[linux-2.6-block.git] / lib / fault-inject.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/stacktrace.h>
#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.
 */
int setup_fault_attr(struct fault_attr *attr, char *str)
{
	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;
}
EXPORT_SYMBOL_GPL(setup_fault_attr);

static void fail_dump(struct fault_attr *attr)
{
	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,
		       attr->interval, attr->probability,
		       atomic_read(&attr->space),
		       atomic_read(&attr->times));
		if (attr->verbose > 1)
			dump_stack();
	}
}

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

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

#define MAX_STACK_TRACE_DEPTH 32

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

static bool fail_stacktrace(struct fault_attr *attr)
{
	int depth = attr->stacktrace_depth;
	unsigned long entries[MAX_STACK_TRACE_DEPTH];
	int n, nr_entries;
	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);

	if (depth == 0)
		return found;

	nr_entries = stack_trace_save(entries, depth, 1);
	for (n = 0; n < nr_entries; n++) {
		if (attr->reject_start <= entries[n] &&
			       entries[n] < attr->reject_end)
			return false;
		if (attr->require_start <= entries[n] &&
			       entries[n] < attr->require_end)
			found = true;
	}
	return found;
}

#else

static inline bool fail_stacktrace(struct fault_attr *attr)
{
	return true;
}

#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

/*
 * This code is stolen from failmalloc-1.0
 * http://www.nongnu.org/failmalloc/
 */

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

		if (fail_nth) {
			if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
				goto fail;

			return false;
		}
	}

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

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

	if (atomic_read(&attr->times) == 0)
		return false;

	if (atomic_read(&attr->space) > size) {
		atomic_sub(size, &attr->space);
		return false;
	}

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

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

	if (!fail_stacktrace(attr))
		return false;

fail:
	fail_dump(attr);

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

	return true;
}
EXPORT_SYMBOL_GPL(should_fail);

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

static int debugfs_ul_set(void *data, u64 val)
{
	*(unsigned long *)data = val;
	return 0;
}

static int debugfs_ul_get(void *data, u64 *val)
{
	*val = *(unsigned long *)data;
	return 0;
}

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

static void debugfs_create_ul(const char *name, umode_t mode,
			      struct dentry *parent, unsigned long *value)
{
	debugfs_create_file(name, mode, parent, value, &fops_ul);
}

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER

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 void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
					    struct dentry *parent,
					    unsigned long *value)
{
	debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
}

#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

struct dentry *fault_create_debugfs_attr(const char *name,
			struct dentry *parent, struct fault_attr *attr)
{
	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
	struct dentry *dir;

	dir = debugfs_create_dir(name, parent);
	if (IS_ERR(dir))
		return dir;

	debugfs_create_ul("probability", mode, dir, &attr->probability);
	debugfs_create_ul("interval", mode, dir, &attr->interval);
	debugfs_create_atomic_t("times", mode, dir, &attr->times);
	debugfs_create_atomic_t("space", mode, dir, &attr->space);
	debugfs_create_ul("verbose", mode, dir, &attr->verbose);
	debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
			   &attr->ratelimit_state.interval);
	debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
			   &attr->ratelimit_state.burst);
	debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);

#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
	debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
					&attr->stacktrace_depth);
	debugfs_create_ul("require-start", mode, dir, &attr->require_start);
	debugfs_create_ul("require-end", mode, dir, &attr->require_end);
	debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
	debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */

	attr->dname = dget(dir);
	return dir;
}
EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
Commit	Line	Data
	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 */