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) 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 /* No need to check any other properties if the probability is 0 */ 105 if (attr->probability == 0) 106 return false; 107 108 if (attr->task_filter && !fail_task(attr, current)) 109 return false; 110 111 if (atomic_read(&attr->times) == 0) 112 return false; 113 114 if (atomic_read(&attr->space) > size) { 115 atomic_sub(size, &attr->space); 116 return false; 117 } 118 119 if (attr->interval > 1) { 120 attr->count++; 121 if (attr->count % attr->interval) 122 return false; 123 } 124 125 if (attr->probability <= prandom_u32() % 100) 126 return false; 127 128 if (!fail_stacktrace(attr)) 129 return false; 130 131 fail_dump(attr); 132 133 if (atomic_read(&attr->times) != -1) 134 atomic_dec_not_zero(&attr->times); 135 136 return true; 137 } 138 EXPORT_SYMBOL_GPL(should_fail); 139 140 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 141 142 static int debugfs_ul_set(void *data, u64 val) 143 { 144 *(unsigned long *)data = val; 145 return 0; 146 } 147 148 static int debugfs_ul_get(void *data, u64 *val) 149 { 150 *val = *(unsigned long *)data; 151 return 0; 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, umode_t mode, 157 struct dentry *parent, unsigned long *value) 158 { 159 return debugfs_create_file(name, mode, parent, value, &fops_ul); 160 } 161 162 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 163 164 static int debugfs_stacktrace_depth_set(void *data, u64 val) 165 { 166 *(unsigned long *)data = 167 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 168 169 return 0; 170 } 171 172 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 173 debugfs_stacktrace_depth_set, "%llu\n"); 174 175 static struct dentry *debugfs_create_stacktrace_depth( 176 const char *name, umode_t mode, 177 struct dentry *parent, unsigned long *value) 178 { 179 return debugfs_create_file(name, mode, parent, value, 180 &fops_stacktrace_depth); 181 } 182 183 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 184 185 struct dentry *fault_create_debugfs_attr(const char *name, 186 struct dentry *parent, struct fault_attr *attr) 187 { 188 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 189 struct dentry *dir; 190 191 dir = debugfs_create_dir(name, parent); 192 if (!dir) 193 return ERR_PTR(-ENOMEM); 194 195 if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) 196 goto fail; 197 if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) 198 goto fail; 199 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) 200 goto fail; 201 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) 202 goto fail; 203 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) 204 goto fail; 205 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) 206 goto fail; 207 208 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 209 210 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 211 &attr->stacktrace_depth)) 212 goto fail; 213 if (!debugfs_create_ul("require-start", mode, dir, 214 &attr->require_start)) 215 goto fail; 216 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) 217 goto fail; 218 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) 219 goto fail; 220 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) 221 goto fail; 222 223 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 224 225 return dir; 226 fail: 227 debugfs_remove_recursive(dir); 228 229 return ERR_PTR(-ENOMEM); 230 } 231 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 232 233 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 234