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cpu: rewrite cpu-notifier-error-inject module 

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>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Akinobu Mita 2012-07-30 14:43:03 -07:00 committed by Linus Torvalds
parent 8d43828814
commit f5a9f52e2c
2 changed files with 39 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
lib/Kconfig.debug
View File

@ -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.

63
lib/cpu-notifier-error-inject.c
View File

@ -1,58 +1,45 @@
#include <linux/kernel.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include "notifier-error-inject.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;
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;
return register_hotcpu_notifier(&err_inject_cpu_notifier);
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 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);