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/Kconfig.debug b/lib/Kconfig.debug
index 8c15b29..0d76ecc 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1484,6 +1484,29 @@
If unsure, say N.
+config NETDEV_NOTIFIER_ERROR_INJECT
+ tristate "Netdev notifier error injection module"
+ depends on NET && NOTIFIER_ERROR_INJECTION
+ help
+ This option provides the ability to inject artificial errors to
+ netdevice notifier chain callbacks. It is controlled through debugfs
+ interface /sys/kernel/debug/notifier-error-inject/netdev
+
+ If the notifier call chain should be failed with some events
+ notified, write the error code to "actions/<notifier event>/error".
+
+ 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
+
+ To compile this code as a module, choose M here: the module will
+ be called netdev-notifier-error-inject.
+
+ If unsure, say N.
+
config FAULT_INJECTION
bool "Fault-injection framework"
depends on DEBUG_KERNEL