linux-kernel - [PATCH 2/2]suppress "Device nodeX does not have a release() function" warning

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Date:	Thu, 11 Oct 2012 14:26:46 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
CC:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	<rientjes@...gle.com>, <liuj97@...il.com>, <minchan.kim@...il.com>,
	<akpm@...ux-foundation.org>, <kosaki.motohiro@...fujitsu.com>,
	<wency@...fujitsu.com>
Subject: [PATCH 2/2]suppress "Device nodeX does not have a release() function"
 warning

When calling unregister_node(), the function shows following message at
device_release().

"Device 'node2' does not have a release() function, it is broken and must
be fixed."

The reason is node's device struct does not have a release() function.

So the patch registers node_device_release() to the device's release()
function for suppressing the warning message. Additionally, the patch adds
memset() to initialize a node struct into register_node(). Because the node
struct is part of node_devices[] array and it cannot be freed by
node_device_release(). So if system reuses the node struct, it has a garbage.

CC: David Rientjes <rientjes@...gle.com>
CC: Jiang Liu <liuj97@...il.com>
Cc: Minchan Kim <minchan.kim@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Signed-off-by: Wen Congyang <wency@...fujitsu.com>
---
 drivers/base/node.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

Index: linux-3.6/drivers/base/node.c
===================================================================
--- linux-3.6.orig/drivers/base/node.c	2012-10-11 10:04:02.149758748 +0900
+++ linux-3.6/drivers/base/node.c	2012-10-11 10:20:34.111806931 +0900
@@ -252,6 +252,14 @@ static inline void hugetlb_register_node
 static inline void hugetlb_unregister_node(struct node *node) {}
 #endif
 
+static void node_device_release(struct device *dev)
+{
+#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS)
+	struct node *node_dev = to_node(dev);
+
+	flush_work(&node_dev->node_work);
+#endif
+}
 
 /*
  * register_node - Setup a sysfs device for a node.
@@ -263,8 +271,11 @@ int register_node(struct node *node, int
 {
 	int error;
 
+	memset(node, 0, sizeof(*node));
+
 	node->dev.id = num;
 	node->dev.bus = &node_subsys;
+	node->dev.release = node_device_release;
 	error = device_register(&node->dev);
 
 	if (!error){

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