lib/notifier-error-inject.c

   1 #include <linux/module.h>
   2
   3 #include "notifier-error-inject.h"
   4
   5 static int debugfs_errno_set(void *data, u64 val)
   6 {
   7         *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
   8         return 0;
   9 }
  10
  11 static int debugfs_errno_get(void *data, u64 *val)
  12 {
  13         *val = *(int *)data;
  14         return 0;
  15 }
  16
  17 DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
  18                         "%lld\n");
  19
  20 static struct dentry *debugfs_create_errno(const char *name, umode_t mode,
  21                                 struct dentry *parent, int *value)
  22 {
  23         return debugfs_create_file(name, mode, parent, value, &fops_errno);
  24 }
  25
  26 static int notifier_err_inject_callback(struct notifier_block *nb,
  27                                 unsigned long val, void *p)
  28 {
  29         int err = 0;
  30         struct notifier_err_inject *err_inject =
  31                 container_of(nb, struct notifier_err_inject, nb);
  32         struct notifier_err_inject_action *action;
  33
  34         for (action = err_inject->actions; action->name; action++) {
  35                 if (action->val == val) {
  36                         err = action->error;
  37                         break;
  38                 }
  39         }
  40         if (err)
  41                 pr_info("Injecting error (%d) to %s\n", err, action->name);
  42
  43         return notifier_from_errno(err);
  44 }
  45
  46 struct dentry *notifier_err_inject_dir;
  47 EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
  48
  49 struct dentry *notifier_err_inject_init(const char *name, struct dentry *parent,
  50                         struct notifier_err_inject *err_inject, int priority)
  51 {
  52         struct notifier_err_inject_action *action;
  53         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
  54         struct dentry *dir;
  55         struct dentry *actions_dir;
  56
  57         err_inject->nb.notifier_call = notifier_err_inject_callback;
  58         err_inject->nb.priority = priority;
  59
  60         dir = debugfs_create_dir(name, parent);
  61         if (!dir)
  62                 return ERR_PTR(-ENOMEM);
  63
  64         actions_dir = debugfs_create_dir("actions", dir);
  65         if (!actions_dir)
  66                 goto fail;
  67
  68         for (action = err_inject->actions; action->name; action++) {
  69                 struct dentry *action_dir;
  70
  71                 action_dir = debugfs_create_dir(action->name, actions_dir);
  72                 if (!action_dir)
  73                         goto fail;
  74
  75                 /*
  76                  * Create debugfs r/w file containing action->error. If
  77                  * notifier call chain is called with action->val, it will
  78                  * fail with the error code
  79                  */
  80                 if (!debugfs_create_errno("error", mode, action_dir,
  81                                         &action->error))
  82                         goto fail;
  83         }
  84         return dir;
  85 fail:
  86         debugfs_remove_recursive(dir);
  87         return ERR_PTR(-ENOMEM);
  88 }
  89 EXPORT_SYMBOL_GPL(notifier_err_inject_init);
  90
  91 static int __init err_inject_init(void)
  92 {
  93         notifier_err_inject_dir =
  94                 debugfs_create_dir("notifier-error-inject", NULL);
  95
  96         if (!notifier_err_inject_dir)
  97                 return -ENOMEM;
  98
  99         return 0;
 100 }
 101
 102 static void __exit err_inject_exit(void)
 103 {
 104         debugfs_remove_recursive(notifier_err_inject_dir);
 105 }
 106
 107 module_init(err_inject_init);
 108 module_exit(err_inject_exit);
 109
 110 MODULE_DESCRIPTION("Notifier error injection module");
 111 MODULE_LICENSE("GPL");
 112 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");