path: root/lib/fault-inject.c (plain)
blob: 6a823a53e357bc83e84476d93cc2c155f0adfee5

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_interrupt() && 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