| Notifier error injection |
| ======================== |
| |
| Notifier error injection provides the ability to inject artificial errors to |
| specified notifier chain callbacks. It is useful to test the error handling of |
| notifier call chain failures which is rarely executed. There are kernel |
| modules that can be used to test the following notifiers. |
| |
| * PM notifier |
| * Memory hotplug notifier |
| * powerpc pSeries reconfig notifier |
| * Netdevice notifier |
| |
| PM notifier error injection module |
| ---------------------------------- |
| This feature is controlled through debugfs interface |
| /sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error |
| |
| Possible PM notifier events to be failed are: |
| |
| * PM_HIBERNATION_PREPARE |
| * PM_SUSPEND_PREPARE |
| * PM_RESTORE_PREPARE |
| |
| Example: Inject PM suspend error (-12 = -ENOMEM) |
| |
| # cd /sys/kernel/debug/notifier-error-inject/pm/ |
| # echo -12 > actions/PM_SUSPEND_PREPARE/error |
| # echo mem > /sys/power/state |
| bash: echo: write error: Cannot allocate memory |
| |
| Memory hotplug notifier error injection module |
| ---------------------------------------------- |
| This feature is controlled through debugfs interface |
| /sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error |
| |
| Possible memory notifier events to be failed are: |
| |
| * MEM_GOING_ONLINE |
| * MEM_GOING_OFFLINE |
| |
| Example: Inject memory hotplug offline error (-12 == -ENOMEM) |
| |
| # cd /sys/kernel/debug/notifier-error-inject/memory |
| # echo -12 > actions/MEM_GOING_OFFLINE/error |
| # echo offline > /sys/devices/system/memory/memoryXXX/state |
| bash: echo: write error: Cannot allocate memory |
| |
| powerpc pSeries reconfig notifier error injection module |
| -------------------------------------------------------- |
| This feature is controlled through debugfs interface |
| /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error |
| |
| Possible pSeries reconfig notifier events to be failed are: |
| |
| * PSERIES_RECONFIG_ADD |
| * PSERIES_RECONFIG_REMOVE |
| * 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 |
| * NETDEV_CHANGEUPPER |
| |
| 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 |
| for CPU and memory notifiers. |
| |
| * tools/testing/selftests/cpu-hotplug/on-off-test.sh |
| * tools/testing/selftests/memory-hotplug/on-off-test.sh |
| |
| These scripts first do simple online and offline tests and then do fault |
| injection tests if notifier error injection module is available. |