summaryrefslogtreecommitdiff
path: root/lib/fault-inject.c
blob: 52eb6ba29698446a39d80bed6a0e2bf4297234b5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/debugfs.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/stacktrace.h>
#include <linux/fault-inject.h>

/*
 * setup_fault_attr() is a helper function for various __setup handlers, so it
 * returns 0 on error, because that is what __setup handlers do.
 */
int setup_fault_attr(struct fault_attr *attr, char *str)
{
	unsigned long probability;
	unsigned long interval;
	int times;
	int space;

	/* "<interval>,<probability>,<space>,<times>" */
	if (sscanf(str, "%lu,%lu,%d,%d",
			&interval, &probability, &space, &times) < 4) {
		printk(KERN_WARNING
			"FAULT_INJECTION: failed to parse arguments\n");
		return 0;
	}

	attr->probability = probability;
	attr->interval = interval;
	atomic_set(&attr->times, times);
	atomic_set(&attr->space, space);

	return 1;
}
EXPORT_SYMBOL_GPL(setup_fault_attr);

static void fail_dump(struct fault_attr *attr)
{
	if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
		       "name %pd, interval %lu, probability %lu, "
		       "space %d, times %d\n", attr->dname,
		       attr->interval, attr->probability,
		       atomic_read(&attr->space),
		       atomic_read(&attr->times));
		if (attr->verbose > 1)
			dump_stack();
	}
}

#define atomic_dec_not_zero(v)		atomic_add_unless((v), -1, 0)

static bool fail_task(struct fault_attr *attr, struct task_struct *task)
{
	return in_task() && task->make_it_fail;
}

#define MAX_STACK_TRACE_DEPTH 32

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

static bool fail_stacktrace(struct fault_attr *attr)
{
	int depth = attr->stacktrace_depth;
	unsigned long entries[MAX_STACK_TRACE_DEPTH];
	int n, nr_entries;
	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);

	if (depth == 0 || (found && !attr->reject_start && !attr->reject_end))
		return found;

	nr_entries = stack_trace_save(entries, depth, 1);
	for (n = 0; n < nr_entries; n++) {
		if (attr->reject_start <= entries[n] &&
			       entries[n] < attr->reject_end)
			return false;
		if (attr->require_start <= entries[n] &&
			       entries[n] < attr->require_end)
			found = true;
	}
	return found;
}

#else

static inline bool fail_stacktrace(struct fault_attr *attr)
{
	return true;
}

#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

/*
 * This code is stolen from failmalloc-1.0
 * http://www.nongnu.org/failmalloc/
 */

bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
{
	bool stack_checked = false;

	if (in_task()) {
		unsigned int fail_nth = READ_ONCE(current->fail_nth);

		if (fail_nth) {
			if (!fail_stacktrace(attr))
				return false;

			stack_checked = true;
			fail_nth--;
			WRITE_ONCE(current->fail_nth, fail_nth);
			if (!fail_nth)
				goto fail;

			return false;
		}
	}

	/* No need to check any other properties if the probability is 0 */
	if (attr->probability == 0)
		return false;

	if (attr->task_filter && !fail_task(attr, current))
		return false;

	if (atomic_read(&attr->times) == 0)
		return false;

	if (!stack_checked && !fail_stacktrace(attr))
		return false;

	if (atomic_read(&attr->space) > size) {
		atomic_sub(size, &attr->space);
		return false;
	}

	if (attr->interval > 1) {
		attr->count++;
		if (attr->count % attr->interval)
			return false;
	}

	if (attr->probability <= get_random_u32_below(100))
		return false;

fail:
	if (!(flags & FAULT_NOWARN))
		fail_dump(attr);

	if (atomic_read(&attr->times) != -1)
		atomic_dec_not_zero(&attr->times);

	return true;
}

bool should_fail(struct fault_attr *attr, ssize_t size)
{
	return should_fail_ex(attr, size, 0);
}
EXPORT_SYMBOL_GPL(should_fail);

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

static int debugfs_ul_set(void *data, u64 val)
{
	*(unsigned long *)data = val;
	return 0;
}

static int debugfs_ul_get(void *data, u64 *val)
{
	*val = *(unsigned long *)data;
	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");

static void debugfs_create_ul(const char *name, umode_t mode,
			      struct dentry *parent, unsigned long *value)
{
	debugfs_create_file(name, mode, parent, value, &fops_ul);
}

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

static int debugfs_stacktrace_depth_set(void *data, u64 val)
{
	*(unsigned long *)data =
		min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);

	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
			debugfs_stacktrace_depth_set, "%llu\n");

static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
					    struct dentry *parent,
					    unsigned long *value)
{
	debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
}

#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

struct dentry *fault_create_debugfs_attr(const char *name,
			struct dentry *parent, struct fault_attr *attr)
{
	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
	struct dentry *dir;

	dir = debugfs_create_dir(name, parent);
	if (IS_ERR(dir))
		return dir;

	debugfs_create_ul("probability", mode, dir, &attr->probability);
	debugfs_create_ul("interval", mode, dir, &attr->interval);
	debugfs_create_atomic_t("times", mode, dir, &attr->times);
	debugfs_create_atomic_t("space", mode, dir, &attr->space);
	debugfs_create_ul("verbose", mode, dir, &attr->verbose);
	debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
			   &attr->ratelimit_state.interval);
	debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
			   &attr->ratelimit_state.burst);
	debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
	debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
					&attr->stacktrace_depth);
	debugfs_create_xul("require-start", mode, dir, &attr->require_start);
	debugfs_create_xul("require-end", mode, dir, &attr->require_end);
	debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
	debugfs_create_xul("reject-end", mode, dir, &attr->reject_end);
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

	attr->dname = dget(dir);
	return dir;
}
EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

#ifdef CONFIG_FAULT_INJECTION_CONFIGFS

/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */

static ssize_t fault_uint_attr_show(unsigned int val, char *page)
{
	return snprintf(page, PAGE_SIZE, "%u\n", val);
}

static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
{
	return snprintf(page, PAGE_SIZE, "%lu\n", val);
}

static ssize_t fault_bool_attr_show(bool val, char *page)
{
	return snprintf(page, PAGE_SIZE, "%u\n", val);
}

static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page)
{
	return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val));
}

static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count)
{
	unsigned int tmp;
	int result;

	result = kstrtouint(page, 0, &tmp);
	if (result < 0)
		return result;

	*val = tmp;
	return count;
}

static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count)
{
	int result;
	unsigned long tmp;

	result = kstrtoul(page, 0, &tmp);
	if (result < 0)
		return result;

	*val = tmp;
	return count;
}

static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count)
{
	bool tmp;
	int result;

	result = kstrtobool(page, &tmp);
	if (result < 0)
		return result;

	*val = tmp;
	return count;
}

static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count)
{
	int tmp;
	int result;

	result = kstrtoint(page, 0, &tmp);
	if (result < 0)
		return result;

	atomic_set(val, tmp);
	return count;
}

#define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name)	\
static struct configfs_attribute _pfx##attr_##_name = {	\
	.ca_name	= _attr_name,			\
	.ca_mode	= 0644,				\
	.ca_owner	= THIS_MODULE,			\
	.show		= _pfx##_name##_show,		\
	.store		= _pfx##_name##_store,		\
}

static struct fault_config *to_fault_config(struct config_item *item)
{
	return container_of(to_config_group(item), struct fault_config, group);
}

#define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE)				\
static ssize_t fault_##NAME##_show(struct config_item *item, char *page)			\
{												\
	return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page);		\
}												\
static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count)	\
{												\
	struct fault_config *config = to_fault_config(item);					\
	return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count);			\
}												\
CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME)

#define FAULT_CONFIGFS_ATTR(NAME, TYPE)	\
	FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE)

FAULT_CONFIGFS_ATTR(probability, ulong);
FAULT_CONFIGFS_ATTR(interval, ulong);
FAULT_CONFIGFS_ATTR(times, atomic_t);
FAULT_CONFIGFS_ATTR(space, atomic_t);
FAULT_CONFIGFS_ATTR(verbose, ulong);
FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
		ratelimit_state.interval, uint);
FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
		ratelimit_state.burst, uint);
FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page)
{
	return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page);
}

static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page,
		size_t count)
{
	int result;
	unsigned long tmp;

	result = kstrtoul(page, 0, &tmp);
	if (result < 0)
		return result;

	to_fault_config(item)->attr.stacktrace_depth =
		min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH);

	return count;
}

CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");

static ssize_t fault_xul_attr_show(unsigned long val, char *page)
{
	return snprintf(page, PAGE_SIZE,
			sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val);
}

static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count)
{
	return fault_ulong_attr_store(val, page, count);
}

FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);

#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

static struct configfs_attribute *fault_config_attrs[] = {
	&fault_attr_probability,
	&fault_attr_interval,
	&fault_attr_times,
	&fault_attr_space,
	&fault_attr_verbose,
	&fault_attr_ratelimit_interval,
	&fault_attr_ratelimit_burst,
	&fault_attr_task_filter,
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
	&fault_attr_stacktrace_depth,
	&fault_attr_require_start,
	&fault_attr_require_end,
	&fault_attr_reject_start,
	&fault_attr_reject_end,
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
	NULL,
};

static const struct config_item_type fault_config_type = {
	.ct_attrs	= fault_config_attrs,
	.ct_owner	= THIS_MODULE,
};

void fault_config_init(struct fault_config *config, const char *name)
{
	config_group_init_type_name(&config->group, name, &fault_config_type);
}
EXPORT_SYMBOL_GPL(fault_config_init);

#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */