Merge branch 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
[linux-2.6-block.git] / lib / fault-inject.c
1 // SPDX-License-Identifier: GPL-2.0-only
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  * setup_fault_attr() is a helper function for various __setup handlers, so it
16  * returns 0 on error, because that is what __setup handlers do.
17  */
18 int 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         /* "<interval>,<probability>,<space>,<times>" */
26         if (sscanf(str, "%lu,%lu,%d,%d",
27                         &interval, &probability, &space, &times) < 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 }
40 EXPORT_SYMBOL_GPL(setup_fault_attr);
41
42 static 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
58 static 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
67 static 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
91 static inline bool fail_stacktrace(struct fault_attr *attr)
92 {
93         return true;
94 }
95
96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
97
98 /*
99  * This code is stolen from failmalloc-1.0
100  * http://www.nongnu.org/failmalloc/
101  */
102
103 bool 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                         if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
110                                 goto fail;
111
112                         return false;
113                 }
114         }
115
116         /* No need to check any other properties if the probability is 0 */
117         if (attr->probability == 0)
118                 return false;
119
120         if (attr->task_filter && !fail_task(attr, current))
121                 return false;
122
123         if (atomic_read(&attr->times) == 0)
124                 return false;
125
126         if (atomic_read(&attr->space) > size) {
127                 atomic_sub(size, &attr->space);
128                 return false;
129         }
130
131         if (attr->interval > 1) {
132                 attr->count++;
133                 if (attr->count % attr->interval)
134                         return false;
135         }
136
137         if (attr->probability <= prandom_u32() % 100)
138                 return false;
139
140         if (!fail_stacktrace(attr))
141                 return false;
142
143 fail:
144         fail_dump(attr);
145
146         if (atomic_read(&attr->times) != -1)
147                 atomic_dec_not_zero(&attr->times);
148
149         return true;
150 }
151 EXPORT_SYMBOL_GPL(should_fail);
152
153 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
154
155 static int debugfs_ul_set(void *data, u64 val)
156 {
157         *(unsigned long *)data = val;
158         return 0;
159 }
160
161 static int debugfs_ul_get(void *data, u64 *val)
162 {
163         *val = *(unsigned long *)data;
164         return 0;
165 }
166
167 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
168
169 static void debugfs_create_ul(const char *name, umode_t mode,
170                               struct dentry *parent, unsigned long *value)
171 {
172         debugfs_create_file(name, mode, parent, value, &fops_ul);
173 }
174
175 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
176
177 static int debugfs_stacktrace_depth_set(void *data, u64 val)
178 {
179         *(unsigned long *)data =
180                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
181
182         return 0;
183 }
184
185 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
186                         debugfs_stacktrace_depth_set, "%llu\n");
187
188 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
189                                             struct dentry *parent,
190                                             unsigned long *value)
191 {
192         debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
193 }
194
195 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
196
197 struct dentry *fault_create_debugfs_attr(const char *name,
198                         struct dentry *parent, struct fault_attr *attr)
199 {
200         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
201         struct dentry *dir;
202
203         dir = debugfs_create_dir(name, parent);
204         if (IS_ERR(dir))
205                 return dir;
206
207         debugfs_create_ul("probability", mode, dir, &attr->probability);
208         debugfs_create_ul("interval", mode, dir, &attr->interval);
209         debugfs_create_atomic_t("times", mode, dir, &attr->times);
210         debugfs_create_atomic_t("space", mode, dir, &attr->space);
211         debugfs_create_ul("verbose", mode, dir, &attr->verbose);
212         debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
213                            &attr->ratelimit_state.interval);
214         debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
215                            &attr->ratelimit_state.burst);
216         debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
217
218 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
219         debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
220                                         &attr->stacktrace_depth);
221         debugfs_create_ul("require-start", mode, dir, &attr->require_start);
222         debugfs_create_ul("require-end", mode, dir, &attr->require_end);
223         debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
224         debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
225 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
226
227         attr->dname = dget(dir);
228         return dir;
229 }
230 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
231
232 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */