Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
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/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 */
17int 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}
39EXPORT_SYMBOL_GPL(setup_fault_attr);
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 /* No need to check any other properties if the probability is 0 */
105 if (attr->probability == 0)
106 return false;
107
108 if (attr->task_filter && !fail_task(attr, current))
109 return false;
110
111 if (atomic_read(&attr->times) == 0)
112 return false;
113
114 if (atomic_read(&attr->space) > size) {
115 atomic_sub(size, &attr->space);
116 return false;
117 }
118
119 if (attr->interval > 1) {
120 attr->count++;
121 if (attr->count % attr->interval)
122 return false;
123 }
124
125 if (attr->probability <= prandom_u32() % 100)
126 return false;
127
128 if (!fail_stacktrace(attr))
129 return false;
130
131 fail_dump(attr);
132
133 if (atomic_read(&attr->times) != -1)
134 atomic_dec_not_zero(&attr->times);
135
136 return true;
137}
138EXPORT_SYMBOL_GPL(should_fail);
139
140#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
141
142static int debugfs_ul_set(void *data, u64 val)
143{
144 *(unsigned long *)data = val;
145 return 0;
146}
147
148static int debugfs_ul_get(void *data, u64 *val)
149{
150 *val = *(unsigned long *)data;
151 return 0;
152}
153
154DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
155
156static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
157 struct dentry *parent, unsigned long *value)
158{
159 return debugfs_create_file(name, mode, parent, value, &fops_ul);
160}
161
162#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
163
164static int debugfs_stacktrace_depth_set(void *data, u64 val)
165{
166 *(unsigned long *)data =
167 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
168
169 return 0;
170}
171
172DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
173 debugfs_stacktrace_depth_set, "%llu\n");
174
175static struct dentry *debugfs_create_stacktrace_depth(
176 const char *name, umode_t mode,
177 struct dentry *parent, unsigned long *value)
178{
179 return debugfs_create_file(name, mode, parent, value,
180 &fops_stacktrace_depth);
181}
182
183#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
184
185struct dentry *fault_create_debugfs_attr(const char *name,
186 struct dentry *parent, struct fault_attr *attr)
187{
188 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
189 struct dentry *dir;
190
191 dir = debugfs_create_dir(name, parent);
192 if (!dir)
193 return ERR_PTR(-ENOMEM);
194
195 if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
196 goto fail;
197 if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
198 goto fail;
199 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
200 goto fail;
201 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
202 goto fail;
203 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
204 goto fail;
205 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
206 goto fail;
207
208#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
209
210 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
211 &attr->stacktrace_depth))
212 goto fail;
213 if (!debugfs_create_ul("require-start", mode, dir,
214 &attr->require_start))
215 goto fail;
216 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
217 goto fail;
218 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
219 goto fail;
220 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
221 goto fail;
222
223#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
224
225 return dir;
226fail:
227 debugfs_remove_recursive(dir);
228
229 return ERR_PTR(-ENOMEM);
230}
231EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
232
233#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */