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>
9 #include <linux/export.h>
10 #include <linux/interrupt.h>
11 #include <linux/stacktrace.h>
12 #include <linux/fault-inject.h>
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.
18 int setup_fault_attr(struct fault_attr
*attr
, char *str
)
20 unsigned long probability
;
21 unsigned long interval
;
25 /* "<interval>,<probability>,<space>,<times>" */
26 if (sscanf(str
, "%lu,%lu,%d,%d",
27 &interval
, &probability
, &space
, ×
) < 4) {
29 "FAULT_INJECTION: failed to parse arguments\n");
33 attr
->probability
= probability
;
34 attr
->interval
= interval
;
35 atomic_set(&attr
->times
, times
);
36 atomic_set(&attr
->space
, space
);
40 EXPORT_SYMBOL_GPL(setup_fault_attr
);
42 static void fail_dump(struct fault_attr
*attr
)
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)
56 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
58 static bool fail_task(struct fault_attr
*attr
, struct task_struct
*task
)
60 return in_task() && task
->make_it_fail
;
63 #define MAX_STACK_TRACE_DEPTH 32
65 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
67 static bool fail_stacktrace(struct fault_attr
*attr
)
69 int depth
= attr
->stacktrace_depth
;
70 unsigned long entries
[MAX_STACK_TRACE_DEPTH
];
72 bool found
= (attr
->require_start
== 0 && attr
->require_end
== ULONG_MAX
);
74 if (depth
== 0 || (found
&& !attr
->reject_start
&& !attr
->reject_end
))
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
)
82 if (attr
->require_start
<= entries
[n
] &&
83 entries
[n
] < attr
->require_end
)
91 static inline bool fail_stacktrace(struct fault_attr
*attr
)
96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
99 * This code is stolen from failmalloc-1.0
100 * http://www.nongnu.org/failmalloc/
103 bool should_fail_ex(struct fault_attr
*attr
, ssize_t size
, int flags
)
105 bool stack_checked
= false;
108 unsigned int fail_nth
= READ_ONCE(current
->fail_nth
);
111 if (!fail_stacktrace(attr
))
114 stack_checked
= true;
116 WRITE_ONCE(current
->fail_nth
, fail_nth
);
124 /* No need to check any other properties if the probability is 0 */
125 if (attr
->probability
== 0)
128 if (attr
->task_filter
&& !fail_task(attr
, current
))
131 if (atomic_read(&attr
->times
) == 0)
134 if (!stack_checked
&& !fail_stacktrace(attr
))
137 if (atomic_read(&attr
->space
) > size
) {
138 atomic_sub(size
, &attr
->space
);
142 if (attr
->interval
> 1) {
144 if (attr
->count
% attr
->interval
)
148 if (attr
->probability
<= get_random_u32_below(100))
152 if (!(flags
& FAULT_NOWARN
))
155 if (atomic_read(&attr
->times
) != -1)
156 atomic_dec_not_zero(&attr
->times
);
161 bool should_fail(struct fault_attr
*attr
, ssize_t size
)
163 return should_fail_ex(attr
, size
, 0);
165 EXPORT_SYMBOL_GPL(should_fail
);
167 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
169 static int debugfs_ul_set(void *data
, u64 val
)
171 *(unsigned long *)data
= val
;
175 static int debugfs_ul_get(void *data
, u64
*val
)
177 *val
= *(unsigned long *)data
;
181 DEFINE_SIMPLE_ATTRIBUTE(fops_ul
, debugfs_ul_get
, debugfs_ul_set
, "%llu\n");
183 static void debugfs_create_ul(const char *name
, umode_t mode
,
184 struct dentry
*parent
, unsigned long *value
)
186 debugfs_create_file(name
, mode
, parent
, value
, &fops_ul
);
189 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
191 static int debugfs_stacktrace_depth_set(void *data
, u64 val
)
193 *(unsigned long *)data
=
194 min_t(unsigned long, val
, MAX_STACK_TRACE_DEPTH
);
199 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth
, debugfs_ul_get
,
200 debugfs_stacktrace_depth_set
, "%llu\n");
202 static void debugfs_create_stacktrace_depth(const char *name
, umode_t mode
,
203 struct dentry
*parent
,
204 unsigned long *value
)
206 debugfs_create_file(name
, mode
, parent
, value
, &fops_stacktrace_depth
);
209 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
211 struct dentry
*fault_create_debugfs_attr(const char *name
,
212 struct dentry
*parent
, struct fault_attr
*attr
)
214 umode_t mode
= S_IFREG
| S_IRUSR
| S_IWUSR
;
217 dir
= debugfs_create_dir(name
, parent
);
221 debugfs_create_ul("probability", mode
, dir
, &attr
->probability
);
222 debugfs_create_ul("interval", mode
, dir
, &attr
->interval
);
223 debugfs_create_atomic_t("times", mode
, dir
, &attr
->times
);
224 debugfs_create_atomic_t("space", mode
, dir
, &attr
->space
);
225 debugfs_create_ul("verbose", mode
, dir
, &attr
->verbose
);
226 debugfs_create_u32("verbose_ratelimit_interval_ms", mode
, dir
,
227 &attr
->ratelimit_state
.interval
);
228 debugfs_create_u32("verbose_ratelimit_burst", mode
, dir
,
229 &attr
->ratelimit_state
.burst
);
230 debugfs_create_bool("task-filter", mode
, dir
, &attr
->task_filter
);
232 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
233 debugfs_create_stacktrace_depth("stacktrace-depth", mode
, dir
,
234 &attr
->stacktrace_depth
);
235 debugfs_create_xul("require-start", mode
, dir
, &attr
->require_start
);
236 debugfs_create_xul("require-end", mode
, dir
, &attr
->require_end
);
237 debugfs_create_xul("reject-start", mode
, dir
, &attr
->reject_start
);
238 debugfs_create_xul("reject-end", mode
, dir
, &attr
->reject_end
);
239 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
241 attr
->dname
= dget(dir
);
244 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr
);
246 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */