fault-injection: add CPU notifier error injection module

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From: Linux Kernel Mailing List
Date: Thursday, May 27, 2010 - 11:00 am

Gitweb:     http://git.kernel.org/linus/c9d221f86e43d9fb16260fe18a8cd6767f36c8a5
Commit:     c9d221f86e43d9fb16260fe18a8cd6767f36c8a5
Parent:     55af6bb509d3ef2696faddd4a734bf024794b337
Author:     Akinobu Mita <akinobu.mita@gmail.com>
AuthorDate: Wed May 26 14:43:36 2010 -0700
Committer:  Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Thu May 27 09:12:48 2010 -0700

    fault-injection: add CPU notifier error injection module
    
    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/online
    	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/online
    	bash: echo: write error: No such file or directory
    
    [akpm@linux-foundation.org: fix Kconfig help text]
    Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 lib/Kconfig.debug               |   12 +++++++
 lib/Makefile                    |    1 +
 lib/cpu-notifier-error-inject.c |   63 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 0 deletions(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2312089..e722e9d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -898,6 +898,18 @@ 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-notifier-error-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 9e6d3c2..c8567a5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -85,6 +85,7 @@ 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>");
--
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