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TOMOYO Linux Cross Reference
Linux/lib/fault-inject.c

Version: ~ [ linux-5.12-rc7 ] ~ [ linux-5.11.13 ] ~ [ linux-5.10.29 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.111 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.186 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.230 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.266 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.266 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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, &times) < 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         if (in_task()) {
111                 unsigned int fail_nth = READ_ONCE(current->fail_nth);
112 
113                 if (fail_nth) {
114                         if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
115                                 goto fail;
116 
117                         return false;
118                 }
119         }
120 
121         /* No need to check any other properties if the probability is 0 */
122         if (attr->probability == 0)
123                 return false;
124 
125         if (attr->task_filter && !fail_task(attr, current))
126                 return false;
127 
128         if (atomic_read(&attr->times) == 0)
129                 return false;
130 
131         if (atomic_read(&attr->space) > size) {
132                 atomic_sub(size, &attr->space);
133                 return false;
134         }
135 
136         if (attr->interval > 1) {
137                 attr->count++;
138                 if (attr->count % attr->interval)
139                         return false;
140         }
141 
142         if (attr->probability <= prandom_u32() % 100)
143                 return false;
144 
145         if (!fail_stacktrace(attr))
146                 return false;
147 
148 fail:
149         fail_dump(attr);
150 
151         if (atomic_read(&attr->times) != -1)
152                 atomic_dec_not_zero(&attr->times);
153 
154         return true;
155 }
156 EXPORT_SYMBOL_GPL(should_fail);
157 
158 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
159 
160 static int debugfs_ul_set(void *data, u64 val)
161 {
162         *(unsigned long *)data = val;
163         return 0;
164 }
165 
166 static int debugfs_ul_get(void *data, u64 *val)
167 {
168         *val = *(unsigned long *)data;
169         return 0;
170 }
171 
172 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
173 
174 static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
175                                 struct dentry *parent, unsigned long *value)
176 {
177         return debugfs_create_file(name, mode, parent, value, &fops_ul);
178 }
179 
180 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
181 
182 static int debugfs_stacktrace_depth_set(void *data, u64 val)
183 {
184         *(unsigned long *)data =
185                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
186 
187         return 0;
188 }
189 
190 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
191                         debugfs_stacktrace_depth_set, "%llu\n");
192 
193 static struct dentry *debugfs_create_stacktrace_depth(
194         const char *name, umode_t mode,
195         struct dentry *parent, unsigned long *value)
196 {
197         return debugfs_create_file(name, mode, parent, value,
198                                    &fops_stacktrace_depth);
199 }
200 
201 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
202 
203 struct dentry *fault_create_debugfs_attr(const char *name,
204                         struct dentry *parent, struct fault_attr *attr)
205 {
206         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
207         struct dentry *dir;
208 
209         dir = debugfs_create_dir(name, parent);
210         if (!dir)
211                 return ERR_PTR(-ENOMEM);
212 
213         if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
214                 goto fail;
215         if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
216                 goto fail;
217         if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
218                 goto fail;
219         if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
220                 goto fail;
221         if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
222                 goto fail;
223         if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
224                                 &attr->ratelimit_state.interval))
225                 goto fail;
226         if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
227                                 &attr->ratelimit_state.burst))
228                 goto fail;
229         if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
230                 goto fail;
231 
232 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
233 
234         if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
235                                 &attr->stacktrace_depth))
236                 goto fail;
237         if (!debugfs_create_ul("require-start", mode, dir,
238                                 &attr->require_start))
239                 goto fail;
240         if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
241                 goto fail;
242         if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
243                 goto fail;
244         if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
245                 goto fail;
246 
247 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
248 
249         attr->dname = dget(dir);
250         return dir;
251 fail:
252         debugfs_remove_recursive(dir);
253 
254         return ERR_PTR(-ENOMEM);
255 }
256 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
257 
258 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
259 

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