254 lines
6.2 KiB
C
254 lines
6.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/stat.h>
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/export.h>
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#include <linux/interrupt.h>
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#include <linux/stacktrace.h>
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#include <linux/fault-inject.h>
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/*
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* setup_fault_attr() is a helper function for various __setup handlers, so it
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* returns 0 on error, because that is what __setup handlers do.
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*/
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int setup_fault_attr(struct fault_attr *attr, char *str)
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{
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unsigned long probability;
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unsigned long interval;
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int times;
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int space;
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/* "<interval>,<probability>,<space>,<times>" */
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if (sscanf(str, "%lu,%lu,%d,%d",
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&interval, &probability, &space, ×) < 4) {
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printk(KERN_WARNING
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"FAULT_INJECTION: failed to parse arguments\n");
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return 0;
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}
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attr->probability = probability;
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attr->interval = interval;
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atomic_set(&attr->times, times);
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atomic_set(&attr->space, space);
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return 1;
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}
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EXPORT_SYMBOL_GPL(setup_fault_attr);
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static void fail_dump(struct fault_attr *attr)
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{
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if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
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printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
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"name %pd, interval %lu, probability %lu, "
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"space %d, times %d\n", attr->dname,
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attr->interval, attr->probability,
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atomic_read(&attr->space),
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atomic_read(&attr->times));
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if (attr->verbose > 1)
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dump_stack();
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}
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}
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#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
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static bool fail_task(struct fault_attr *attr, struct task_struct *task)
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{
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return in_task() && task->make_it_fail;
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}
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#define MAX_STACK_TRACE_DEPTH 32
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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static bool fail_stacktrace(struct fault_attr *attr)
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{
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int depth = attr->stacktrace_depth;
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unsigned long entries[MAX_STACK_TRACE_DEPTH];
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int n, nr_entries;
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bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
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if (depth == 0)
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return found;
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nr_entries = stack_trace_save(entries, depth, 1);
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for (n = 0; n < nr_entries; n++) {
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if (attr->reject_start <= entries[n] &&
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entries[n] < attr->reject_end)
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return false;
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if (attr->require_start <= entries[n] &&
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entries[n] < attr->require_end)
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found = true;
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}
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return found;
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}
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#else
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static inline bool fail_stacktrace(struct fault_attr *attr)
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{
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return true;
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}
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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/*
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* This code is stolen from failmalloc-1.0
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* http://www.nongnu.org/failmalloc/
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*/
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bool should_fail(struct fault_attr *attr, ssize_t size)
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{
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if (in_task()) {
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unsigned int fail_nth = READ_ONCE(current->fail_nth);
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if (fail_nth) {
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if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
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goto fail;
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return false;
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}
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}
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/* No need to check any other properties if the probability is 0 */
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if (attr->probability == 0)
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return false;
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if (attr->task_filter && !fail_task(attr, current))
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return false;
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if (atomic_read(&attr->times) == 0)
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return false;
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if (atomic_read(&attr->space) > size) {
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atomic_sub(size, &attr->space);
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return false;
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}
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if (attr->interval > 1) {
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attr->count++;
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if (attr->count % attr->interval)
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return false;
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}
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if (attr->probability <= prandom_u32() % 100)
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return false;
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if (!fail_stacktrace(attr))
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return false;
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fail:
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fail_dump(attr);
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if (atomic_read(&attr->times) != -1)
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atomic_dec_not_zero(&attr->times);
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return true;
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}
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EXPORT_SYMBOL_GPL(should_fail);
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#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
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static int debugfs_ul_set(void *data, u64 val)
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{
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*(unsigned long *)data = val;
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return 0;
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}
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static int debugfs_ul_get(void *data, u64 *val)
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{
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*val = *(unsigned long *)data;
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
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static struct dentry *debugfs_create_ul(const char *name, umode_t mode,
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struct dentry *parent, unsigned long *value)
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{
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return debugfs_create_file(name, mode, parent, value, &fops_ul);
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}
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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static int debugfs_stacktrace_depth_set(void *data, u64 val)
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{
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*(unsigned long *)data =
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min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
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debugfs_stacktrace_depth_set, "%llu\n");
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static struct dentry *debugfs_create_stacktrace_depth(
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const char *name, umode_t mode,
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struct dentry *parent, unsigned long *value)
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{
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return debugfs_create_file(name, mode, parent, value,
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&fops_stacktrace_depth);
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}
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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struct dentry *fault_create_debugfs_attr(const char *name,
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struct dentry *parent, struct fault_attr *attr)
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{
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umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
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struct dentry *dir;
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dir = debugfs_create_dir(name, parent);
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if (!dir)
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return ERR_PTR(-ENOMEM);
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if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
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goto fail;
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if (!debugfs_create_ul("interval", mode, dir, &attr->interval))
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goto fail;
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if (!debugfs_create_atomic_t("times", mode, dir, &attr->times))
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goto fail;
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if (!debugfs_create_atomic_t("space", mode, dir, &attr->space))
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goto fail;
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if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
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goto fail;
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if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
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&attr->ratelimit_state.interval))
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goto fail;
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if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
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&attr->ratelimit_state.burst))
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goto fail;
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if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
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goto fail;
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
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&attr->stacktrace_depth))
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goto fail;
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if (!debugfs_create_ul("require-start", mode, dir,
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&attr->require_start))
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goto fail;
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if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end))
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goto fail;
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if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start))
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goto fail;
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if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end))
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goto fail;
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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attr->dname = dget(dir);
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return dir;
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fail:
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debugfs_remove_recursive(dir);
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return ERR_PTR(-ENOMEM);
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}
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EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
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#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
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