linux/lib/fault-inject.c
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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/*
  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 */
  18int __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
  41static 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
  51static 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
  60static 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
  90static 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
 102bool 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
 137static int debugfs_ul_set(void *data, u64 val)
 138{
 139        *(unsigned long *)data = val;
 140        return 0;
 141}
 142
 143#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 144static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
 145{
 146        *(unsigned long *)data =
 147                val < MAX_STACK_TRACE_DEPTH ?
 148                val : MAX_STACK_TRACE_DEPTH;
 149        return 0;
 150}
 151#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 152
 153static int debugfs_ul_get(void *data, u64 *val)
 154{
 155        *val = *(unsigned long *)data;
 156        return 0;
 157}
 158
 159DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 160
 161static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 162                                struct dentry *parent, unsigned long *value)
 163{
 164        return debugfs_create_file(name, mode, parent, value, &fops_ul);
 165}
 166
 167#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 168DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
 169                        debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
 170
 171static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 172        const char *name, mode_t mode,
 173        struct dentry *parent, unsigned long *value)
 174{
 175        return debugfs_create_file(name, mode, parent, value,
 176                                   &fops_ul_MAX_STACK_TRACE_DEPTH);
 177}
 178#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 179
 180static int debugfs_atomic_t_set(void *data, u64 val)
 181{
 182        atomic_set((atomic_t *)data, val);
 183        return 0;
 184}
 185
 186static int debugfs_atomic_t_get(void *data, u64 *val)
 187{
 188        *val = atomic_read((atomic_t *)data);
 189        return 0;
 190}
 191
 192DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
 193                        debugfs_atomic_t_set, "%lld\n");
 194
 195static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 196                                struct dentry *parent, atomic_t *value)
 197{
 198        return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 199}
 200
 201void cleanup_fault_attr_dentries(struct fault_attr *attr)
 202{
 203        debugfs_remove(attr->dentries.probability_file);
 204        attr->dentries.probability_file = NULL;
 205
 206        debugfs_remove(attr->dentries.interval_file);
 207        attr->dentries.interval_file = NULL;
 208
 209        debugfs_remove(attr->dentries.times_file);
 210        attr->dentries.times_file = NULL;
 211
 212        debugfs_remove(attr->dentries.space_file);
 213        attr->dentries.space_file = NULL;
 214
 215        debugfs_remove(attr->dentries.verbose_file);
 216        attr->dentries.verbose_file = NULL;
 217
 218        debugfs_remove(attr->dentries.task_filter_file);
 219        attr->dentries.task_filter_file = NULL;
 220
 221#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 222
 223        debugfs_remove(attr->dentries.stacktrace_depth_file);
 224        attr->dentries.stacktrace_depth_file = NULL;
 225
 226        debugfs_remove(attr->dentries.require_start_file);
 227        attr->dentries.require_start_file = NULL;
 228
 229        debugfs_remove(attr->dentries.require_end_file);
 230        attr->dentries.require_end_file = NULL;
 231
 232        debugfs_remove(attr->dentries.reject_start_file);
 233        attr->dentries.reject_start_file = NULL;
 234
 235        debugfs_remove(attr->dentries.reject_end_file);
 236        attr->dentries.reject_end_file = NULL;
 237
 238#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 239
 240        if (attr->dentries.dir)
 241                WARN_ON(!simple_empty(attr->dentries.dir));
 242
 243        debugfs_remove(attr->dentries.dir);
 244        attr->dentries.dir = NULL;
 245}
 246
 247int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 248{
 249        mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 250        struct dentry *dir;
 251
 252        memset(&attr->dentries, 0, sizeof(attr->dentries));
 253
 254        dir = debugfs_create_dir(name, NULL);
 255        if (!dir)
 256                goto fail;
 257        attr->dentries.dir = dir;
 258
 259        attr->dentries.probability_file =
 260                debugfs_create_ul("probability", mode, dir, &attr->probability);
 261
 262        attr->dentries.interval_file =
 263                debugfs_create_ul("interval", mode, dir, &attr->interval);
 264
 265        attr->dentries.times_file =
 266                debugfs_create_atomic_t("times", mode, dir, &attr->times);
 267
 268        attr->dentries.space_file =
 269                debugfs_create_atomic_t("space", mode, dir, &attr->space);
 270
 271        attr->dentries.verbose_file =
 272                debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 273
 274        attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 275                                                mode, dir, &attr->task_filter);
 276
 277        if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
 278            !attr->dentries.times_file || !attr->dentries.space_file ||
 279            !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
 280                goto fail;
 281
 282#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 283
 284        attr->dentries.stacktrace_depth_file =
 285                debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 286                        "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
 287
 288        attr->dentries.require_start_file =
 289                debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 290
 291        attr->dentries.require_end_file =
 292                debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 293
 294        attr->dentries.reject_start_file =
 295                debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 296
 297        attr->dentries.reject_end_file =
 298                debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 299
 300        if (!attr->dentries.stacktrace_depth_file ||
 301            !attr->dentries.require_start_file ||
 302            !attr->dentries.require_end_file ||
 303            !attr->dentries.reject_start_file ||
 304            !attr->dentries.reject_end_file)
 305                goto fail;
 306
 307#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 308
 309        return 0;
 310fail:
 311        cleanup_fault_attr_dentries(attr);
 312        return -ENOMEM;
 313}
 314
 315#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
 316
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