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Subject[Patch v4 5/8] suppress "Device nodeX does not have a release() function" warning
Date
From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

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@google.com>
CC: Jiang Liu <liuj97@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
drivers/base/node.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 28216ce..4282e82 100644
--- 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;
}

--
1.8.0


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