1
2#include <linux/kernel.h>
3#include <linux/init.h>
4#include <linux/random.h>
5#include <linux/sched.h>
6#include <linux/stat.h>
7#include <linux/types.h>
8#include <linux/fs.h>
9#include <linux/export.h>
10#include <linux/interrupt.h>
11#include <linux/stacktrace.h>
12#include <linux/fault-inject.h>
13
14
15
16
17
18int 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
26 if (sscanf(str, "%lu,%lu,%d,%d",
27 &interval, &probability, &space, ×) < 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}
40EXPORT_SYMBOL_GPL(setup_fault_attr);
41
42static void fail_dump(struct fault_attr *attr)
43{
44 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
45 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
46 "name %pd, interval %lu, probability %lu, "
47 "space %d, times %d\n", attr->dname,
48 attr->interval, attr->probability,
49 atomic_read(&attr->space),
50 atomic_read(&attr->times));
51 if (attr->verbose > 1)
52 dump_stack();
53 }
54}
55
56#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
57
58static bool fail_task(struct fault_attr *attr, struct task_struct *task)
59{
60 return in_task() && task->make_it_fail;
61}
62
63#define MAX_STACK_TRACE_DEPTH 32
64
65#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
66
67static bool fail_stacktrace(struct fault_attr *attr)
68{
69 int depth = attr->stacktrace_depth;
70 unsigned long entries[MAX_STACK_TRACE_DEPTH];
71 int n, nr_entries;
72 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
73
74 if (depth == 0)
75 return found;
76
77 nr_entries = stack_trace_save(entries, depth, 1);
78 for (n = 0; n < nr_entries; n++) {
79 if (attr->reject_start <= entries[n] &&
80 entries[n] < attr->reject_end)
81 return false;
82 if (attr->require_start <= entries[n] &&
83 entries[n] < attr->require_end)
84 found = true;
85 }
86 return found;
87}
88
89#else
90
91static inline bool fail_stacktrace(struct fault_attr *attr)
92{
93 return true;
94}
95
96#endif
97
98
99
100
101
102
103bool should_fail(struct fault_attr *attr, ssize_t size)
104{
105 if (in_task()) {
106 unsigned int fail_nth = READ_ONCE(current->fail_nth);
107
108 if (fail_nth) {
109 fail_nth--;
110 WRITE_ONCE(current->fail_nth, fail_nth);
111 if (!fail_nth)
112 goto fail;
113
114 return false;
115 }
116 }
117
118
119 if (attr->probability == 0)
120 return false;
121
122 if (attr->task_filter && !fail_task(attr, current))
123 return false;
124
125 if (atomic_read(&attr->times) == 0)
126 return false;
127
128 if (atomic_read(&attr->space) > size) {
129 atomic_sub(size, &attr->space);
130 return false;
131 }
132
133 if (attr->interval > 1) {
134 attr->count++;
135 if (attr->count % attr->interval)
136 return false;
137 }
138
139 if (attr->probability <= prandom_u32() % 100)
140 return false;
141
142 if (!fail_stacktrace(attr))
143 return false;
144
145fail:
146 fail_dump(attr);
147
148 if (atomic_read(&attr->times) != -1)
149 atomic_dec_not_zero(&attr->times);
150
151 return true;
152}
153EXPORT_SYMBOL_GPL(should_fail);
154
155#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
156
157static int debugfs_ul_set(void *data, u64 val)
158{
159 *(unsigned long *)data = val;
160 return 0;
161}
162
163static int debugfs_ul_get(void *data, u64 *val)
164{
165 *val = *(unsigned long *)data;
166 return 0;
167}
168
169DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
170
171static void debugfs_create_ul(const char *name, umode_t mode,
172 struct dentry *parent, unsigned long *value)
173{
174 debugfs_create_file(name, mode, parent, value, &fops_ul);
175}
176
177#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
178
179static int debugfs_stacktrace_depth_set(void *data, u64 val)
180{
181 *(unsigned long *)data =
182 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
183
184 return 0;
185}
186
187DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
188 debugfs_stacktrace_depth_set, "%llu\n");
189
190static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
191 struct dentry *parent,
192 unsigned long *value)
193{
194 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
195}
196
197#endif
198
199struct dentry *fault_create_debugfs_attr(const char *name,
200 struct dentry *parent, struct fault_attr *attr)
201{
202 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
203 struct dentry *dir;
204
205 dir = debugfs_create_dir(name, parent);
206 if (IS_ERR(dir))
207 return dir;
208
209 debugfs_create_ul("probability", mode, dir, &attr->probability);
210 debugfs_create_ul("interval", mode, dir, &attr->interval);
211 debugfs_create_atomic_t("times", mode, dir, &attr->times);
212 debugfs_create_atomic_t("space", mode, dir, &attr->space);
213 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
214 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
215 &attr->ratelimit_state.interval);
216 debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
217 &attr->ratelimit_state.burst);
218 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
219
220#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
222 &attr->stacktrace_depth);
223 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
224 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
225 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
226 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
227#endif
228
229 attr->dname = dget(dir);
230 return dir;
231}
232EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
233
234#endif
235
