1 #include <linux/kernel.h> 2 #include <linux/init.h> 3 #include <linux/random.h> 4 #include <linux/sched.h> 5 #include <linux/stat.h> 6 #include <linux/types.h> 7 #include <linux/fs.h> 8 #include <linux/export.h> 9 #include <linux/interrupt.h> 10 #include <linux/stacktrace.h> 11 #include <linux/fault-inject.h> 12 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 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 24 /* "<interval>,<probability>,<space>,<times>" */ 25 if (sscanf(str, "%lu,%lu,%d,%d", 26 &interval, &probability, &space, ×) < 4) { 27 printk(KERN_WARNING 28 "FAULT_INJECTION: failed to parse arguments\n"); 29 return 0; 30 } 31 32 attr->probability = probability; 33 attr->interval = interval; 34 atomic_set(&attr->times, times); 35 atomic_set(&attr->space, space); 36 37 return 1; 38 } 39 EXPORT_SYMBOL_GPL(setup_fault_attr); 40 41 static void fail_dump(struct fault_attr *attr) 42 { 43 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { 44 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" 45 "name %pd, interval %lu, probability %lu, " 46 "space %d, times %d\n", attr->dname, 47 attr->interval, attr->probability, 48 atomic_read(&attr->space), 49 atomic_read(&attr->times)); 50 if (attr->verbose > 1) 51 dump_stack(); 52 } 53 } 54 55 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 56 57 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 58 { 59 return in_task() && task->make_it_fail; 60 } 61 62 #define MAX_STACK_TRACE_DEPTH 32 63 64 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 65 66 static bool fail_stacktrace(struct fault_attr *attr) 67 { 68 struct stack_trace trace; 69 int depth = attr->stacktrace_depth; 70 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 71 int n; 72 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 73 74 if (depth == 0) 75 return found; 76 77 trace.nr_entries = 0; 78 trace.entries = entries; 79 trace.max_entries = depth; 80 trace.skip = 1; 81 82 save_stack_trace(&trace); 83 for (n = 0; n < trace.nr_entries; n++) { 84 if (attr->reject_start <= entries[n] && 85 entries[n] < attr->reject_end) 86 return false; 87 if (attr->require_start <= entries[n] && 88 entries[n] < attr->require_end) 89 found = true; 90 } 91 return found; 92 } 93 94 #else 95 96 static inline bool fail_stacktrace(struct fault_attr *attr) 97 { 98 return true; 99 } 100 101 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 102 103 /* 104 * This code is stolen from failmalloc-1.0 105 * http://www.nongnu.org/failmalloc/ 106 */ 107 108 bool should_fail(struct fault_attr *attr, ssize_t size) 109 { 110 /* No need to check any other properties if the probability is 0 */ 111 if (attr->probability == 0) 112 return false; 113 114 if (attr->task_filter && !fail_task(attr, current)) 115 return false; 116 117 if (atomic_read(&attr->times) == 0) 118 return false; 119 120 if (atomic_read(&attr->space) > size) { 121 atomic_sub(size, &attr->space); 122 return false; 123 } 124 125 if (attr->interval > 1) { 126 attr->count++; 127 if (attr->count % attr->interval) 128 return false; 129 } 130 131 if (attr->probability <= prandom_u32() % 100) 132 return false; 133 134 if (!fail_stacktrace(attr)) 135 return false; 136 137 fail_dump(attr); 138 139 if (atomic_read(&attr->times) != -1) 140 atomic_dec_not_zero(&attr->times); 141 142 return true; 143 } 144 EXPORT_SYMBOL_GPL(should_fail); 145 146 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 147 148 static int debugfs_ul_set(void *data, u64 val) 149 { 150 *(unsigned long *)data = val; 151 return 0; 152 } 153 154 static int debugfs_ul_get(void *data, u64 *val) 155 { 156 *val = *(unsigned long *)data; 157 return 0; 158 } 159 160 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 161 162 static struct dentry *debugfs_create_ul(const char *name, umode_t mode, 163 struct dentry *parent, unsigned long *value) 164 { 165 return debugfs_create_file(name, mode, parent, value, &fops_ul); 166 } 167 168 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 169 170 static int debugfs_stacktrace_depth_set(void *data, u64 val) 171 { 172 *(unsigned long *)data = 173 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 174 175 return 0; 176 } 177 178 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 179 debugfs_stacktrace_depth_set, "%llu\n"); 180 181 static struct dentry *debugfs_create_stacktrace_depth( 182 const char *name, umode_t mode, 183 struct dentry *parent, unsigned long *value) 184 { 185 return debugfs_create_file(name, mode, parent, value, 186 &fops_stacktrace_depth); 187 } 188 189 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 190 191 struct dentry *fault_create_debugfs_attr(const char *name, 192 struct dentry *parent, struct fault_attr *attr) 193 { 194 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 195 struct dentry *dir; 196 197 dir = debugfs_create_dir(name, parent); 198 if (!dir) 199 return ERR_PTR(-ENOMEM); 200 201 if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) 202 goto fail; 203 if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) 204 goto fail; 205 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) 206 goto fail; 207 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) 208 goto fail; 209 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) 210 goto fail; 211 if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, 212 &attr->ratelimit_state.interval)) 213 goto fail; 214 if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir, 215 &attr->ratelimit_state.burst)) 216 goto fail; 217 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) 218 goto fail; 219 220 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 221 222 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 223 &attr->stacktrace_depth)) 224 goto fail; 225 if (!debugfs_create_ul("require-start", mode, dir, 226 &attr->require_start)) 227 goto fail; 228 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) 229 goto fail; 230 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) 231 goto fail; 232 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) 233 goto fail; 234 235 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 236 237 attr->dname = dget(dir); 238 return dir; 239 fail: 240 debugfs_remove_recursive(dir); 241 242 return ERR_PTR(-ENOMEM); 243 } 244 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 245 246 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 247