1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 
4 #include "notifier-error-inject.h"
5 
debugfs_errno_set(void * data,u64 val)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 
debugfs_errno_get(void * data,u64 * val)12 static int debugfs_errno_get(void *data, u64 *val)
13 {
14 	*val = *(int *)data;
15 	return 0;
16 }
17 
18 DEFINE_SIMPLE_ATTRIBUTE_SIGNED(fops_errno, debugfs_errno_get, debugfs_errno_set,
19 			"%lld\n");
20 
debugfs_create_errno(const char * name,umode_t mode,struct dentry * parent,int * value)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 
notifier_err_inject_callback(struct notifier_block * nb,unsigned long val,void * p)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 
notifier_err_inject_init(const char * name,struct dentry * parent,struct notifier_err_inject * err_inject,int priority)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 
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 }
79 EXPORT_SYMBOL_GPL(notifier_err_inject_init);
80 
err_inject_init(void)81 static 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 
err_inject_exit(void)92 static void __exit err_inject_exit(void)
93 {
94 	debugfs_remove_recursive(notifier_err_inject_dir);
95 }
96 
97 module_init(err_inject_init);
98 module_exit(err_inject_exit);
99 
100 MODULE_DESCRIPTION("Notifier error injection module");
101 MODULE_LICENSE("GPL");
102 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
103