memory-hotplug: 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.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 28216ce74b3dadc4fa495d3f3e8ba335ddd30a0b..4282e82d9f26f38391bb30d7aa7cc6dd12dc9210 100644 (file)
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -252,6 +252,24 @@ static inline void hugetlb_register_node(struct node *node) {}
 static inline void hugetlb_unregister_node(struct node *node) {}
 #endif
 
+static void node_device_release(struct device *dev)
+{
+       struct node *node = to_node(dev);
+
+#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HUGETLBFS)
+       /*
+        * We schedule the work only when a memory section is
+        * onlined/offlined on this node. When we come here,
+        * all the memory on this node has been offlined,
+        * so we won't enqueue new work to this work.
+        *
+        * The work is using node->node_work, so we should
+        * flush work before freeing the memory.
+        */
+       flush_work(&node->node_work);
+#endif
+       kfree(node);
+}
 
 /*
  * register_node - Setup a sysfs device for a node.
@@ -265,6 +283,7 @@ int register_node(struct node *node, int num, struct node *parent)
 
        node->dev.id = num;
        node->dev.bus = &node_subsys;
+       node->dev.release = node_device_release;
        error = device_register(&node->dev);
 
        if (!error){
@@ -586,7 +605,6 @@ int register_one_node(int nid)
 void unregister_one_node(int nid)
 {
        unregister_node(node_devices[nid]);
-       kfree(node_devices[nid]);
        node_devices[nid] = NULL;
 }