LXR linux/lib/notifier-error-inject.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/module.h>
   3
   4#include "notifier-error-inject.h"
   5
   6static int debugfs_errno_set(void *data, u64 val)
   7{
   8        *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
   9        return 0;
  10}
  11
  12static int debugfs_errno_get(void *data, u64 *val)
  13{
  14        *val = *(int *)data;
  15        return 0;
  16}
  17
  18DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
  19                        "%lld\n");
  20
  21static struct dentry *debugfs_create_errno(const char *name, umode_t mode,
  22                                struct dentry *parent, int *value)
  23{
  24        return debugfs_create_file(name, mode, parent, value, &fops_errno);
  25}
  26
  27static int notifier_err_inject_callback(struct notifier_block *nb,
  28                                unsigned long val, void *p)
  29{
  30        int err = 0;
  31        struct notifier_err_inject *err_inject =
  32                container_of(nb, struct notifier_err_inject, nb);
  33        struct notifier_err_inject_action *action;
  34
  35        for (action = err_inject->actions; action->name; action++) {
  36                if (action->val == val) {
  37                        err = action->error;
  38                        break;
  39                }
  40        }
  41        if (err)
  42                pr_info("Injecting error (%d) to %s\n", err, action->name);
  43
  44        return notifier_from_errno(err);
  45}
  46
  47struct dentry *notifier_err_inject_dir;
  48EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
  49
  50struct dentry *notifier_err_inject_init(const char *name, struct dentry *parent,
  51                        struct notifier_err_inject *err_inject, int priority)
  52{
  53        struct notifier_err_inject_action *action;
  54        umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
  55        struct dentry *dir;
  56        struct dentry *actions_dir;
  57
  58        err_inject->nb.notifier_call = notifier_err_inject_callback;
  59        err_inject->nb.priority = priority;
  60
  61        dir = debugfs_create_dir(name, parent);
  62
  63        actions_dir = debugfs_create_dir("actions", dir);
  64
  65        for (action = err_inject->actions; action->name; action++) {
  66                struct dentry *action_dir;
  67
  68                action_dir = debugfs_create_dir(action->name, actions_dir);
  69
  70                /*
  71                 * Create debugfs r/w file containing action->error. If
  72                 * notifier call chain is called with action->val, it will
  73                 * fail with the error code
  74                 */
  75                debugfs_create_errno("error", mode, action_dir, &action->error);
  76        }
  77        return dir;
  78}
  79EXPORT_SYMBOL_GPL(notifier_err_inject_init);
  80
  81static int __init err_inject_init(void)
  82{
  83        notifier_err_inject_dir =
  84                debugfs_create_dir("notifier-error-inject", NULL);
  85
  86        if (!notifier_err_inject_dir)
  87                return -ENOMEM;
  88
  89        return 0;
  90}
  91
  92static void __exit err_inject_exit(void)
  93{
  94        debugfs_remove_recursive(notifier_err_inject_dir);
  95}
  96
  97module_init(err_inject_init);
  98module_exit(err_inject_exit);
  99
 100MODULE_DESCRIPTION("Notifier error injection module");
 101MODULE_LICENSE("GPL");
 102MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 103