Root/lib/fault-inject.c

Source at commit b386be689295730688885552666ea40b2e639b14 created 8 years 11 months ago.
By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters."
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 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}
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    if (attr->task_filter && !fail_task(attr, current))
105        return false;
106
107    if (atomic_read(&attr->times) == 0)
108        return false;
109
110    if (atomic_read(&attr->space) > size) {
111        atomic_sub(size, &attr->space);
112        return false;
113    }
114
115    if (attr->interval > 1) {
116        attr->count++;
117        if (attr->count % attr->interval)
118            return false;
119    }
120
121    if (attr->probability <= random32() % 100)
122        return false;
123
124    if (!fail_stacktrace(attr))
125        return false;
126
127    fail_dump(attr);
128
129    if (atomic_read(&attr->times) != -1)
130        atomic_dec_not_zero(&attr->times);
131
132    return true;
133}
134EXPORT_SYMBOL_GPL(should_fail);
135
136#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
137
138static int debugfs_ul_set(void *data, u64 val)
139{
140    *(unsigned long *)data = val;
141    return 0;
142}
143
144static int debugfs_ul_get(void *data, u64 *val)
145{
146    *val = *(unsigned long *)data;
147    return 0;
148}
149
150DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
151
152static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
153                struct dentry *parent, unsigned long *value)
154{
155    return debugfs_create_file(name, mode, parent, value, &fops_ul);
156}
157
158#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
159
160static int debugfs_stacktrace_depth_set(void *data, u64 val)
161{
162    *(unsigned long *)data =
163        min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
164
165    return 0;
166}
167
168DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
169            debugfs_stacktrace_depth_set, "%llu\n");
170
171static struct dentry *debugfs_create_stacktrace_depth(
172    const char *name, umode_t mode,
173    struct dentry *parent, unsigned long *value)
174{
175    return debugfs_create_file(name, mode, parent, value,
176                   &fops_stacktrace_depth);
177}
178
179#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
180
181static int debugfs_atomic_t_set(void *data, u64 val)
182{
183    atomic_set((atomic_t *)data, val);
184    return 0;
185}
186
187static int debugfs_atomic_t_get(void *data, u64 *val)
188{
189    *val = atomic_read((atomic_t *)data);
190    return 0;
191}
192
193DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
194            debugfs_atomic_t_set, "%lld\n");
195
196static struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
197                struct dentry *parent, atomic_t *value)
198{
199    return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
200}
201
202struct dentry *fault_create_debugfs_attr(const char *name,
203            struct dentry *parent, struct fault_attr *attr)
204{
205    umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
206    struct dentry *dir;
207
208    dir = debugfs_create_dir(name, parent);
209    if (!dir)
210        return ERR_PTR(-ENOMEM);
211
212    if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
213        goto fail;
214    if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
215        goto fail;
216    if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
217        goto fail;
218    if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
219        goto fail;
220    if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
221        goto fail;
222    if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
223        goto fail;
224
225#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
226
227    if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
228                &attr->stacktrace_depth))
229        goto fail;
230    if (!debugfs_create_ul("require-start", mode, dir,
231                &attr->require_start))
232        goto fail;
233    if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
234        goto fail;
235    if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
236        goto fail;
237    if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
238        goto fail;
239
240#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
241
242    return dir;
243fail:
244    debugfs_remove_recursive(dir);
245
246    return ERR_PTR(-ENOMEM);
247}
248EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
249
250#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
251

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