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
  76         save_stack_trace(&trace);
  77         for (n = 0; n < trace.nr_entries; n++) {
  78                 if (attr->reject_start <= entries[n] &&
  79                                entries[n] < attr->reject_end)
  80                         return false;
  81                 if (attr->require_start <= entries[n] &&
  82                                entries[n] < attr->require_end)
  83                         found = true;
  84         }
  85         return found;
  86 }
  87
  88 #else
  89
  90 static inline bool fail_stacktrace(struct fault_attr *attr)
  91 {
  92         return true;
  93 }
  94
  95 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
  96
  97 /*
  98  * This code is stolen from failmalloc-1.0
  99  * http://www.nongnu.org/failmalloc/
 100  */
 101
 102 bool should_fail(struct fault_attr *attr, ssize_t size)
 103 {
 104         if (attr->task_filter && !fail_task(attr, current))
 105                 return false;
 106
 107         if (atomic_read(&attr->times) == 0)
 108                 return false;
 109
 110         if (atomic_read(&attr->space) > size) {
 111                 atomic_sub(size, &attr->space);
 112                 return false;
 113         }
 114
 115         if (attr->interval > 1) {
 116                 attr->count++;
 117                 if (attr->count % attr->interval)
 118                         return false;
 119         }
 120
 121         if (attr->probability <= random32() % 100)
 122                 return false;
 123
 124         if (!fail_stacktrace(attr))
 125                 return false;
 126
 127         fail_dump(attr);
 128
 129         if (atomic_read(&attr->times) != -1)
 130                 atomic_dec_not_zero(&attr->times);
 131
 132         return true;
 133 }
 134
 135 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 136
 137 static void debugfs_ul_set(void *data, u64 val)
 138 {
 139         *(unsigned long *)data = val;
 140 }
 141
 142 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
 143 {
 144         *(unsigned long *)data =
 145                 val < MAX_STACK_TRACE_DEPTH ?
 146                 val : MAX_STACK_TRACE_DEPTH;
 147 }
 148
 149 static u64 debugfs_ul_get(void *data)
 150 {
 151         return *(unsigned long *)data;
 152 }
 153
 154 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 155
 156 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 157                                 struct dentry *parent, unsigned long *value)
 158 {
 159         return debugfs_create_file(name, mode, parent, value, &fops_ul);
 160 }
 161
 162 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
 163                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
 164
 165 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 166         const char *name, mode_t mode,
 167         struct dentry *parent, unsigned long *value)
 168 {
 169         return debugfs_create_file(name, mode, parent, value,
 170                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
 171 }
 172
 173 static void debugfs_atomic_t_set(void *data, u64 val)
 174 {
 175         atomic_set((atomic_t *)data, val);
 176 }
 177
 178 static u64 debugfs_atomic_t_get(void *data)
 179 {
 180         return atomic_read((atomic_t *)data);
 181 }
 182
 183 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
 184                         debugfs_atomic_t_set, "%lld\n");
 185
 186 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 187                                 struct dentry *parent, atomic_t *value)
 188 {
 189         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 190 }
 191
 192 void cleanup_fault_attr_dentries(struct fault_attr *attr)
 193 {
 194         debugfs_remove(attr->dentries.probability_file);
 195         attr->dentries.probability_file = NULL;
 196
 197         debugfs_remove(attr->dentries.interval_file);
 198         attr->dentries.interval_file = NULL;
 199
 200         debugfs_remove(attr->dentries.times_file);
 201         attr->dentries.times_file = NULL;
 202
 203         debugfs_remove(attr->dentries.space_file);
 204         attr->dentries.space_file = NULL;
 205
 206         debugfs_remove(attr->dentries.verbose_file);
 207         attr->dentries.verbose_file = NULL;
 208
 209         debugfs_remove(attr->dentries.task_filter_file);
 210         attr->dentries.task_filter_file = NULL;
 211
 212 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 213
 214         debugfs_remove(attr->dentries.stacktrace_depth_file);
 215         attr->dentries.stacktrace_depth_file = NULL;
 216
 217         debugfs_remove(attr->dentries.require_start_file);
 218         attr->dentries.require_start_file = NULL;
 219
 220         debugfs_remove(attr->dentries.require_end_file);
 221         attr->dentries.require_end_file = NULL;
 222
 223         debugfs_remove(attr->dentries.reject_start_file);
 224         attr->dentries.reject_start_file = NULL;
 225
 226         debugfs_remove(attr->dentries.reject_end_file);
 227         attr->dentries.reject_end_file = NULL;
 228
 229 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 230
 231         if (attr->dentries.dir)
 232                 WARN_ON(!simple_empty(attr->dentries.dir));
 233
 234         debugfs_remove(attr->dentries.dir);
 235         attr->dentries.dir = NULL;
 236 }
 237
 238 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 239 {
 240         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 241         struct dentry *dir;
 242
 243         memset(&attr->dentries, 0, sizeof(attr->dentries));
 244
 245         dir = debugfs_create_dir(name, NULL);
 246         if (!dir)
 247                 goto fail;
 248         attr->dentries.dir = dir;
 249
 250         attr->dentries.probability_file =
 251                 debugfs_create_ul("probability", mode, dir, &attr->probability);
 252
 253         attr->dentries.interval_file =
 254                 debugfs_create_ul("interval", mode, dir, &attr->interval);
 255
 256         attr->dentries.times_file =
 257                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
 258
 259         attr->dentries.space_file =
 260                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
 261
 262         attr->dentries.verbose_file =
 263                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 264
 265         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 266                                                 mode, dir, &attr->task_filter);
 267
 268         if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
 269             !attr->dentries.times_file || !attr->dentries.space_file ||
 270             !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
 271                 goto fail;
 272
 273 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 274
 275         attr->dentries.stacktrace_depth_file =
 276                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 277                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
 278
 279         attr->dentries.require_start_file =
 280                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 281
 282         attr->dentries.require_end_file =
 283                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 284
 285         attr->dentries.reject_start_file =
 286                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 287
 288         attr->dentries.reject_end_file =
 289                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 290
 291         if (!attr->dentries.stacktrace_depth_file ||
 292             !attr->dentries.require_start_file ||
 293             !attr->dentries.require_end_file ||
 294             !attr->dentries.reject_start_file ||
 295             !attr->dentries.reject_end_file)
 296                 goto fail;
 297
 298 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 299
 300         return 0;
 301 fail:
 302         cleanup_fault_attr_dentries(attr);
 303         return -ENOMEM;
 304 }
 305
 306 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */