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Linux/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>");
113 

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