linux/lib/notifier-error-inject.c
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   1#include <linux/module.h>
   2
   3#include "notifier-error-inject.h"
   4
   5static int debugfs_errno_set(void *data, u64 val)
   6{
   7        *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
   8        return 0;
   9}
  10
  11static int debugfs_errno_get(void *data, u64 *val)
  12{
  13        *val = *(int *)data;
  14        return 0;
  15}
  16
  17DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
  18                        "%lld\n");
  19
  20static struct dentry *debugfs_create_errno(const char *name, mode_t mode,
  21                                struct dentry *parent, int *value)
  22{
  23        return debugfs_create_file(name, mode, parent, value, &fops_errno);
  24}
  25
  26static 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
  46struct dentry *notifier_err_inject_dir;
  47EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
  48
  49struct 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        mode_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;
  85fail:
  86        debugfs_remove_recursive(dir);
  87        return ERR_PTR(-ENOMEM);
  88}
  89EXPORT_SYMBOL_GPL(notifier_err_inject_init);
  90
  91static 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
 102static void __exit err_inject_exit(void)
 103{
 104        debugfs_remove_recursive(notifier_err_inject_dir);
 105}
 106
 107module_init(err_inject_init);
 108module_exit(err_inject_exit);
 109
 110MODULE_DESCRIPTION("Notifier error injection module");
 111MODULE_LICENSE("GPL");
 112MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 113
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