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
   6 static int debugfs_errno_set(void *data, u64 val)
   7 {
   8         *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
   9         return 0;
  10 }
  11
  12 static int debugfs_errno_get(void *data, u64 *val)
  13 {
  14         *val = *(int *)data;
  15         return 0;
  16 }
  17
  18 DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
  19                         "%lld\n");
  20
  21 static 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
  27 static 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
  47 struct dentry *notifier_err_inject_dir;
  48 EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
  49
  50 struct 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         if (!dir)
  63                 return ERR_PTR(-ENOMEM);
  64
  65         actions_dir = debugfs_create_dir("actions", dir);
  66         if (!actions_dir)
  67                 goto fail;
  68
  69         for (action = err_inject->actions; action->name; action++) {
  70                 struct dentry *action_dir;
  71
  72                 action_dir = debugfs_create_dir(action->name, actions_dir);
  73                 if (!action_dir)
  74                         goto fail;
  75
  76                 /*
  77                  * Create debugfs r/w file containing action->error. If
  78                  * notifier call chain is called with action->val, it will
  79                  * fail with the error code
  80                  */
  81                 if (!debugfs_create_errno("error", mode, action_dir,
  82                                         &action->error))
  83                         goto fail;
  84         }
  85         return dir;
  86 fail:
  87         debugfs_remove_recursive(dir);
  88         return ERR_PTR(-ENOMEM);
  89 }
  90 EXPORT_SYMBOL_GPL(notifier_err_inject_init);
  91
  92 static int __init err_inject_init(void)
  93 {
  94         notifier_err_inject_dir =
  95                 debugfs_create_dir("notifier-error-inject", NULL);
  96
  97         if (!notifier_err_inject_dir)
  98                 return -ENOMEM;
  99
 100         return 0;
 101 }
 102
 103 static void __exit err_inject_exit(void)
 104 {
 105         debugfs_remove_recursive(notifier_err_inject_dir);
 106 }
 107
 108 module_init(err_inject_init);
 109 module_exit(err_inject_exit);
 110
 111 MODULE_DESCRIPTION("Notifier error injection module");
 112 MODULE_LICENSE("GPL");
 113 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");