[PATCH] kernel/reboot: add devm_register_reboot_notifier

[Andrey Smirnov <andrew.smirnov@gmail.com>]

Add devm_* wrapper around register_reboot_notifier to simplify device
specific reboot notifier registration/unregistration.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 include/linux/reboot.h |  3 +++
 kernel/reboot.c        | 27 +++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index a7ff409..0ca2541 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -38,6 +38,9 @@ extern int reboot_force;
 extern int register_reboot_notifier(struct notifier_block *);
 extern int unregister_reboot_notifier(struct notifier_block *);
 
+struct device;
+extern int devm_register_reboot_notifier(struct device *, struct notifier_block *);
+
 extern int register_restart_handler(struct notifier_block *);
 extern int unregister_restart_handler(struct notifier_block *);
 extern void do_kernel_restart(char *cmd);
diff --git a/kernel/reboot.c b/kernel/reboot.c
index bd30a97..e4ced88 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -104,6 +104,33 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
+static void devm_unregister_reboot_notifier(struct device *dev, void *res)
+{
+	WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
+}
+
+int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
+{
+	struct notifier_block **rcnb;
+	int ret;
+
+	rcnb = devres_alloc(devm_unregister_reboot_notifier,
+			    sizeof(*rcnb), GFP_KERNEL);
+	if (!rcnb)
+		return -ENOMEM;
+
+	ret = register_reboot_notifier(nb);
+	if (!ret) {
+		*rcnb = nb;
+		devres_add(dev, rcnb);
+	} else {
+		devres_free(rcnb);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(devm_register_reboot_notifier);
+
 /*
  *	Notifier list for kernel code which wants to be called
  *	to restart the system.
-- 
2.9.3