PM: PM notifier error injection module

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

Each of the files in "error" directory represents an event which can be
failed and contains the error code.  If the notifier call chain should be
failed with some events notified, write the error code to the files.

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

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

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
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>

lib/Kconfig.debug

@@ -1119,6 +1119,30 @@ config CPU_NOTIFIER_ERROR_INJECT
 
 	  If unsure, say N.
 
+config PM_NOTIFIER_ERROR_INJECT
+	tristate "PM notifier error injection module"
+	depends on PM && NOTIFIER_ERROR_INJECTION
+	default m if PM_DEBUG
+	help
+	  This option provides the ability to inject artifical errors to
+	  PM notifier chain callbacks.  It is controlled through debugfs
+	  interface /sys/kernel/debug/notifier-error-inject/pm
+
+	  If the notifier call chain should be failed with some events
+	  notified, write the error code to "actions/<notifier event>/error".
+
+	  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
+
+	  To compile this code as a module, choose M here: the module will
+	  be called pm-notifier-error-inject.
+
+	  If unsure, say N.
+
 config FAULT_INJECTION
 	bool "Fault-injection framework"
 	depends on DEBUG_KERNEL

lib/Makefile

@@ -92,6 +92,7 @@ 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
+obj-$(CONFIG_PM_NOTIFIER_ERROR_INJECT) += pm-notifier-error-inject.o
 
 lib-$(CONFIG_GENERIC_BUG) += bug.o
 

lib/pm-notifier-error-inject.c

@@ -0,0 +1,49 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+
+#include "notifier-error-inject.h"
+
+static int priority;
+module_param(priority, int, 0);
+MODULE_PARM_DESC(priority, "specify PM notifier priority");
+
+static struct notifier_err_inject pm_notifier_err_inject = {
+	.actions = {
+		{ NOTIFIER_ERR_INJECT_ACTION(PM_HIBERNATION_PREPARE) },
+		{ NOTIFIER_ERR_INJECT_ACTION(PM_SUSPEND_PREPARE) },
+		{ NOTIFIER_ERR_INJECT_ACTION(PM_RESTORE_PREPARE) },
+		{}
+	}
+};
+
+static struct dentry *dir;
+
+static int err_inject_init(void)
+{
+	int err;
+
+	dir = notifier_err_inject_init("pm", notifier_err_inject_dir,
+					&pm_notifier_err_inject, priority);
+	if (IS_ERR(dir))
+		return PTR_ERR(dir);
+
+	err = register_pm_notifier(&pm_notifier_err_inject.nb);
+	if (err)
+		debugfs_remove_recursive(dir);
+
+	return err;
+}
+
+static void err_inject_exit(void)
+{
+	unregister_pm_notifier(&pm_notifier_err_inject.nb);
+	debugfs_remove_recursive(dir);
+}
+
+module_init(err_inject_init);
+module_exit(err_inject_exit);
+
+MODULE_DESCRIPTION("PM notifier error injection module");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");