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/Documentation/fault-injection/notifier-error-inject.txt b/Documentation/fault-injection/notifier-error-inject.txt
index 09adabe..71e638a 100644
--- a/Documentation/fault-injection/notifier-error-inject.txt
+++ b/Documentation/fault-injection/notifier-error-inject.txt
@@ -10,6 +10,7 @@
* PM notifier
* Memory hotplug notifier
* powerpc pSeries reconfig notifier
+ * Netdevice notifier
CPU notifier error injection module
-----------------------------------
@@ -87,6 +88,29 @@
* PSERIES_DRCONF_MEM_ADD
* PSERIES_DRCONF_MEM_REMOVE
+Netdevice notifier error injection module
+----------------------------------------------
+This feature is controlled through debugfs interface
+/sys/kernel/debug/notifier-error-inject/netdev/actions/<notifier event>/error
+
+Netdevice notifier events which can be failed are:
+
+ * NETDEV_REGISTER
+ * NETDEV_CHANGEMTU
+ * NETDEV_CHANGENAME
+ * NETDEV_PRE_UP
+ * NETDEV_PRE_TYPE_CHANGE
+ * NETDEV_POST_INIT
+ * NETDEV_PRECHANGEMTU
+ * NETDEV_PRECHANGEUPPER
+
+Example: Inject netdevice mtu change error (-22 == -EINVAL)
+
+ # cd /sys/kernel/debug/notifier-error-inject/netdev
+ # echo -22 > actions/NETDEV_CHANGEMTU/error
+ # ip link set eth0 mtu 1024
+ RTNETLINK answers: Invalid argument
+
For more usage examples
-----------------------
There are tools/testing/selftests using the notifier error injection features
