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Commit 02fff96a authored by Nikolay Aleksandrov's avatar Nikolay Aleksandrov Committed by David S. Miller
Browse files

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: default avatarNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 27a70af3

Documentation/fault-injection/notifier-error-inject.txt

+24 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ modules that can be used to test the following notifiers. 
 * PM notifier

 * Memory hotplug notifier

 * powerpc pSeries reconfig notifier

 * Netdevice notifier



CPU notifier error injection module

-----------------------------------
@@ -87,6 +88,29 @@ Possible pSeries reconfig notifier events to be failed are: 
 * 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

lib/Kconfig.debug

+23 −0
Original line number Diff line number Diff line
@@ -1484,6 +1484,29 @@ config OF_RECONFIG_NOTIFIER_ERROR_INJECT 


	  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

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -120,6 +120,7 @@ obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o 
obj-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o

obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o

obj-$(CONFIG_PM_NOTIFIER_ERROR_INJECT) += pm-notifier-error-inject.o

obj-$(CONFIG_NETDEV_NOTIFIER_ERROR_INJECT) += netdev-notifier-error-inject.o

obj-$(CONFIG_MEMORY_NOTIFIER_ERROR_INJECT) += memory-notifier-error-inject.o

obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \

	of-reconfig-notifier-error-inject.o

lib/netdev-notifier-error-inject.c

0 → 100644
+54 −0
Original line number Diff line number Diff line 
#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>");