| 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. |
| |
| * CPU notifier |
| * PM notifier |
| * Memory hotplug notifier |
| * powerpc pSeries reconfig notifier |
| |
| CPU notifier error injection module |
| ----------------------------------- |
| This feature can be used to test the error handling of the CPU notifiers by |
| injecting artificial errors to CPU notifier chain callbacks. |
| |
| If the notifier call chain should be failed with some events notified, write |
| the error code to debugfs interface |
| /sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error |
| |
| Possible CPU notifier events to be failed are: |
| |
| * CPU_UP_PREPARE |
| * CPU_UP_PREPARE_FROZEN |
| * CPU_DOWN_PREPARE |
| * CPU_DOWN_PREPARE_FROZEN |
| |
| Example1: Inject CPU offline error (-1 == -EPERM) |
| |
| # cd /sys/kernel/debug/notifier-error-inject/cpu |
| # echo -1 > actions/CPU_DOWN_PREPARE/error |
| # echo 0 > /sys/devices/system/cpu/cpu1/online |
| bash: echo: write error: Operation not permitted |
| |
| Example2: inject CPU online error (-2 == -ENOENT) |
| |
| # echo -2 > actions/CPU_UP_PREPARE/error |
| # echo 1 > /sys/devices/system/cpu/cpu1/online |
| bash: echo: write error: No such file or directory |
| |
| 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 |
| |
| 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. |
