Root/lib/fault-inject.c

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/module.h>
9#include <linux/interrupt.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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