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#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/module.h>
#include <linux/interrupt.h>
#include <linux/stacktrace.h>
#include <linux/kallsyms.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 __init 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;
}
static void fail_dump(struct fault_attr *attr)
{
if (attr->verbose > 0)
printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
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_interrupt() && task->make_it_fail;
}
#define MAX_STACK_TRACE_DEPTH 32
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
static bool fail_stacktrace(struct fault_attr *attr)
{
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;
trace.max_entries = depth;
trace.skip = 1;
save_stack_trace(&trace);
for (n = 0; n < trace.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 (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 <= random32() % 100)
return false;
if (!fail_stacktrace(attr))
return false;
fail_dump(attr);
if (atomic_read(&attr->times) != -1)
atomic_dec_not_zero(&attr->times);
return true;
}
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
static int debugfs_ul_set(void *data, u64 val)
{
*(unsigned long *)data = val;
return 0;
}
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
{
*(unsigned long *)data =
val < MAX_STACK_TRACE_DEPTH ?
val : MAX_STACK_TRACE_DEPTH;
return 0;
}
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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 struct dentry *debugfs_create_ul(const char *name, mode_t mode,
struct dentry *parent, unsigned long *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_ul);
}
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
const char *name, mode_t mode,
struct dentry *parent, unsigned long *value)
{
return debugfs_create_file(name, mode, parent, value,
&fops_ul_MAX_STACK_TRACE_DEPTH);
}
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
static int debugfs_atomic_t_set(void *data, u64 val)
{
atomic_set((atomic_t *)data, val);
return 0;
}
static int debugfs_atomic_t_get(void *data, u64 *val)
{
*val = atomic_read((atomic_t *)data);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
debugfs_atomic_t_set, "%lld\n");
static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
struct dentry *parent, atomic_t *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
}
void cleanup_fault_attr_dentries(struct fault_attr *attr)
{
debugfs_remove(attr->dentries.probability_file);
attr->dentries.probability_file = NULL;
debugfs_remove(attr->dentries.interval_file);
attr->dentries.interval_file = NULL;
debugfs_remove(attr->dentries.times_file);
attr->dentries.times_file = NULL;
debugfs_remove(attr->dentries.space_file);
attr->dentries.space_file = NULL;
debugfs_remove(attr->dentries.verbose_file);
attr->dentries.verbose_file = NULL;
debugfs_remove(attr->dentries.task_filter_file);
attr->dentries.task_filter_file = NULL;
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
debugfs_remove(attr->dentries.stacktrace_depth_file);
attr->dentries.stacktrace_depth_file = NULL;
debugfs_remove(attr->dentries.require_start_file);
attr->dentries.require_start_file = NULL;
debugfs_remove(attr->dentries.require_end_file);
attr->dentries.require_end_file = NULL;
debugfs_remove(attr->dentries.reject_start_file);
attr->dentries.reject_start_file = NULL;
debugfs_remove(attr->dentries.reject_end_file);
attr->dentries.reject_end_file = NULL;
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
if (attr->dentries.dir)
WARN_ON(!simple_empty(attr->dentries.dir));
debugfs_remove(attr->dentries.dir);
attr->dentries.dir = NULL;
}
int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
{
mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
struct dentry *dir;
memset(&attr->dentries, 0, sizeof(attr->dentries));
dir = debugfs_create_dir(name, NULL);
if (!dir)
goto fail;
attr->dentries.dir = dir;
attr->dentries.probability_file =
debugfs_create_ul("probability", mode, dir, &attr->probability);
attr->dentries.interval_file =
debugfs_create_ul("interval", mode, dir, &attr->interval);
attr->dentries.times_file =
debugfs_create_atomic_t("times", mode, dir, &attr->times);
attr->dentries.space_file =
debugfs_create_atomic_t("space", mode, dir, &attr->space);
attr->dentries.verbose_file =
debugfs_create_ul("verbose", mode, dir, &attr->verbose);
attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
mode, dir, &attr->task_filter);
if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
!attr->dentries.times_file || !attr->dentries.space_file ||
!attr->dentries.verbose_file || !attr->dentries.task_filter_file)
goto fail;
#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
attr->dentries.stacktrace_depth_file =
debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
"stacktrace-depth", mode, dir, &attr->stacktrace_depth);
attr->dentries.require_start_file =
debugfs_create_ul("require-start", mode, dir, &attr->require_start);
attr->dentries.require_end_file =
debugfs_create_ul("require-end", mode, dir, &attr->require_end);
attr->dentries.reject_start_file =
debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
attr->dentries.reject_end_file =
debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
if (!attr->dentries.stacktrace_depth_file ||
!attr->dentries.require_start_file ||
!attr->dentries.require_end_file ||
!attr->dentries.reject_start_file ||
!attr->dentries.reject_end_file)
goto fail;
#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
return 0;
fail:
cleanup_fault_attr_dentries(attr);
return -ENOMEM;
}
#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
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