Documentation / fault-injection / notifier-error-inject.txt
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Based on kernel version 3.9. Page generated on 2013-05-02 23:05 EST.
1 Notifier error injection 2 ======================== 3 4 Notifier error injection provides the ability to inject artificial errors to 5 specified notifier chain callbacks. It is useful to test the error handling of 6 notifier call chain failures which is rarely executed. There are kernel 7 modules that can be used to test the following notifiers. 8 9 * CPU notifier 10 * PM notifier 11 * Memory hotplug notifier 12 * powerpc pSeries reconfig notifier 13 14 CPU notifier error injection module 15 ----------------------------------- 16 This feature can be used to test the error handling of the CPU notifiers by 17 injecting artificial errors to CPU notifier chain callbacks. 18 19 If the notifier call chain should be failed with some events notified, write 20 the error code to debugfs interface 21 /sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error 22 23 Possible CPU notifier events to be failed are: 24 25 * CPU_UP_PREPARE 26 * CPU_UP_PREPARE_FROZEN 27 * CPU_DOWN_PREPARE 28 * CPU_DOWN_PREPARE_FROZEN 29 30 Example1: Inject CPU offline error (-1 == -EPERM) 31 32 # cd /sys/kernel/debug/notifier-error-inject/cpu 33 # echo -1 > actions/CPU_DOWN_PREPARE/error 34 # echo 0 > /sys/devices/system/cpu/cpu1/online 35 bash: echo: write error: Operation not permitted 36 37 Example2: inject CPU online error (-2 == -ENOENT) 38 39 # echo -2 > actions/CPU_UP_PREPARE/error 40 # echo 1 > /sys/devices/system/cpu/cpu1/online 41 bash: echo: write error: No such file or directory 42 43 PM notifier error injection module 44 ---------------------------------- 45 This feature is controlled through debugfs interface 46 /sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error 47 48 Possible PM notifier events to be failed are: 49 50 * PM_HIBERNATION_PREPARE 51 * PM_SUSPEND_PREPARE 52 * PM_RESTORE_PREPARE 53 54 Example: Inject PM suspend error (-12 = -ENOMEM) 55 56 # cd /sys/kernel/debug/notifier-error-inject/pm/ 57 # echo -12 > actions/PM_SUSPEND_PREPARE/error 58 # echo mem > /sys/power/state 59 bash: echo: write error: Cannot allocate memory 60 61 Memory hotplug notifier error injection module 62 ---------------------------------------------- 63 This feature is controlled through debugfs interface 64 /sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error 65 66 Possible memory notifier events to be failed are: 67 68 * MEM_GOING_ONLINE 69 * MEM_GOING_OFFLINE 70 71 Example: Inject memory hotplug offline error (-12 == -ENOMEM) 72 73 # cd /sys/kernel/debug/notifier-error-inject/memory 74 # echo -12 > actions/MEM_GOING_OFFLINE/error 75 # echo offline > /sys/devices/system/memory/memoryXXX/state 76 bash: echo: write error: Cannot allocate memory 77 78 powerpc pSeries reconfig notifier error injection module 79 -------------------------------------------------------- 80 This feature is controlled through debugfs interface 81 /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error 82 83 Possible pSeries reconfig notifier events to be failed are: 84 85 * PSERIES_RECONFIG_ADD 86 * PSERIES_RECONFIG_REMOVE 87 * PSERIES_DRCONF_MEM_ADD 88 * PSERIES_DRCONF_MEM_REMOVE 89 90 For more usage examples 91 ----------------------- 92 There are tools/testing/selftests using the notifier error injection features 93 for CPU and memory notifiers. 94 95 * tools/testing/selftests/cpu-hotplug/on-off-test.sh 96 * tools/testing/selftests/memory-hotplug/on-off-test.sh 97 98 These scripts first do simple online and offline tests and then do fault 99 injection tests if notifier error injection module is available.
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