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Subject[PATCH -v5 2/6] cpu: rewrite cpu-notifier-error-inject module
Date
Rewrite existing cpu-notifier-error-inject module to use debugfs based
new framework.

This change removes cpu_up_prepare_error and cpu_down_prepare_error module
parameters which were used to specify error code to be injected. We could
keep these module parameters for backward compatibility by module_param_cb
but it seems overkill for this module.

This provides the ability to inject artifical errors to CPU notifier chain
callbacks. It is controlled through debugfs interface under
/sys/kernel/debug/notifier-error-inject/cpu

If the notifier call chain should be failed with some events
notified, write the error code to "actions/<notifier event>/error".

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

# cd /sys/kernel/debug/notifier-error-inject/cpu
# echo -1 > actions/CPU_DOWN_PREPARE/error
# echo 0 > /sys/devices/system/cpu/cpu1/online
bash: echo: write error: Operation not permitted
Example2: inject CPU online error (-2 == -ENOENT)

# cd /sys/kernel/debug/notifier-error-inject/cpu
# echo -2 > actions/CPU_UP_PREPARE/error
# echo 1 > /sys/devices/system/cpu/cpu1/online
bash: echo: write error: No such file or directory
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
No changes since v4
lib/Kconfig.debug | 16 ++++++++--
lib/cpu-notifier-error-inject.c | 63 ++++++++++++++++-----------------------
2 files changed, 39 insertions(+), 40 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c848758..be0c197 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1097,10 +1097,22 @@ config NOTIFIER_ERROR_INJECTION

config CPU_NOTIFIER_ERROR_INJECT
tristate "CPU notifier error injection module"
- depends on HOTPLUG_CPU && DEBUG_KERNEL
+ depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
help
This option provides a kernel module that can be used to test
- the error handling of the cpu notifiers
+ the error handling of the cpu notifiers by injecting artifical
+ errors to CPU notifier chain callbacks. It is controlled through
+ debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
+
+ If the notifier call chain should be failed with some events
+ notified, write the error code to "actions/<notifier event>/error".
+
+ Example: Inject CPU offline error (-1 == -EPERM)
+
+ # cd /sys/kernel/debug/notifier-error-inject/cpu
+ # echo -1 > actions/CPU_DOWN_PREPARE/error
+ # echo 0 > /sys/devices/system/cpu/cpu1/online
+ bash: echo: write error: Operation not permitted

To compile this code as a module, choose M here: the module will
be called cpu-notifier-error-inject.
diff --git a/lib/cpu-notifier-error-inject.c b/lib/cpu-notifier-error-inject.c
index 4dc2032..707ca24 100644
--- a/lib/cpu-notifier-error-inject.c
+++ b/lib/cpu-notifier-error-inject.c
@@ -1,58 +1,45 @@
#include <linux/kernel.h>
-#include <linux/cpu.h>
#include <linux/module.h>
-#include <linux/notifier.h>
+#include <linux/cpu.h>

-static int priority;
-static int cpu_up_prepare_error;
-static int cpu_down_prepare_error;
+#include "notifier-error-inject.h"

+static int priority;
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;
+static struct notifier_err_inject cpu_notifier_err_inject = {
+ .actions = {
+ { NOTIFIER_ERR_INJECT_ACTION(CPU_UP_PREPARE) },
+ { NOTIFIER_ERR_INJECT_ACTION(CPU_UP_PREPARE_FROZEN) },
+ { NOTIFIER_ERR_INJECT_ACTION(CPU_DOWN_PREPARE) },
+ { NOTIFIER_ERR_INJECT_ACTION(CPU_DOWN_PREPARE_FROZEN) },
+ {}
}
- 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 struct dentry *dir;
+
static int err_inject_init(void)
{
- err_inject_cpu_notifier.priority = priority;
+ int err;
+
+ dir = notifier_err_inject_init("cpu", notifier_err_inject_dir,
+ &cpu_notifier_err_inject, priority);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ err = register_hotcpu_notifier(&cpu_notifier_err_inject.nb);
+ if (err)
+ debugfs_remove_recursive(dir);

- return register_hotcpu_notifier(&err_inject_cpu_notifier);
+ return err;
}

static void err_inject_exit(void)
{
- unregister_hotcpu_notifier(&err_inject_cpu_notifier);
+ unregister_hotcpu_notifier(&cpu_notifier_err_inject.nb);
+ debugfs_remove_recursive(dir);
}

module_init(err_inject_init);
--
1.7.10.4


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