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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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