linux/lib/fault-inject.c
Akinobu Mita 4668c7a294 fault-inject: allow configuration via configfs
This provides a helper function to allow configuration of fault-injection
for configfs-based drivers.

The config items created by this function have the same interface as the
one created under debugfs by fault_create_debugfs_attr().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/20230327143733.14599-2-akinobu.mita@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-04-13 07:38:54 -06:00

438 lines
11 KiB
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 || (found && !attr->reject_start && !attr->reject_end))
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_ex(struct fault_attr *attr, ssize_t size, int flags)
{
bool stack_checked = false;
if (in_task()) {
unsigned int fail_nth = READ_ONCE(current->fail_nth);
if (fail_nth) {
if (!fail_stacktrace(attr))
return false;
stack_checked = true;
fail_nth--;
WRITE_ONCE(current->fail_nth, fail_nth);
if (!fail_nth)
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 (!stack_checked && !fail_stacktrace(attr))
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 <= get_random_u32_below(100))
return false;
fail:
if (!(flags & FAULT_NOWARN))
fail_dump(attr);
if (atomic_read(&attr->times) != -1)
atomic_dec_not_zero(&attr->times);
return true;
}
bool should_fail(struct fault_attr *attr, ssize_t size)
{
return should_fail_ex(attr, size, 0);
}
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_xul("require-start", mode, dir, &attr->require_start);
debugfs_create_xul("require-end", mode, dir, &attr->require_end);
debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
debugfs_create_xul("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 */
#ifdef CONFIG_FAULT_INJECTION_CONFIGFS
/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */
static ssize_t fault_uint_attr_show(unsigned int val, char *page)
{
return snprintf(page, PAGE_SIZE, "%u\n", val);
}
static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
{
return snprintf(page, PAGE_SIZE, "%lu\n", val);
}
static ssize_t fault_bool_attr_show(bool val, char *page)
{
return snprintf(page, PAGE_SIZE, "%u\n", val);
}
static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page)
{
return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val));
}
static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count)
{
unsigned int tmp;
int result;
result = kstrtouint(page, 0, &tmp);
if (result < 0)
return result;
*val = tmp;
return count;
}
static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count)
{
int result;
unsigned long tmp;
result = kstrtoul(page, 0, &tmp);
if (result < 0)
return result;
*val = tmp;
return count;
}
static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count)
{
bool tmp;
int result;
result = kstrtobool(page, &tmp);
if (result < 0)
return result;
*val = tmp;
return count;
}
static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count)
{
int tmp;
int result;
result = kstrtoint(page, 0, &tmp);
if (result < 0)
return result;
atomic_set(val, tmp);
return count;
}
#define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \
static struct configfs_attribute _pfx##attr_##_name = { \
.ca_name = _attr_name, \
.ca_mode = 0644, \
.ca_owner = THIS_MODULE, \
.show = _pfx##_name##_show, \
.store = _pfx##_name##_store, \
}
static struct fault_config *to_fault_config(struct config_item *item)
{
return container_of(to_config_group(item), struct fault_config, group);
}
#define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \
static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \
{ \
return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \
} \
static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \
{ \
struct fault_config *config = to_fault_config(item); \
return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \
} \
CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME)
#define FAULT_CONFIGFS_ATTR(NAME, TYPE) \
FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE)
FAULT_CONFIGFS_ATTR(probability, ulong);
FAULT_CONFIGFS_ATTR(interval, ulong);
FAULT_CONFIGFS_ATTR(times, atomic_t);
FAULT_CONFIGFS_ATTR(space, atomic_t);
FAULT_CONFIGFS_ATTR(verbose, ulong);
FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
ratelimit_state.interval, uint);
FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
ratelimit_state.burst, uint);
FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page)
{
return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page);
}
static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page,
size_t count)
{
int result;
unsigned long tmp;
result = kstrtoul(page, 0, &tmp);
if (result < 0)
return result;
to_fault_config(item)->attr.stacktrace_depth =
min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH);
return count;
}
CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");
static ssize_t fault_xul_attr_show(unsigned long val, char *page)
{
return snprintf(page, PAGE_SIZE,
sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val);
}
static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count)
{
return fault_ulong_attr_store(val, page, count);
}
FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
static struct configfs_attribute *fault_config_attrs[] = {
&fault_attr_probability,
&fault_attr_interval,
&fault_attr_times,
&fault_attr_space,
&fault_attr_verbose,
&fault_attr_ratelimit_interval,
&fault_attr_ratelimit_burst,
&fault_attr_task_filter,
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
&fault_attr_stacktrace_depth,
&fault_attr_require_start,
&fault_attr_require_end,
&fault_attr_reject_start,
&fault_attr_reject_end,
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
NULL,
};
static const struct config_item_type fault_config_type = {
.ct_attrs = fault_config_attrs,
.ct_owner = THIS_MODULE,
};
void fault_config_init(struct fault_config *config, const char *name)
{
config_group_init_type_name(&config->group, name, &fault_config_type);
}
EXPORT_SYMBOL_GPL(fault_config_init);
#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */