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![Christoph Hellwig](/assets/img/avatar_default.png)
Sometimes simple attributes might need to return an error, e.g. for acquiring a mutex interruptibly. In fact we have that situation in spufs already which is the original user of the simple attributes. This patch merged the temporarily forked attributes in spufs back into the main ones and allows to return errors. [akpm@linux-foundation.org: build fix] Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: <stefano.brivio@polimi.it> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg KH <greg@kroah.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
315 lines
7.9 KiB
C
315 lines
7.9 KiB
C
#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/stat.h>
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/unwind.h>
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#include <linux/stacktrace.h>
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#include <linux/kallsyms.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 __init 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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static void fail_dump(struct fault_attr *attr)
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{
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if (attr->verbose > 0)
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printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
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if (attr->verbose > 1)
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dump_stack();
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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_interrupt() && 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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struct stack_trace trace;
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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;
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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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trace.nr_entries = 0;
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trace.entries = entries;
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trace.max_entries = depth;
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trace.skip = 1;
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save_stack_trace(&trace);
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for (n = 0; n < trace.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 (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 <= random32() % 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_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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#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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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
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{
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*(unsigned long *)data =
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val < MAX_STACK_TRACE_DEPTH ?
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val : MAX_STACK_TRACE_DEPTH;
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return 0;
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}
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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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, mode_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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DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
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debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
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static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
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const char *name, mode_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_ul_MAX_STACK_TRACE_DEPTH);
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}
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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static int debugfs_atomic_t_set(void *data, u64 val)
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{
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atomic_set((atomic_t *)data, val);
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return 0;
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}
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static int debugfs_atomic_t_get(void *data, u64 *val)
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{
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*val = atomic_read((atomic_t *)data);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
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debugfs_atomic_t_set, "%lld\n");
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static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
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struct dentry *parent, atomic_t *value)
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{
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return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
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}
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void cleanup_fault_attr_dentries(struct fault_attr *attr)
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{
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debugfs_remove(attr->dentries.probability_file);
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attr->dentries.probability_file = NULL;
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debugfs_remove(attr->dentries.interval_file);
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attr->dentries.interval_file = NULL;
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debugfs_remove(attr->dentries.times_file);
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attr->dentries.times_file = NULL;
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debugfs_remove(attr->dentries.space_file);
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attr->dentries.space_file = NULL;
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debugfs_remove(attr->dentries.verbose_file);
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attr->dentries.verbose_file = NULL;
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debugfs_remove(attr->dentries.task_filter_file);
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attr->dentries.task_filter_file = NULL;
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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debugfs_remove(attr->dentries.stacktrace_depth_file);
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attr->dentries.stacktrace_depth_file = NULL;
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debugfs_remove(attr->dentries.require_start_file);
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attr->dentries.require_start_file = NULL;
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debugfs_remove(attr->dentries.require_end_file);
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attr->dentries.require_end_file = NULL;
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debugfs_remove(attr->dentries.reject_start_file);
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attr->dentries.reject_start_file = NULL;
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debugfs_remove(attr->dentries.reject_end_file);
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attr->dentries.reject_end_file = NULL;
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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if (attr->dentries.dir)
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WARN_ON(!simple_empty(attr->dentries.dir));
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debugfs_remove(attr->dentries.dir);
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attr->dentries.dir = NULL;
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}
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int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
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{
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mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
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struct dentry *dir;
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memset(&attr->dentries, 0, sizeof(attr->dentries));
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dir = debugfs_create_dir(name, NULL);
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if (!dir)
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goto fail;
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attr->dentries.dir = dir;
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attr->dentries.probability_file =
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debugfs_create_ul("probability", mode, dir, &attr->probability);
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attr->dentries.interval_file =
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debugfs_create_ul("interval", mode, dir, &attr->interval);
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attr->dentries.times_file =
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debugfs_create_atomic_t("times", mode, dir, &attr->times);
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attr->dentries.space_file =
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debugfs_create_atomic_t("space", mode, dir, &attr->space);
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attr->dentries.verbose_file =
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debugfs_create_ul("verbose", mode, dir, &attr->verbose);
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attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
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mode, dir, &attr->task_filter);
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if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
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!attr->dentries.times_file || !attr->dentries.space_file ||
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!attr->dentries.verbose_file || !attr->dentries.task_filter_file)
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goto fail;
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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attr->dentries.stacktrace_depth_file =
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debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
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"stacktrace-depth", mode, dir, &attr->stacktrace_depth);
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attr->dentries.require_start_file =
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debugfs_create_ul("require-start", mode, dir, &attr->require_start);
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attr->dentries.require_end_file =
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debugfs_create_ul("require-end", mode, dir, &attr->require_end);
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attr->dentries.reject_start_file =
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debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
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attr->dentries.reject_end_file =
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debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
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if (!attr->dentries.stacktrace_depth_file ||
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!attr->dentries.require_start_file ||
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!attr->dentries.require_end_file ||
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!attr->dentries.reject_start_file ||
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!attr->dentries.reject_end_file)
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goto fail;
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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return 0;
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fail:
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cleanup_fault_attr_dentries(attr);
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return -ENOMEM;
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}
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#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
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