fault-inject.c 6.2 KB
Newer Older
1 2 3
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/random.h>
4
#include <linux/sched.h>
5 6 7
#include <linux/stat.h>
#include <linux/types.h>
#include <linux/fs.h>
8
#include <linux/export.h>
9
#include <linux/interrupt.h>
10
#include <linux/stacktrace.h>
11 12 13 14 15 16
#include <linux/fault-inject.h>

/*
 * setup_fault_attr() is a helper function for various __setup handlers, so it
 * returns 0 on error, because that is what __setup handlers do.
 */
17
int setup_fault_attr(struct fault_attr *attr, char *str)
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
{
	unsigned long probability;
	unsigned long interval;
	int times;
	int space;

	/* "<interval>,<probability>,<space>,<times>" */
	if (sscanf(str, "%lu,%lu,%d,%d",
			&interval, &probability, &space, &times) < 4) {
		printk(KERN_WARNING
			"FAULT_INJECTION: failed to parse arguments\n");
		return 0;
	}

	attr->probability = probability;
	attr->interval = interval;
	atomic_set(&attr->times, times);
	atomic_set(&attr->space, space);

	return 1;
}
39
EXPORT_SYMBOL_GPL(setup_fault_attr);
40 41 42

static void fail_dump(struct fault_attr *attr)
{
43 44 45 46
	if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
		       "name %pd, interval %lu, probability %lu, "
		       "space %d, times %d\n", attr->dname,
47
		       attr->interval, attr->probability,
48 49 50 51 52
		       atomic_read(&attr->space),
		       atomic_read(&attr->times));
		if (attr->verbose > 1)
			dump_stack();
	}
53 54 55 56
}

#define atomic_dec_not_zero(v)		atomic_add_unless((v), -1, 0)

57
static bool fail_task(struct fault_attr *attr, struct task_struct *task)
58
{
59
	return in_task() && task->make_it_fail;
60 61
}

62 63
#define MAX_STACK_TRACE_DEPTH 32

64
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
65

66
static bool fail_stacktrace(struct fault_attr *attr)
67 68 69 70 71 72 73 74 75 76 77 78
{
	struct stack_trace trace;
	int depth = attr->stacktrace_depth;
	unsigned long entries[MAX_STACK_TRACE_DEPTH];
	int n;
	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);

	if (depth == 0)
		return found;

	trace.nr_entries = 0;
	trace.entries = entries;
79
	trace.max_entries = depth;
80 81
	trace.skip = 1;

82
	save_stack_trace(&trace);
83 84 85
	for (n = 0; n < trace.nr_entries; n++) {
		if (attr->reject_start <= entries[n] &&
			       entries[n] < attr->reject_end)
86
			return false;
87 88
		if (attr->require_start <= entries[n] &&
			       entries[n] < attr->require_end)
89
			found = true;
90 91 92 93 94 95
	}
	return found;
}

#else

96
static inline bool fail_stacktrace(struct fault_attr *attr)
97
{
98
	return true;
99 100
}

101
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
102

103 104 105 106 107
/*
 * This code is stolen from failmalloc-1.0
 * http://www.nongnu.org/failmalloc/
 */

108
bool should_fail(struct fault_attr *attr, ssize_t size)
109
{
110 111 112
	if (in_task()) {
		unsigned int fail_nth = READ_ONCE(current->fail_nth);

113 114 115
		if (fail_nth) {
			if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
				goto fail;
116

117 118
			return false;
		}
119 120
	}

121 122 123 124
	/* No need to check any other properties if the probability is 0 */
	if (attr->probability == 0)
		return false;

125
	if (attr->task_filter && !fail_task(attr, current))
126
		return false;
127

128
	if (atomic_read(&attr->times) == 0)
129
		return false;
130 131 132

	if (atomic_read(&attr->space) > size) {
		atomic_sub(size, &attr->space);
133
		return false;
134 135 136 137 138
	}

	if (attr->interval > 1) {
		attr->count++;
		if (attr->count % attr->interval)
139
			return false;
140 141
	}

142
	if (attr->probability <= prandom_u32() % 100)
143
		return false;
144

145 146
	if (!fail_stacktrace(attr))
		return false;
147

148
fail:
149 150 151 152 153
	fail_dump(attr);

	if (atomic_read(&attr->times) != -1)
		atomic_dec_not_zero(&attr->times);

154
	return true;
155
}
156
EXPORT_SYMBOL_GPL(should_fail);
157 158 159

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

160
static int debugfs_ul_set(void *data, u64 val)
161 162
{
	*(unsigned long *)data = val;
163
	return 0;
164 165
}

166
static int debugfs_ul_get(void *data, u64 *val)
167
{
168 169
	*val = *(unsigned long *)data;
	return 0;
170 171 172 173
}

DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");

Al Viro's avatar
Al Viro committed
174
static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
175 176 177 178 179
				struct dentry *parent, unsigned long *value)
{
	return debugfs_create_file(name, mode, parent, value, &fops_ul);
}

180
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
181

182 183 184 185 186 187 188 189 190 191 192 193
static int debugfs_stacktrace_depth_set(void *data, u64 val)
{
	*(unsigned long *)data =
		min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);

	return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
			debugfs_stacktrace_depth_set, "%llu\n");

static struct dentry *debugfs_create_stacktrace_depth(
Al Viro's avatar
Al Viro committed
194
	const char *name, umode_t mode,
195 196 197
	struct dentry *parent, unsigned long *value)
{
	return debugfs_create_file(name, mode, parent, value,
198
				   &fops_stacktrace_depth);
199
}
200

201
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
202

203 204
struct dentry *fault_create_debugfs_attr(const char *name,
			struct dentry *parent, struct fault_attr *attr)
205
{
Al Viro's avatar
Al Viro committed
206
	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
207 208
	struct dentry *dir;

209
	dir = debugfs_create_dir(name, parent);
210
	if (!dir)
211
		return ERR_PTR(-ENOMEM);
212

213 214 215 216 217 218 219 220 221 222
	if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
		goto fail;
	if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
		goto fail;
	if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
		goto fail;
	if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
		goto fail;
	if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
		goto fail;
223 224 225 226 227 228
	if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
				&attr->ratelimit_state.interval))
		goto fail;
	if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
				&attr->ratelimit_state.burst))
		goto fail;
229
	if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
230 231 232 233
		goto fail;

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

234 235 236 237 238 239 240 241 242 243 244
	if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
				&attr->stacktrace_depth))
		goto fail;
	if (!debugfs_create_ul("require-start", mode, dir,
				&attr->require_start))
		goto fail;
	if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
		goto fail;
	if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
		goto fail;
	if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
245 246
		goto fail;

247 248
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

249
	attr->dname = dget(dir);
250
	return dir;
251
fail:
252
	debugfs_remove_recursive(dir);
253

254
	return ERR_PTR(-ENOMEM);
255
}
256
EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
257 258

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */