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    Subject[PATCH 12/12] add CPU notifier error injection module
    Date
    I used this module to test the series of modification to the
    cpu notifiers code.

    Example1: inject CPU offline error (-1 == -EPERM)

    # modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
    # echo 0 > /sys/devices/system/cpu/cpu1/online0
    bash: echo: write error: Operation not permitted

    Example2: inject CPU online error (-2 == -ENOENT)

    # modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
    # echo 1 > /sys/devices/system/cpu/cpu1/online0
    bash: echo: write error: No such file or directory

    Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
    ---
    lib/Kconfig.debug | 12 +++++++
    lib/Makefile | 1 +
    lib/cpu-notifier-error-inject.c | 63 +++++++++++++++++++++++++++++++++++++++
    3 files changed, 76 insertions(+), 0 deletions(-)
    create mode 100644 lib/cpu-notifier-error-inject.c

    diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
    index 8e5ec5e..ae467ed 100644
    --- a/lib/Kconfig.debug
    +++ b/lib/Kconfig.debug
    @@ -885,6 +885,18 @@ config LKDTM
    Documentation on how to use the module can be found in
    Documentation/fault-injection/provoke-crashes.txt

    +config CPU_NOTIFIER_ERROR_INJECT
    + tristate "CPU notifier error injection module"
    + depends on HOTPLUG_CPU && DEBUG_KERNEL
    + help
    + This option provides a kernel module that can be used to test
    + the error handling of the cpu notifiers
    +
    + To compile this code as a module, choose M here: the module will
    + be called cpu-notify-inject.
    +
    + If unsure, say N.
    +
    config FAULT_INJECTION
    bool "Fault-injection framework"
    depends on DEBUG_KERNEL
    diff --git a/lib/Makefile b/lib/Makefile
    index 2e152ae..9e34be2 100644
    --- a/lib/Makefile
    +++ b/lib/Makefile
    @@ -82,6 +82,7 @@ obj-$(CONFIG_AUDIT_GENERIC) += audit.o
    obj-$(CONFIG_SWIOTLB) += swiotlb.o
    obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
    obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
    +obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o

    lib-$(CONFIG_GENERIC_BUG) += bug.o

    diff --git a/lib/cpu-notifier-error-inject.c b/lib/cpu-notifier-error-inject.c
    new file mode 100644
    index 0000000..4dc2032
    --- /dev/null
    +++ b/lib/cpu-notifier-error-inject.c
    @@ -0,0 +1,63 @@
    +#include <linux/kernel.h>
    +#include <linux/cpu.h>
    +#include <linux/module.h>
    +#include <linux/notifier.h>
    +
    +static int priority;
    +static int cpu_up_prepare_error;
    +static int cpu_down_prepare_error;
    +
    +module_param(priority, int, 0);
    +MODULE_PARM_DESC(priority, "specify cpu notifier priority");
    +
    +module_param(cpu_up_prepare_error, int, 0644);
    +MODULE_PARM_DESC(cpu_up_prepare_error,
    + "specify error code to inject CPU_UP_PREPARE action");
    +
    +module_param(cpu_down_prepare_error, int, 0644);
    +MODULE_PARM_DESC(cpu_down_prepare_error,
    + "specify error code to inject CPU_DOWN_PREPARE action");
    +
    +static int err_inject_cpu_callback(struct notifier_block *nfb,
    + unsigned long action, void *hcpu)
    +{
    + int err = 0;
    +
    + switch (action) {
    + case CPU_UP_PREPARE:
    + case CPU_UP_PREPARE_FROZEN:
    + err = cpu_up_prepare_error;
    + break;
    + case CPU_DOWN_PREPARE:
    + case CPU_DOWN_PREPARE_FROZEN:
    + err = cpu_down_prepare_error;
    + break;
    + }
    + if (err)
    + printk(KERN_INFO "Injecting error (%d) at cpu notifier\n", err);
    +
    + return notifier_from_errno(err);
    +}
    +
    +static struct notifier_block err_inject_cpu_notifier = {
    + .notifier_call = err_inject_cpu_callback,
    +};
    +
    +static int err_inject_init(void)
    +{
    + err_inject_cpu_notifier.priority = priority;
    +
    + return register_hotcpu_notifier(&err_inject_cpu_notifier);
    +}
    +
    +static void err_inject_exit(void)
    +{
    + unregister_hotcpu_notifier(&err_inject_cpu_notifier);
    +}
    +
    +module_init(err_inject_init);
    +module_exit(err_inject_exit);
    +
    +MODULE_DESCRIPTION("CPU notifier error injection module");
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
    --
    1.6.0.6


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