net: add support for netdev notifier error injection
This module allows to insert errors in some of netdevice's notifier
events. All network drivers use these notifiers to signal various events
and to check if they are allowed, e.g. PRECHANGEMTU and CHANGEMTU
afterwards. Until recently I had to run failure tests by injecting
a custom module, but now this infrastructure makes it trivial to test
these failure paths. Some of the recent bugs I fixed were found using
this module.
Here's an example:
$ cd /sys/kernel/debug/notifier-error-inject/netdev
$ echo -22 > actions/NETDEV_CHANGEMTU/error
$ ip link set eth0 mtu 1024
RTNETLINK answers: Invalid argument
CC: Akinobu Mita <akinobu.mita@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: netdev <netdev@vger.kernel.org>
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/lib/netdev-notifier-error-inject.c b/lib/netdev-notifier-error-inject.c
new file mode 100644
index 0000000..b2b8566
--- /dev/null
+++ b/lib/netdev-notifier-error-inject.c
@@ -0,0 +1,54 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+
+#include "notifier-error-inject.h"
+
+static int priority;
+module_param(priority, int, 0);
+MODULE_PARM_DESC(priority, "specify netdevice notifier priority");
+
+static struct notifier_err_inject netdev_notifier_err_inject = {
+ .actions = {
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_REGISTER) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_CHANGEMTU) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_CHANGENAME) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRE_UP) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRE_TYPE_CHANGE) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_POST_INIT) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRECHANGEMTU) },
+ { NOTIFIER_ERR_INJECT_ACTION(NETDEV_PRECHANGEUPPER) },
+ {}
+ }
+};
+
+static struct dentry *dir;
+
+static int netdev_err_inject_init(void)
+{
+ int err;
+
+ dir = notifier_err_inject_init("netdev", notifier_err_inject_dir,
+ &netdev_notifier_err_inject, priority);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ err = register_netdevice_notifier(&netdev_notifier_err_inject.nb);
+ if (err)
+ debugfs_remove_recursive(dir);
+
+ return err;
+}
+
+static void netdev_err_inject_exit(void)
+{
+ unregister_netdevice_notifier(&netdev_notifier_err_inject.nb);
+ debugfs_remove_recursive(dir);
+}
+
+module_init(netdev_err_inject_init);
+module_exit(netdev_err_inject_exit);
+
+MODULE_DESCRIPTION("Netdevice notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nikolay Aleksandrov <razor@blackwall.org>");