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![Akinobu Mita](/assets/img/avatar_default.png)
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>
437 lines
11 KiB
C
437 lines
11 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 || (found && !attr->reject_start && !attr->reject_end))
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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_ex(struct fault_attr *attr, ssize_t size, int flags)
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{
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bool stack_checked = false;
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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 (!fail_stacktrace(attr))
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return false;
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stack_checked = true;
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fail_nth--;
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WRITE_ONCE(current->fail_nth, fail_nth);
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if (!fail_nth)
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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 (!stack_checked && !fail_stacktrace(attr))
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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 <= get_random_u32_below(100))
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return false;
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fail:
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if (!(flags & FAULT_NOWARN))
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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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bool should_fail(struct fault_attr *attr, ssize_t size)
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{
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return should_fail_ex(attr, size, 0);
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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 void 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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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 void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
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struct dentry *parent,
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unsigned long *value)
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{
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debugfs_create_file(name, mode, parent, value, &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 (IS_ERR(dir))
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return dir;
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debugfs_create_ul("probability", mode, dir, &attr->probability);
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debugfs_create_ul("interval", mode, dir, &attr->interval);
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debugfs_create_atomic_t("times", mode, dir, &attr->times);
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debugfs_create_atomic_t("space", mode, dir, &attr->space);
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debugfs_create_ul("verbose", mode, dir, &attr->verbose);
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debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
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&attr->ratelimit_state.interval);
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debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
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&attr->ratelimit_state.burst);
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debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
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&attr->stacktrace_depth);
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debugfs_create_xul("require-start", mode, dir, &attr->require_start);
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debugfs_create_xul("require-end", mode, dir, &attr->require_end);
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debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
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debugfs_create_xul("reject-end", mode, dir, &attr->reject_end);
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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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}
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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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#ifdef CONFIG_FAULT_INJECTION_CONFIGFS
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/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */
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static ssize_t fault_uint_attr_show(unsigned int val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%u\n", val);
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}
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static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%lu\n", val);
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}
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static ssize_t fault_bool_attr_show(bool val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%u\n", val);
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}
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static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page)
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{
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return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val));
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}
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static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count)
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{
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unsigned int tmp;
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int result;
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result = kstrtouint(page, 0, &tmp);
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if (result < 0)
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return result;
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*val = tmp;
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return count;
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}
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static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count)
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{
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int result;
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unsigned long tmp;
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result = kstrtoul(page, 0, &tmp);
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if (result < 0)
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return result;
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*val = tmp;
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return count;
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}
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static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count)
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{
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bool tmp;
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int result;
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result = kstrtobool(page, &tmp);
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if (result < 0)
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return result;
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*val = tmp;
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return count;
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}
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static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count)
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{
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int tmp;
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int result;
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result = kstrtoint(page, 0, &tmp);
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if (result < 0)
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return result;
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atomic_set(val, tmp);
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return count;
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}
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#define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name) \
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static struct configfs_attribute _pfx##attr_##_name = { \
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.ca_name = _attr_name, \
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.ca_mode = 0644, \
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.ca_owner = THIS_MODULE, \
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.show = _pfx##_name##_show, \
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.store = _pfx##_name##_store, \
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}
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static struct fault_config *to_fault_config(struct config_item *item)
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{
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return container_of(to_config_group(item), struct fault_config, group);
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}
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#define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE) \
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static ssize_t fault_##NAME##_show(struct config_item *item, char *page) \
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{ \
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return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page); \
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} \
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static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count) \
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{ \
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struct fault_config *config = to_fault_config(item); \
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return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count); \
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} \
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CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME)
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#define FAULT_CONFIGFS_ATTR(NAME, TYPE) \
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FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE)
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FAULT_CONFIGFS_ATTR(probability, ulong);
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FAULT_CONFIGFS_ATTR(interval, ulong);
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FAULT_CONFIGFS_ATTR(times, atomic_t);
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FAULT_CONFIGFS_ATTR(space, atomic_t);
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FAULT_CONFIGFS_ATTR(verbose, ulong);
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FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
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ratelimit_state.interval, uint);
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FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
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ratelimit_state.burst, uint);
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FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page)
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{
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return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page);
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}
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static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page,
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size_t count)
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{
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int result;
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unsigned long tmp;
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result = kstrtoul(page, 0, &tmp);
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if (result < 0)
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return result;
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to_fault_config(item)->attr.stacktrace_depth =
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min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH);
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return count;
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}
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CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");
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static ssize_t fault_xul_attr_show(unsigned long val, char *page)
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{
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return snprintf(page, PAGE_SIZE,
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sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val);
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}
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static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count)
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{
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return fault_ulong_attr_store(val, page, count);
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}
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FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
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FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
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FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
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FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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static struct configfs_attribute *fault_config_attrs[] = {
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&fault_attr_probability,
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&fault_attr_interval,
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&fault_attr_times,
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&fault_attr_space,
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&fault_attr_verbose,
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&fault_attr_ratelimit_interval,
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&fault_attr_ratelimit_burst,
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&fault_attr_task_filter,
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#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
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&fault_attr_stacktrace_depth,
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&fault_attr_require_start,
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&fault_attr_require_end,
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&fault_attr_reject_start,
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&fault_attr_reject_end,
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#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
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NULL,
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};
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static const struct config_item_type fault_config_type = {
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.ct_attrs = fault_config_attrs,
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.ct_owner = THIS_MODULE,
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};
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void fault_config_init(struct fault_config *config, const char *name)
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{
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config_group_init_type_name(&config->group, name, &fault_config_type);
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}
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EXPORT_SYMBOL_GPL(fault_config_init);
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#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */
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