Commit 8d438288 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds

fault-injection: notifier error injection

This patchset provides kernel modules that can be used to test the error
handling of notifier call chain failures by injecting artifical errors to
the following notifier chain callbacks.

 * CPU notifier
 * PM notifier
 * memory hotplug notifier
 * powerpc pSeries reconfig notifier

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

The patchset also adds cpu and memory hotplug tests to
tools/testing/selftests These tests first do simple online and offline
test and then do fault injection tests if notifier error injection
module is available.

This patch:

The notifier error injection provides the ability to inject artifical
errors to specified notifier chain callbacks.  It is useful to test the
error handling of notifier call chain failures.

This adds common basic functions to define which type of events can be
fail and to initialize the debugfs interface to control what error code
should be returned and which event should be failed.
Signed-off-by: default avatarAkinobu 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1d151c33
Notifier error injection
========================
Notifier error injection provides the ability to inject artifical errors to
specified notifier chain callbacks. It is useful to test the error handling of
notifier call chain failures which is rarely executed. There are kernel
modules that can be used to test the following notifiers.
* CPU notifier
* PM notifier
* Memory hotplug notifier
* powerpc pSeries reconfig notifier
CPU notifier error injection module
-----------------------------------
This feature can be used to test the error handling of the CPU notifiers by
injecting artifical errors to CPU notifier chain callbacks.
If the notifier call chain should be failed with some events notified, write
the error code to debugfs interface
/sys/kernel/debug/notifier-error-inject/cpu/actions/<notifier event>/error
Possible CPU notifier events to be failed are:
* CPU_UP_PREPARE
* CPU_UP_PREPARE_FROZEN
* CPU_DOWN_PREPARE
* CPU_DOWN_PREPARE_FROZEN
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)
# echo -2 > actions/CPU_UP_PREPARE/error
# echo 1 > /sys/devices/system/cpu/cpu1/online
bash: echo: write error: No such file or directory
PM notifier error injection module
----------------------------------
This feature is controlled through debugfs interface
/sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error
Possible PM notifier events to be failed are:
* PM_HIBERNATION_PREPARE
* PM_SUSPEND_PREPARE
* PM_RESTORE_PREPARE
Example: Inject PM suspend error (-12 = -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/pm/
# echo -12 > actions/PM_SUSPEND_PREPARE/error
# echo mem > /sys/power/state
bash: echo: write error: Cannot allocate memory
Memory hotplug notifier error injection module
----------------------------------------------
This feature is controlled through debugfs interface
/sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error
Possible memory notifier events to be failed are:
* MEM_GOING_ONLINE
* MEM_GOING_OFFLINE
Example: Inject memory hotplug offline error (-12 == -ENOMEM)
# cd /sys/kernel/debug/notifier-error-inject/memory
# echo -12 > actions/MEM_GOING_OFFLINE/error
# echo offline > /sys/devices/system/memory/memoryXXX/state
bash: echo: write error: Cannot allocate memory
powerpc pSeries reconfig notifier error injection module
--------------------------------------------------------
This feature is controlled through debugfs interface
/sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error
Possible pSeries reconfig notifier events to be failed are:
* PSERIES_RECONFIG_ADD
* PSERIES_RECONFIG_REMOVE
* PSERIES_DRCONF_MEM_ADD
* PSERIES_DRCONF_MEM_REMOVE
For more usage examples
-----------------------
There are tools/testing/selftests using the notifier error injection features
for CPU and memory notifiers.
* tools/testing/selftests/cpu-hotplug/on-off-test.sh
* tools/testing/selftests/memory-hotplug/on-off-test.sh
These scripts first do simple online and offline tests and then do fault
injection tests if notifier error injection module is available.
......@@ -1084,6 +1084,17 @@ config LKDTM
Documentation on how to use the module can be found in
Documentation/fault-injection/provoke-crashes.txt
config NOTIFIER_ERROR_INJECTION
tristate "Notifier error injection"
depends on DEBUG_KERNEL
select DEBUG_FS
help
This option provides the ability to inject artifical errors to
specified notifier chain callbacks. It is useful to test the error
handling of notifier call chain failures.
Say N if unsure.
config CPU_NOTIFIER_ERROR_INJECT
tristate "CPU notifier error injection module"
depends on HOTPLUG_CPU && DEBUG_KERNEL
......
......@@ -90,6 +90,7 @@ 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-$(CONFIG_NOTIFIER_ERROR_INJECTION) += notifier-error-inject.o
obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
lib-$(CONFIG_GENERIC_BUG) += bug.o
......
#include <linux/module.h>
#include "notifier-error-inject.h"
static int debugfs_errno_set(void *data, u64 val)
{
*(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);
return 0;
}
static int debugfs_errno_get(void *data, u64 *val)
{
*val = *(int *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
"%lld\n");
static struct dentry *debugfs_create_errno(const char *name, mode_t mode,
struct dentry *parent, int *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_errno);
}
static int notifier_err_inject_callback(struct notifier_block *nb,
unsigned long val, void *p)
{
int err = 0;
struct notifier_err_inject *err_inject =
container_of(nb, struct notifier_err_inject, nb);
struct notifier_err_inject_action *action;
for (action = err_inject->actions; action->name; action++) {
if (action->val == val) {
err = action->error;
break;
}
}
if (err)
pr_info("Injecting error (%d) to %s\n", err, action->name);
return notifier_from_errno(err);
}
struct dentry *notifier_err_inject_dir;
EXPORT_SYMBOL_GPL(notifier_err_inject_dir);
struct dentry *notifier_err_inject_init(const char *name, struct dentry *parent,
struct notifier_err_inject *err_inject, int priority)
{
struct notifier_err_inject_action *action;
mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
struct dentry *dir;
struct dentry *actions_dir;
err_inject->nb.notifier_call = notifier_err_inject_callback;
err_inject->nb.priority = priority;
dir = debugfs_create_dir(name, parent);
if (!dir)
return ERR_PTR(-ENOMEM);
actions_dir = debugfs_create_dir("actions", dir);
if (!actions_dir)
goto fail;
for (action = err_inject->actions; action->name; action++) {
struct dentry *action_dir;
action_dir = debugfs_create_dir(action->name, actions_dir);
if (!action_dir)
goto fail;
/*
* Create debugfs r/w file containing action->error. If
* notifier call chain is called with action->val, it will
* fail with the error code
*/
if (!debugfs_create_errno("error", mode, action_dir,
&action->error))
goto fail;
}
return dir;
fail:
debugfs_remove_recursive(dir);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(notifier_err_inject_init);
static int __init err_inject_init(void)
{
notifier_err_inject_dir =
debugfs_create_dir("notifier-error-inject", NULL);
if (!notifier_err_inject_dir)
return -ENOMEM;
return 0;
}
static void __exit err_inject_exit(void)
{
debugfs_remove_recursive(notifier_err_inject_dir);
}
module_init(err_inject_init);
module_exit(err_inject_exit);
MODULE_DESCRIPTION("Notifier error injection module");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
#include <linux/atomic.h>
#include <linux/debugfs.h>
#include <linux/notifier.h>
struct notifier_err_inject_action {
unsigned long val;
int error;
const char *name;
};
#define NOTIFIER_ERR_INJECT_ACTION(action) \
.name = #action, .val = (action),
struct notifier_err_inject {
struct notifier_block nb;
struct notifier_err_inject_action actions[];
/* The last slot must be terminated with zero sentinel */
};
extern struct dentry *notifier_err_inject_dir;
extern struct dentry *notifier_err_inject_init(const char *name,
struct dentry *parent, struct notifier_err_inject *err_inject,
int priority);
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