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100 lines
3.3 KiB
Plaintext
100 lines
3.3 KiB
Plaintext
Notifier error injection
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========================
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Notifier error injection provides the ability to inject artificial errors to
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specified notifier chain callbacks. It is useful to test the error handling of
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notifier call chain failures which is rarely executed. There are kernel
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modules that can be used to test the following notifiers.
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* CPU notifier
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* PM notifier
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* Memory hotplug notifier
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* powerpc pSeries reconfig notifier
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CPU notifier error injection module
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-----------------------------------
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This feature can be used to test the error handling of the CPU notifiers by
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injecting artificial errors to CPU notifier chain callbacks.
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If the notifier call chain should be failed with some events notified, write
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the error code to debugfs interface
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/sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error
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Possible CPU notifier events to be failed are:
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* CPU_UP_PREPARE
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* CPU_UP_PREPARE_FROZEN
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* CPU_DOWN_PREPARE
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* CPU_DOWN_PREPARE_FROZEN
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Example1: Inject CPU offline error (-1 == -EPERM)
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# cd /sys/kernel/debug/notifier-error-inject/cpu
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# echo -1 > actions/CPU_DOWN_PREPARE/error
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# echo 0 > /sys/devices/system/cpu/cpu1/online
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bash: echo: write error: Operation not permitted
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Example2: inject CPU online error (-2 == -ENOENT)
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# echo -2 > actions/CPU_UP_PREPARE/error
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# echo 1 > /sys/devices/system/cpu/cpu1/online
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bash: echo: write error: No such file or directory
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PM notifier error injection module
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----------------------------------
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This feature is controlled through debugfs interface
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/sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error
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Possible PM notifier events to be failed are:
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* PM_HIBERNATION_PREPARE
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* PM_SUSPEND_PREPARE
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* PM_RESTORE_PREPARE
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Example: Inject PM suspend error (-12 = -ENOMEM)
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# cd /sys/kernel/debug/notifier-error-inject/pm/
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# echo -12 > actions/PM_SUSPEND_PREPARE/error
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# echo mem > /sys/power/state
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bash: echo: write error: Cannot allocate memory
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Memory hotplug notifier error injection module
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----------------------------------------------
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This feature is controlled through debugfs interface
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/sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error
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Possible memory notifier events to be failed are:
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* MEM_GOING_ONLINE
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* MEM_GOING_OFFLINE
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Example: Inject memory hotplug offline error (-12 == -ENOMEM)
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# cd /sys/kernel/debug/notifier-error-inject/memory
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# echo -12 > actions/MEM_GOING_OFFLINE/error
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# echo offline > /sys/devices/system/memory/memoryXXX/state
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bash: echo: write error: Cannot allocate memory
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powerpc pSeries reconfig notifier error injection module
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--------------------------------------------------------
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This feature is controlled through debugfs interface
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/sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error
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Possible pSeries reconfig notifier events to be failed are:
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* PSERIES_RECONFIG_ADD
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* PSERIES_RECONFIG_REMOVE
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* PSERIES_DRCONF_MEM_ADD
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* PSERIES_DRCONF_MEM_REMOVE
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For more usage examples
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-----------------------
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There are tools/testing/selftests using the notifier error injection features
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for CPU and memory notifiers.
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* tools/testing/selftests/cpu-hotplug/on-off-test.sh
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* tools/testing/selftests/memory-hotplug/on-off-test.sh
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These scripts first do simple online and offline tests and then do fault
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injection tests if notifier error injection module is available.
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