tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/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 */
17int __init 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, ×) < 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
40static void fail_dump(struct fault_attr *attr)
41{
42 if (attr->verbose > 0)
43 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
44 if (attr->verbose > 1)
45 dump_stack();
46}
47
48#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
49
50static bool fail_task(struct fault_attr *attr, struct task_struct *task)
51{
52 return !in_interrupt() && task->make_it_fail;
53}
54
55#define MAX_STACK_TRACE_DEPTH 32
56
57#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
58
59static bool fail_stacktrace(struct fault_attr *attr)
60{
61 struct stack_trace trace;
62 int depth = attr->stacktrace_depth;
63 unsigned long entries[MAX_STACK_TRACE_DEPTH];
64 int n;
65 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
66
67 if (depth == 0)
68 return found;
69
70 trace.nr_entries = 0;
71 trace.entries = entries;
72 trace.max_entries = depth;
73 trace.skip = 1;
74
75 save_stack_trace(&trace);
76 for (n = 0; n < trace.nr_entries; n++) {
77 if (attr->reject_start <= entries[n] &&
78 entries[n] < attr->reject_end)
79 return false;
80 if (attr->require_start <= entries[n] &&
81 entries[n] < attr->require_end)
82 found = true;
83 }
84 return found;
85}
86
87#else
88
89static inline bool fail_stacktrace(struct fault_attr *attr)
90{
91 return true;
92}
93
94#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
95
96/*
97 * This code is stolen from failmalloc-1.0
98 * http://www.nongnu.org/failmalloc/
99 */
100
101bool should_fail(struct fault_attr *attr, ssize_t size)
102{
103 if (attr->task_filter && !fail_task(attr, current))
104 return false;
105
106 if (atomic_read(&attr->times) == 0)
107 return false;
108
109 if (atomic_read(&attr->space) > size) {
110 atomic_sub(size, &attr->space);
111 return false;
112 }
113
114 if (attr->interval > 1) {
115 attr->count++;
116 if (attr->count % attr->interval)
117 return false;
118 }
119
120 if (attr->probability <= random32() % 100)
121 return false;
122
123 if (!fail_stacktrace(attr))
124 return false;
125
126 fail_dump(attr);
127
128 if (atomic_read(&attr->times) != -1)
129 atomic_dec_not_zero(&attr->times);
130
131 return true;
132}
133
134#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
135
136static int debugfs_ul_set(void *data, u64 val)
137{
138 *(unsigned long *)data = val;
139 return 0;
140}
141
142static int debugfs_ul_get(void *data, u64 *val)
143{
144 *val = *(unsigned long *)data;
145 return 0;
146}
147
148DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
149
150static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
151 struct dentry *parent, unsigned long *value)
152{
153 return debugfs_create_file(name, mode, parent, value, &fops_ul);
154}
155
156#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
157
158static int debugfs_stacktrace_depth_set(void *data, u64 val)
159{
160 *(unsigned long *)data =
161 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
162
163 return 0;
164}
165
166DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
167 debugfs_stacktrace_depth_set, "%llu\n");
168
169static struct dentry *debugfs_create_stacktrace_depth(
170 const char *name, mode_t mode,
171 struct dentry *parent, unsigned long *value)
172{
173 return debugfs_create_file(name, mode, parent, value,
174 &fops_stacktrace_depth);
175}
176
177#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
178
179static int debugfs_atomic_t_set(void *data, u64 val)
180{
181 atomic_set((atomic_t *)data, val);
182 return 0;
183}
184
185static int debugfs_atomic_t_get(void *data, u64 *val)
186{
187 *val = atomic_read((atomic_t *)data);
188 return 0;
189}
190
191DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
192 debugfs_atomic_t_set, "%lld\n");
193
194static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
195 struct dentry *parent, atomic_t *value)
196{
197 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
198}
199
200struct dentry *fault_create_debugfs_attr(const char *name,
201 struct dentry *parent, struct fault_attr *attr)
202{
203 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
204 struct dentry *dir;
205
206 dir = debugfs_create_dir(name, parent);
207 if (!dir)
208 return ERR_PTR(-ENOMEM);
209
210 if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
211 goto fail;
212 if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
213 goto fail;
214 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
215 goto fail;
216 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
217 goto fail;
218 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
219 goto fail;
220 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
221 goto fail;
222
223#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
224
225 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
226 &attr->stacktrace_depth))
227 goto fail;
228 if (!debugfs_create_ul("require-start", mode, dir,
229 &attr->require_start))
230 goto fail;
231 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
232 goto fail;
233 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
234 goto fail;
235 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
236 goto fail;
237
238#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
239
240 return dir;
241fail:
242 debugfs_remove_recursive(dir);
243
244 return ERR_PTR(-ENOMEM);
245}
246
247#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */