *data)
 158 {
 159         return *(unsigned long *)data;
 160 }
 161
 162 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 163
 164 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 165                                 struct dentry *parent, unsigned long *value)
 166 {
 167         return debugfs_create_file(name, mode, parent, value, &fops_ul);
 168 }
 169
 170 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
 171                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
 172
 173 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 174         const char *name, mode_t mode,
 175         struct dentry *parent, unsigned long *value)
 176 {
 177         return debugfs_create_file(name, mode, parent, value,
 178                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
 179 }
 180
 181 static void debugfs_atomic_t_set(void *data, u64 val)
 182 {
 183         atomic_set((atomic_t *)data, val);
 184 }
 185
 186 static u64 debugfs_atomic_t_get(void *data)
 187 {
 188         return atomic_read((atomic_t *)data);
 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         debugfs_remove(attr->dentries.stacktrace_depth_file);
 221         attr->dentries.stacktrace_depth_file = NULL;
 222
 223         debugfs_remove(attr->dentries.require_start_file);
 224         attr->dentries.require_start_file = NULL;
 225
 226         debugfs_remove(attr->dentries.require_end_file);
 227         attr->dentries.require_end_file = NULL;
 228
 229         debugfs_remove(attr->dentries.reject_start_file);
 230         attr->dentries.reject_start_file = NULL;
 231
 232         debugfs_remove(attr->dentries.reject_end_file);
 233         attr->dentries.reject_end_file = NULL;
 234
 235         if (attr->dentries.dir)
 236                 WARN_ON(!simple_empty(attr->dentries.dir));
 237
 238         debugfs_remove(attr->dentries.dir);
 239         attr->dentries.dir = NULL;
 240 }
 241
 242 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 243 {
 244         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 245         struct dentry *dir;
 246
 247         memset(&attr->dentries, 0, sizeof(attr->dentries));
 248
 249         dir = debugfs_create_dir(name, NULL);
 250         if (!dir)
 251                 goto fail;
 252         attr->dentries.dir = dir;
 253
 254         attr->dentries.probability_file =
 255                 debugfs_create_ul("probability", mode, dir, &attr->probability);
 256
 257         attr->dentries.interval_file =
 258                 debugfs_create_ul("interval", mode, dir, &attr->interval);
 259
 260         attr->dentries.times_file =
 261                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
 262
 263         attr->dentries.space_file =
 264                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
 265
 266         attr->dentries.verbose_file =
 267                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 268
 269         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 270                                                 mode, dir, &attr->task_filter);
 271
 272         attr->dentries.stacktrace_depth_file =
 273                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 274                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
 275
 276         attr->dentries.require_start_file =
 277                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 278
 279         attr->dentries.require_end_file =
 280                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 281
 282         attr->dentries.reject_start_file =
 283                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 284
 285         attr->dentries.reject_end_file =
 286                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 287
 288
 289         if (!attr->dentries.probability_file || !attr->dentries.interval_file
 290             || !attr->dentries.times_file || !attr->dentries.space_file
 291             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
 292             || !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             )
 298                 goto fail;
 299
 300         return 0;
 301 fail:
 302         cleanup_fault_attr_dentries(attr);
 303         return -ENOMEM;
 304 }
 305
 306 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */