projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 8d438288 AM |
1 | Notifier error injection |
| 2 | ======================== | |
| 3 | ||
| 4e79162a | 4 | Notifier error injection provides the ability to inject artificial errors to |
| 8d438288 AM |
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 | |
| 4e79162a | 17 | injecting artificial errors to CPU notifier chain callbacks. |
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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. |